230(3).

In FIG. 2E, logic circuit 232 includes inverters 234(7)-234(10), NOR gates 236(1)-236(2) and NAND gates 238(1)-238(2).

The input of inverter 234(7) receives timing signal POC0. The output of inverter 234(7) provides an inverted version of timing signal POC0 on a node 211(5), the inverted version of timing signal POC0 being referred to herein as the timing signal POC0_bar. The input of inverter 234(8) receives timing signal POC0_D1. The output of inverter 234(8) provides an inverted version of timing signal POC0_D1 on a node 211(6), the inverted version of timing signal POC0_D1 being referred to herein as timing signal POC0_D1_bar. The input of inverter 234(9) receives timing signal POC0_D2. The output of inverter 234(9) provides an inverted version of timing signal POC0_D2 on a node 211(7), the inverted version of timing signal POC0_D2 being referred to herein as timing signal POC0_D2_bar. The input of inverter 234(10) receives timing signal POC0_D3. The output of inverter 234(10) provides an inverted version of timing signal POC0_D3 on a node 211(8), the inverted version of timing signal POC0_D3 being referred to herein as timing signal POC0_D3_bar.

In FIG. 2E, NOR gate 236(1) receives the POC0_bar timing signal and timing signal POC0_D3_bar and generates gating signal POC1. NOR gate 236(2) receives timing signal POC0_D1_bar and timing signal POC0_D2_bar and generates gating signal POC2. NAND gate 238(1) receives timing signal POC0_D1_bar and timing signal POC0_D2_bar and generates gating signal POC3. NAND gate 238(2) receives the timing signal POC0_bar and timing signal POC0_D3_bar and generates gating signal POC4.

FIG. 2F is a graph of waveforms, in accordance with some embodiments.

More particularly, FIG. 2F is a graph of waveforms representing timing signal POC0, timing signal POC0_D1, timing signal POC0_D2, timing signal POC0_D3, gating signal POC1, gating signal POC2, gating signal POC3, and gating signal POC4, each of which has a logical high value (or ‘logical one’ value) at a time TO.

At a time T1, timing signal POC0 and gating signal POC1 transition to a logical low value (or ‘logical zero’ value), with a result that gating signal POC1 enables output level shifter 218 of FIG. 2A.

At a time T2, which is after the output of output level shifter 218 has stabilized, timing signal POC0_D1 and gating signal POC2 transition to a logical low value, with a result that gating signal POC2 enables output driver 220 of FIG. 2A.

At a time T3, timing signal POC0_D2 and gating signal POC3 transition to a logical low value, with a result that gating signal POC3 enables input buffer 222 of FIG. 2A. In some embodiments, the time T3 is after the PAD signal on terminal 214 has stabilized.

At a time T4, which is after the output of input buffer 222 has stabilized, timing signal POC0_D3 and gating signal POC4 transition to a logical low value, with a result that gating signal POC4 enables input level shifter 224 of FIG. 2A.

At a time T5, timing signal POC0 and gating signal POC4 transition to a logical high value (or ‘logical one’ value), with a result that gating signal POC4 disables input level shifter 224. At a time T6, timing signal POC0_D1 and gating signal POC3 transition to a logical high value, with a result that gating signal POC3 disables input buffer 222. At a time T7, timing signal POC0_D2 and gating signal POC2 transition to a logical high value, with a result that gating signal POC2 disables output driver 220. At a time T8, timing signal POC0_D3 and gating signal POC1 transition to a logical high value, with a result that gating signal POC1 disables output level shifter 218.

In FIG. 2F, according to some embodiments, the cascaded transitions of gating signals POC1, POC2, POC3 and POC4 at corresponding times T1, T2, T3 and T4 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are ready for I/O exchange with I/O system 204. Also in FIG. 2F, according to some embodiments, the cascaded transitions of gating signals POC4, POC3, POC2 and POC1 at corresponding times T5, T6, T7 and T8 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are not ready for I/O exchange with I/O system 204.

In at least some embodiments, I/O system 204 avoids the first glitching issue suffered by the other approach because gating signals generator 206 is configured to enable output level shifter 218 with gating signal POC1, wait for an output signal of output level shifter 218 to stabilize, and then enable output driver 220 with gating signal POC2. In at least some embodiments, I/O system 204 avoids the second glitching issue suffered by the other approach because gating signals generator 206 is configured to enable input buffer 222 with gating signal POC3, wait for the output signal of input buffer 222 to stabilize, and then enable input level shifter 224 with gating signal POC4.

FIG. 2G is a schematic diagram of a power-on (PO) signal generator 210′, in accordance with some embodiments. FIG. 2H is a schematic diagram showing PO signal generator 210′ in more detail, in accordance with some embodiments. FIGS. 2I-2K are graphs of corresponding waveforms, in accordance with some embodiments.

PO signal generator 210′ is similar to PO signal generator 210. For brevity, the discussion will focus more on differences between FIGS. 2G-2K and FIGS. 2B-2D than on similarities.

PO signal generator 210′ is configured to monitor a state of a voltage VDD1 (monitored voltage VDD1) and correspondingly generate timing signal POC0′. As compared to PO signal generator 210 of FIG. 2B, PO signal generator 210′ of FIG. 2G includes a supply-variation sensitivity-reducing (SVSR) load 227(1) coupled between first reference voltage VDD2 and node 225(1). Also in FIG. 2G, the output of buffer 226 provides the timing signal POC0′ rather than the timing signal POC0 as in FIG. 2B. The voltage on the gate electrode of NMOS transistor N1, namely, reference voltage VDD1, is fed back as an input to SVSR load 227(1).

In FIG. 2H, SVSR load 227(1) is shown in more detail. SVSR load 227(1) includes a resistor R0′ coupled between first reference voltage VDD2 and a node 225(2); and a PMOS transistor P1 coupled between node 225(2) and node 225(1). The gate electrode of PMOS transistor P1 is configured to receive reference voltage VDD1.

Again, FIG. 2I is a graph of waveforms in accordance with some embodiments. More particularly, FIG. 2I is a graph of waveforms related to the operation of PO signal generator 210′ of FIGS. 2G-2H. In FIG. 2I, it is assumed that VDD2 is substantially constant.

FIG. 2I includes: a waveform 229(1) representing VDD1; a waveform 229(2) representing a threshold voltage of PO signal generator 210′, Vt_210′; a waveform 229(3) representing Vcs on node 225(1); a waveform 229(4) representing a voltage, V_225(2), on node 225(2); a waveform 229(5) representing a source-to-gate voltage of PMOS transistor P1, Vsg_P1; and a waveform 229(6) representing timing signal POC0′.

In FIG. 2I, when VDD1 waveform 229(1) is well below the threshold of NMOS transistor N1 Vt_N1, NMOS transistor N1 is turned off, each of Vcs waveform 229(3), V_225(2) waveform 229(4) and Vsg_P1 waveform 229(5) is pulled to a logical high value and timing signal POC0′ waveform 229(6) is pulled to a logical high value. The transition from a logical high value to a logical low value at time t1 is sharp for timing signal POC0′ waveform 229(6), and, as compared to timing signal POC0′ waveform 229(6), progressively more gradual for Vcs waveform 229(3), V_225(2) waveform 229(4) and Vsg_P1 waveform 229(5). In some embodiments, a sharp transition of a signal is a step-like transition. In some embodiments, a sharp transition of a signal is similar to transitions in a square wave. In some embodiments in which a transition of a first signal is described as sharp and corresponding transitions of second and third signals are described as progressively more gradual, the transition of the second signal is curvilinear as compared to the sharp transition of the first signal, and the transition of the third signal is more curvilinear as compared to the transition of the second signal. In some embodiments in which a transition of a first signal is described as sharp and corresponding transitions of second and third signals are described as progressively more gradual, the transition of the second signal is rounded as compared to the sharp transition of the first signal, and the transition of the third signal is more rounded as compared to the transition of the second signal.

When VDD1 waveform 229(1) reaches and rises above Vt_N1 at time t1, NMOS transistor N1 turns on, and each of Vcs waveform 229(3), V225(2) waveform 229(4) and Vsg_P1 waveform 229(5) is pulled down to a logical low value and timing signal POC0′ is pulled down to a logical low value.

VDD1 waveform 229(1) peaks at time t2. Between time t1 and time t2, V_225(2) waveform 229(4) substantially follows VDD1 waveform 229(1).

In FIG. 2I, when VDD1 waveform 229(1) falls below Vt_N1 at time t3, NMOS transistor N1 is turned off, each of Vcs waveform 229(3), V225(2) waveform 229(4) and Vsg_P1 waveform 229(5) is pulled up to a logical high value, and timing signal POC0′ is pulled up to a logical high value. The transition from a logical low value to a logical high value at time t3 is sharp for timing signal POC0′ waveform 229(6), and, as compared to timing signal POC0′ waveform 229(6), progressively more gradual for Vcs waveform 229(3), V_225(2) waveform 229(4) and Vsg_P1 waveform 229(5).

In some embodiments in which it is assumed that VDD2 is substantially constant, Vt_210′ is about 0.349 volts. In some embodiments in which it is assumed that VDD2 is substantially constant, the following is true: a logical low value is VSS, e.g., zero volts; a logical high value of Vcs waveform 229(3), V_225(2) waveform 229(4), Vsg_P1 waveform 229(5), and timing signal POC0′ is about 1.2 volts; and a peak value of VDD1 waveform 229(1) is about 0.75 volts. In some embodiments in which VDD2 exhibits variation, a maximum value of VDD2 is about 1.2 volts.

Another approach (AA) for configuring a PO signal generator (POSG) (not shown) is similar to PO signal generator 210′ of FIG. 2B except that resistor R0 of FIG. 2B is replaced by a weak PMOS transistor, P_weak (not shown), in order to reduce leakage current through NMOS transistor N1. Typically, P_weak is implemented as a long channel PMOS transistor or a stack of PMOS transistors, either of which implementations have a corresponding disadvantage of occupying a large area. Despite reducing the leakage current overall, however, the POSG according to the other approach is more susceptible to variations in VDD2, which negatively affects leakage current, and furthermore worsens variations in the threshold voltage of the POSG, Vt_POSG_AA (not shown) as compared to Vt_210 of FIG. 2C.

Again, FIG. 2J is a graph of waveforms in accordance with some embodiments. More particularly, FIG. 2J is a graph of waveforms representing threshold voltages of PO signal generators.

FIG. 2J includes a waveform 229(7) representing Vt_210′ and a waveform 229(8) representing Vt_POSG_AA. In FIG. 2J, where VDD2 is the abscissa (X-axis) and threshold voltage for a corresponding PO signal generator is the ordinate (Y-axis).

The slope of Vt_210′ waveform 229(7) is smaller than the slope of Vt_POSG_AA waveform 229(8). SVSR load 227(1) helps reduce the slope of Vt_210′ waveform 229(7) by reducing the effects of variations in VDD2 upon the operation of PO signal generator 210′. When VDD2 varies from a low value to a high value, Vsg_P1 is larger, which strengthens the current conducting capability of PMOS transistor P1 and results in a greater/higher value of Vt_210′.

A benefit of SVSR load 227(1)/227(2), and therefore of PO signal generator 210′, is that Vt_210′ waveform 229(2) is less sensitive to variation in VDD2 than is Vt_POSG_AA waveform 229(8) of POSG according to the other approach. Another benefit of SVSR load 227(1), and therefore of PO signal generator 210′, is that PMOS transistor P1 is moderately sized, and so PO signal generator 210′ is smaller than the POSG according to the other approach.

Again, FIG. 2K is a graph of waveforms in accordance with some embodiments. More particularly, FIG. 2K is a graph of waveforms representing threshold voltages of PO signal generators. In FIG. 2K, where VDD2 is the abscissa (X-axis) and threshold voltage for a corresponding PO signal generator is the ordinate (Y-axis).

FIG. 2K includes a waveform 229(9) representing current through NMOS transistor N1 of PO signal generator 210′ of FIGS. 2G-2H; a waveform 229(10) representing current through NMOS transistor N1 of PO signal generator 210 of FIG. 2B; and a waveform 229(11) representing current through NMOS transistor N1 (not shown) of the POSG (not shown) according to the other approach.

In FIG. 2K, NMOS transistor N1 is off before time t1, is on during the interval t1 to t3, and is off after time t3. In general, a large current is beneficial when NMOS transistor N1 is ON. Also, in general, a small current (leakage) is beneficial when NMOS transistor N1 is off, e.g., to reduce standby power consumption. As compared to waveforms 229(10) and 229(11), waveform 229(10) strikes a better balance between having a relatively large current when NMOS transistor N1 is ON, and a relatively small current (leakage) when NMOS transistor N1 is off.

FIG. 2L is a schematic diagram of a power-on (PO) signal generator 210″, in accordance with some embodiments. FIG. 2L shows a different embodiment of PO signal generator 210′ of FIG. 2G, as compared to FIG. 2H. FIGS. 2M-2N are graphs of corresponding waveforms, in accordance with some embodiments.

In FIG. 2L, PO signal generator 210″ is similar to PO signal generator 210′ of FIG. 2H. For brevity, the discussion will focus more on differences between FIGS. 2L-2M and FIGS. 2G-2K than on similarities.

PO signal generator 210″ is configured to monitor a state of a voltage VDD1 (monitored voltage VDD1) and correspondingly generate timing signal POC0″. As compared to supply-variation sensitivity-reducing (SVSR) load 227(2) of FIG. 2H, SVSR load 227(3) of FIG. 2L includes: a resistor R1′ and a PMOS transistor P2 coupled in parallel between first reference voltage VDD2 and a node 225(3); an inverter 231(1) coupled between node 225(1) and a node 225(4); and an inverter 231(2) whose input is coupled to node 225(4) and whose output provides the timing signal POC0″. PMOS transistor P2 serves as a switch to selectively bypass resistor R1′.

In FIG. 2L, resistor R0″ is coupled between node 225(3) and node 225(2), whereas corresponding resistor R0′ in FIG. 2H is coupled between VDD2 and node 225(2). In FIG. 2L, inverters 231(1) and 231(2) are shown as being included in buffer 226′. In FIG. 2L, a voltage ‘Vcs bar’ (Vcsb) is on node 225(4). In FIG. 2L, the gate electrode of PMOS transistor P2 is configured to receive voltage Vcsb.

Again, FIG. 2M is a graph of waveforms in accordance with some embodiments. More particularly, FIG. 2M is a graph of waveforms related to the operation of PO signal generator 210″ of FIG. 2L. In FIG. 2M, it is assumed that VDD2 is substantially constant.

FIG. 2M includes: a waveform 229(1)′ representing VDD1; a waveform 229(3)′ representing Vcs on node 225(1); a waveform 229(12) representing Vcsb on node 225(4); a waveform 229(13) representing a voltage, V_225(3), on node 225(3); a waveform 229(4)′ representing a voltage, V_225(2), on node 225(2); a waveform 229(5)′ representing Vsg of PMOS transistor P1, Vsg_P1; and a waveform 229(6)′ representing timing signal POC0″.

In FIG. 2M, when VDD1 waveform 229(1)′ is well below the threshold of NMOS transistor N1, Vt_N1, NMOS transistor N1 is turned off, each of Vcs waveform 229(3)′, V_225(3) waveform 229(13); V_225(2) waveform 229(4)′ and Vsg_P1 waveform 229(5)′ is pulled to a logical high value, Vcsb waveform 229(12) is pulled down to a logical low value, and timing signal POC0″ is pulled to a logical high value. As such, when VDD1 waveform 229(1)′ is well below Vt_N1, the logical low value of Vcsb waveform 229(12) turns on PMOS transistor P2, which places resistor R1′ in parallel with a substantially lower resistance (namely, P2). When PMOS transistor P2 is turned ON, resistor R1′ is effectively bypassed as most of the current between VDD2 and node 225(3) is shunted through PMOS transistor P1, with a result that the resistance between VDD2 and node 225(2) is substantially R0″. Before time t1, when the resistance between VDD2 and node 225(2) is substantially R0″, Vt_210″ is greater than Vt_N1, such that Vt_N1<Vt_210″.

When VDD1 waveform 229(1)′ reaches and rises above Vt_N1 at time t1, NMOS transistor N1 is turning, and each of Vcs waveform 229(3)′, V_225(3) waveform 229(13), V225(2) waveform 229(4)′ and Vsg_P1 waveform 229(5)′ is pulled down to a logical low value, Vcsb waveform 229(12) is pulled up to a logical high value, and timing signal POC0″ is pulled down to a logical low value. The transition from a logical high value to a logical low value at time t1 is sharp for timing signal POC0″ waveform 229(6)′, is substantially sharp for Vcsb waveform 229(12), and, as compared to Vcsb waveform 229(12), progressively more gradual for Vcs waveform 229(3)′, V_225(2) waveform 229(4)′ and Vsg_P1 waveform 229(5)′. The transition from a logical low value to a logical high value at time t1 of V_225(3) waveform 229(13) is substantially sharp. As such, when VDD1 waveform 229(1)′ rises above Vt_N1 at time t1, the logical high value of Vcsb waveform 229(12) turns off PMOS transistor P2, which places resistor R1′ in parallel with a substantially higher resistance (namely, P2). When PMOS transistor P2 is turned OF, most of the current between VDD2 and node 225(3) is shunted through resistor R1′, with a result that the resistance between VDD2 and node 225(2) is substantially increased to R1′+R0″. From time t1 to t3, when the resistance between VDD2 and node 225(2) is substantially R1′+R0″, Vt_210″ is substantially equal to Vt_N1, such that Vt_210″ ˜ Vt_N1.

VDD1 waveform 229(1)′ peaks at time t2. Between time t2 and time t3, each of V_225(3) waveform 229(13) and V_225(2) waveform 229(4)′ substantially follows VDD1 waveform 229(1)′.

When VDD1 waveform 229(1)′ falls below Vt_N1 at time t3, NMOS transistor N1 is turned off, each of Vcs waveform 229(3)′, V_225(3) waveform 229(13), V225(2) waveform 229(4)′ and Vsg_P1 waveform 229(5)′ is pulled up to a logical high value, Vcsb waveform 229(12) is pulled down to a logical low value, and timing signal POC0″ is pulled up to a logical high value. The transition from a logical low value to a logical high value at time t3 is sharp for timing signal POC0″ waveform 229(6)′, is substantially sharp for Vcsb waveform 229(12), and, as compared to Vcsb waveform 229(12), progressively more gradual for Vcs waveform 229(3)′, V_225(2) waveform 229(4)′ and Vsg_P1 waveform 229(5)′. The transition from a logical high value to a logical low value at time t3 of V_225(3) waveform 229(13) is substantially sharp. After time t3, when the resistance between VDD2 and node 225(2) is substantially R0″, Vt_210″ is greater than Vt_N1, such that Vt_N1<Vt_210″.

The differing values of Vt_210″ over time, namely Vt_210″, Vt_210″, and Vt_210″, represent hysteresis in Vt_210″, as shown in FIG. 2N.

Again, FIG. 2N is a graph of waveforms in accordance with some embodiments. More particularly, FIG. 2N is a graph of waveforms related to the operation of PO signal generator 210″ of FIG. 2K. In FIG. 2N, it is assumed that VDD2 is substantially constant.

FIG. 2N includes: a waveform 229(1)′ representing VDD1; a waveform 229(12) representing Vcsb on node 225(4); a waveform 229(2)′ representing Vt_210″.

In FIG. 2N, Vt_210″ waveform 229(2)′ shows hysteresis. In particular, the values Vt_210″ and Vt_210″ are substantially the same and will be referred to as Vt_210″. However, Vt_210″ is less than Vt_210″, which represents hysteresis.

In some embodiments in which it is assumed that VDD2 is substantially constant, Vt_210″ is about 0.349 volts, and Vt_210″ is about 0.383 volts.

A benefit of SVSR load 227(3), and therefore of PO signal generator 210″, is that Vt_210″ waveform 229(2)′ is less sensitive to variation in VDD2 than Vt_210′ of FIGS. 2G-2H, and therefore even less sensitive to variation in VDD2 than is Vt_POSG_AA of the other approach.

FIG. 3A is a schematic diagram of an I/O system 304, in accordance with some embodiments. FIG. 3B is a schematic diagram showing gating signals generator 306 in more detail, in accordance with some embodiments. FIG. 3C is a graph of waveforms, in accordance with some embodiments.

I/O system 304 of FIG. 3A reflect a scenario in which a glitch on output path and a glitch on the input path are prevented. In some embodiments, as compared with I/O system 204 of FIG. 2A, I/O system 304 of FIG. 3A is less complex. In some embodiments, as compared with I/O system 204 of FIG. 2A, I/O system 304 of FIG. 3A consumes a smaller area (has a smaller footprint).

FIGS. 3A-3C follow a numbering convention similar to that of FIGS. 2A-2F, albeit with FIGS. 3A-3C using 3-series numbering to introduce new elements whereas FIGS. 2A-2F use 2-series numbering. Elements in FIGS. 3A-3C carried over from FIGS. 2A-2F continue to use the 2-series numbing of FIGS. 2A-2F. For brevity, the discussion will focus more on differences between FIGS. 3A-3C and FIGS. 2A-2F than on similarities.

I/O system 304 includes: PO signal generator 210; a gating signals generator 306; and a multi-gated I/O interface 308. Gating signals generator 306 differs from gating signals generator 206 in that gating signals generator 306 generates gating signals POC1′, POC2′ and POC3′ but not gating signal POC4.

Accordingly, multi-gated I/O interface 308 is configured to receive gating signals POC1′, POC2′ and POC3′ but not gating signal POC4. Multi-gated I/O interface 308 includes: an output level shifter 318 coupled between output terminal 212 and a node 319; an output driver 320 coupled between node 319 and external terminal 214; an input buffer 322 coupled between external terminal 214 and a node 323; and an input level shifter 324 coupled between node 323 and input node of 216.

More particularly, multi-gated I/O interface 308 is configured to receive gating signals POC1′, POC2′ and POC3′ (but not gating signal POC4) as follows: output level shifter 318 is configured to receive gating signal POC1′ as an enablement signal; output driver 320 and input buffer 322 are configured correspondingly to receive gating signal POC2′ as an enablement signal; and input level shifter 324 is configured to receive gating signal POC3′ as an enablement signal. See, e.g., FIG. 3C for the relative timing of gating signals POC1′, POC2′ and POC3′.

FIG. 3B is a schematic diagram showing gating signals generator 306 in more detail, in accordance with some embodiments.

Gating signals generator 306 includes a delay chain 328 and a logic circuit 332. Delay chain 328 differs from delay chain 228 in that delay chain 328 includes delay cell 230(1) and 230(2) but not delay cell 230(3).

Logic circuit 332 differs from logic circuit 232 in several ways. The differences include the following. Logic circuit 332 includes: inverters 234(7)-234(9) but not inverter 234(10); NOR gate 336(3) but not NOR gates 236(1) and 236(2); an inverter 334(11) instead of NAND gate 238(1); and NAND gate 338(3) instead of NAND gate 238(2). Also, logic circuit 332 does not include NAND gate 238(2). Inverter 234(7) provides POC0_bar timing signal on a node 311(9) in FIG. 3B. Inverter 234(8) provides POC0_D1_bar timing signal on a node 311(10) in FIG. 3B; and inverter 234(9) provides POC0_D2_bar timing signal on a node 311(11) in FIG. 3B.

In FIG. 3B, NOR gate 336(3) receives timing signal POC0_bar and timing signal POC0_D2_bar and generates gating signal POC1′. As NOR gate 336(3) receives different inputs than corresponding NOR gate 236(1), the output of NOR gate 336(3) is referred to as gating signal POC1′ rather than gating signal POC1. Inverter 334(11) receives timing signal POC0_D1_bar and generates gating signal POC2′. As inverter 334(11) of FIG. 3B replaces corresponding NOR gate 236(2) of FIG. 2E, the output of inverter 334(11) is referred to as gating signal POC2′ rather than gating signal POC2. NAND gate 338(3) receives timing signal POC0_bar and timing signal POC0_D2_bar and generates gating signal POC3′. As NAND gate 338(3) receives different inputs than corresponding NAND gate 238(1), the output of NAND gate 338(3) is referred to as gating signal POC3′ rather than gating signal POC3.

FIG. 3C is a graph of waveforms, in accordance with some embodiments.

More particularly, FIG. 3C is a graph of waveforms representing timing signal POC0, timing signal POC0_D1 and timing signal POC0_D2 but not timing signal POC0_D3, as well as gating signal POC1′, gating signal POC2′ and gating signal POC3 but not gating signal POC4, each of which has a logical high value (or ‘logical one’ value) at a time T0.

At a time T1, timing signal POC0 and gating signal POC1′ transition to a logical low value (or ‘logical zero’ value), with a result that gating signal POC1′ enables output level shifter 318 of FIG. 3A.

At a time T2, which is after the output of output level shifter 318 has stabilized, timing signal POC0_D1 and gating signal POC2′ transition to a logical low value, with a result that gating signal POC2′ enables output driver 320 and input buffer 322 of FIG. 3A.

At a time T3, timing signal POC0_D2 and gating signal POC3′ transition to a logical low value, with a result that gating signal POC3′ enables input level shifter 324 of FIG. 3A. In some embodiments, the time T3 is after the PAD signal on terminal 214 has stabilized. In some embodiments, the time T3 is after the output of input buffer 322 has stabilized.

At a time T6, timing signal POC0 and gating signal POC3′ transition to a logical high value (or ‘logical high’ value), with a result that gating signal POC3′ disables input level shifter 324. At a time T7, timing signal POC0_D1 and gating signal POC2′ transition to a logical high value, with a result that gating signal POC2′ disables output driver 320 and input buffer 322. At a time T8, timing signal POC0_D2 and gating signal POC1′ transition to a logical high value, with a result that gating signal POC1′ disables output level shifter 318.

In at least some embodiments, I/O system 304 avoids the first glitching issue suffered by the other approach because gating signals generator 306 is configured to enable output level shifter 318 with gating signal POC1′, wait for an output signal of output level shifter 318 to stabilize, and then enable output driver 320 with gating signal POC2′. In at least some embodiments, I/O system 304 avoids the second glitching issue suffered by the other approach because gating signals generator 306 is configured to enable input buffer 322 with gating signal POC2′, wait for the output signal of input buffer 322 to stabilize, and then enable input level shifter 324 with gating signal POC3′.

In FIG. 3C, according to some embodiments, the cascaded transitions of gating signals POC1′, POC2′ and POC3′ at corresponding times T1, T2 and T3 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are ready for I/O exchange with I/O system 304. Also in FIG. 3C, according to some embodiments, the cascaded transitions of gating signals POC3′, POC2′ and POC1′ at corresponding times T6, T7 and T8 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are not ready for I/O exchange with I/O system 304.

FIG. 4A is a schematic diagram of an I/O system 404, in accordance with some embodiments. FIG. 4B is a schematic diagram showing gating signals generator 406 in more detail, in accordance with some embodiments. FIG. 4C is a graph of waveforms, in accordance with some embodiments. FIG. 4D is a graph of waveforms, in accordance with some embodiments.

I/O system 404 of FIG. 4A reflects a scenario in which prevention of a glitch on the output path is the focus rather than prevention of glitches on both the input path and the output path. In some embodiments, as compared to I/O system 204 of FIG. 2A or I/O system 304 of FIG. 3A, I/O system 404 of FIG. 4A is less complex. In some embodiments, as compared to I/O system 204 of FIG. 2A or I/O system 304 of FIG. 3A, I/O system 404 of FIG. 4A consumes a smaller area (has a smaller footprint).

FIGS. 4A-4D follow a numbering convention similar to that of FIGS. 3A-3C, albeit with FIGS. 4A-4D using 4-series numbering to introduce new elements whereas FIGS. 3A-3C use 3-series numbering. Elements in FIGS. 4A-4D carried over from FIGS. 2A-2F continue to use the 2-series numbing of FIGS. 2A-2F. Elements in FIGS. 4A-4D carried over from FIGS. 3A-3C continue to use the 3-series numbing of FIGS. 3A-3C. For brevity, the discussion will focus more on differences between FIGS. 4A-4D and FIGS. 3A-3C than on similarities.

I/O system 404 includes: PO signal generator 210; a gating signals generator 406; and a multi-gated I/O interface 408. Gating signals generator 406 differs from gating signals generator 306 in that gating signals generator 306 generates gating signals POC1′ and POC2′ but not gating signal POC3′.

Accordingly, multi-gated I/O interface 408 is configured to receive to gating signals POC1′ and POC2′ but not gating signal POC3′. Multi-gated I/O interface 408 includes: an output level shifter 418 coupled between output terminal 212 and a node 419; an output driver 420 coupled between node 419 and external terminal 214; an input buffer 422 coupled between external terminal 214 and a node 423; and an input level shifter 424 coupled between node 423 and input node of 216.

More particularly, multi-gated I/O interface 408 is configured to receive gating signals POC1′ and POC2′ (but not gating signal POC3′) as follows: output level shifter 418, input buffer 422, and input level shifter 424 are configured to receive gating signal POC1′ as an enablement signal; and output driver 420 is configured to receive gating signal POC2′ as an enablement signal. Sec, e.g., FIGS. 4C-4D for the relative timing of gating signals POC1′ and POC2′.

FIG. 4B is a schematic diagram showing gating signals generator 406 in more detail, in accordance with some embodiments.

Gating signals generator 406 includes delay chain 328 and a logic circuit 432. Logic circuit 432 differs from logic circuit 332 does not include NAND gate 338(3).

FIG. 4C is a graph of waveforms, in accordance with some embodiments.

More particularly, FIG. 4C is a graph of waveforms representing gating signal POC1′ and gating signal POC2′, but not timing signal POC0, nor timing signal POC0_D1, nor timing signal POC0_D2, nor gating signal POC3′. Each of gating signal POC1′ and gating signal POC2′ has a logical high value (or ‘logical one’ value) at a time TO.

At a time T1, gating signal POC1′ transitions to a logical low value (or ‘logical zero’ value), with a result that gating signal POC1′ enables output level shifter 418, input buffer 422 and input level shifter 424 of FIG. 4A.

At a time T2, which is after the output of output level shifter 418 has stabilized, gating signal POC2′ transitions to a logical low value, with a result that gating signal POC2′ enables output driver 420 of FIG. 4A.

At a time T7, gating signal POC2′ transitions to a logical high value (or ‘logical one’ value), with a result that gating signal POC2′ disables output driver 420. At a time T8, gating signal POC1′ transitions to a logical high value, with a result that gating signal POC1′ disables output level shifter 418, input buffer 422 and input level shifter 424.

FIG. 4D is a graph of waveforms, in accordance with some embodiments.

More particularly, FIG. 4D shows waveforms representing PAD signal 442 on external terminal 214 of FIG. 4A, an output core data signal 443 on output terminal 212 of FIG. 4A, an enable signal 444 for output driver 420 of FIG. 4A, gating signal POC1′ waveform 445 and gating signal POC2′ waveform 446. In some embodiments, enable signal 444 is based on gating signal POC2′ waveform 446. In some embodiments, enable signal 444 is generated by one or more components (not shown) which are included in output driver 420.

Each of PAD signal 442, gating signal POC1′ waveform 445 and gating signal POC2′ waveform 446 has a logical high value (or ‘logical one’ value) at a time T40. Each of output core data signal 443 and enable signal 444 for output driver 420 of FIG. 4A has a logical low value (or ‘logical zero’ value) at a time T40. At a time T41, gating signal POC1′ waveform 445 transitions to a logical low value, with a result that gating signal POC1′ waveform 445 enables output level shifter 418, and also enables input buffer 422 and input level shifter 424.

Also at time T41: output core data signal 443 begins a slow transition 447 from the logical low value to the logical high value, reaching the logical high value at time T42; and gating signal POC2′ waveform 446 remains at the logical high value, which prevents PAD signal 442 from otherwise experiencing a glitch 448. As glitch 448 does not actually occur, glitch 448 is shown with phantom (dashed) lines. Glitch 448 is represented by PAD signal 442 otherwise transitioning to the logical low value at time T41 and then returning to the logical high value at time T42.

More particularly, at time T41, by remaining at the logical high value, gating signal POC2′ waveform 446 continues to disable output driver 420 and thereby prevents enable signal 444 for output driver 420 from following slow transition 447 from the logical low value to the logical high value of output core data signal 443 during T41-T42. If output driver 420 otherwise was enabled at time T41 so that enable signal 444 for output driver 420 instead followed slow transition 447 (again, from the logical low value to the logical high value of output core data signal 443 during T41-T42), then PAD signal 442 otherwise would experience glitch 448.

At a time T43, which is after output core data 443 has stabilized and thus after the output signal (not shown) of output level shifter 418 has stabilized, gating signal POC2′ waveform 446 transitions to a logical low value, with a result that gating signal POC2′ waveform 446 enables output driver 420. As such and in at least some embodiments, I/O system 404 avoids the first glitching issue suffered by the other approach because gating signals generator 406 is configured to enable output level shifter 418 with gating signal POC1′ waveform 445, wait for the output signal (not shown) of output level shifter 418 to stabilize, and then enable output driver 420 with gating signal POC2′ waveform 446.

In FIG. 4C, according to some embodiments, the cascaded transitions of gating signals POC1′ and POC2′ at corresponding times T1 and T2 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are ready for I/O exchange with I/O system 404. Also in FIG. 4C, according to some embodiments, the cascaded transitions of gating signals POC2 and POC1 at corresponding times T7 and T8 assume a circumstance in which components (not shown) in the core (not shown, but see core region 102 FIG. 1) are not ready for I/O exchange with I/O system 404.

FIG. 5A is a schematic diagram of an I/O system 504, in accordance with some embodiments. FIG. 5B is a graph of waveforms, in accordance with some embodiments.

The embodiments of FIGS. 5A-5B reflect a scenario in which prevention of a glitch on the input path is the focus rather than prevention of glitches on both the input path and the output path. In some embodiments, as compared to I/O system 204 of FIG. 2A or I/O system 304 of FIG. 3A, I/O system 504 of FIG. 5A is less complex. In some embodiments, as compared to I/O system 204 of FIG. 2A or I/O system 304 of FIG. 3A, I/O system 504 of FIG. 5A consumes a smaller area (has a smaller footprint).

FIGS. 5A-5B follow a numbering convention similar to that of FIGS. 4A-4D, albeit with FIGS. 5A-5B using 5-series numbering to introduce new elements whereas FIGS. 4A-4C use 4-series numbering. Elements in FIGS. 5A-5B carried over from FIGS. 2A-2F continue to use the 2-series numbing of FIGS. 2A-2F. Elements in FIGS. 5A-5B carried over from FIGS. 4A-4D continue to use the 4-series numbing of FIGS. 4A-4D. For brevity, the discussion will focus more on differences between FIGS. 5A-5B and FIGS. 4A-4D than on similarities.

I/O system 504 includes: PO signal generator 210; gating signals generator 406; and a multi-gated I/O interface 508. Multi-gated I/O interface 508 includes: an output level shifter 518 coupled between output terminal 212 and a node 519; an output driver 520 coupled between node 519 and external terminal 214; an input buffer 522 coupled between external terminal 214 and a node 523; and an input level shifter 524 coupled between node 523 and input node of 216.

More particularly, multi-gated I/O interface 508 is configured to receive gating signals POC1′ and POC2′ as follows: output level shifter 518, output driver 520 and input buffer 522 are configured to receive gating signal POC1′ as an enablement signal; and input level shifter 524 is configured to receive gating signal POC2′ as an enablement signal. See, e.g., FIG. 5B for the relative timing of gating signals POC1′ and POC2′.

FIG. 5B is a graph of waveforms, in accordance with some embodiments.

More particularly, FIG. 5B is a graph of waveforms representing an input core data signal 552 on input terminal 216 of FIG. 5A which represents an output signal of input level shifter 524, PAD signal 553 on external terminal 214 of FIG. 5A, an enable signal 554 for input buffer 522, gating signal POC1′ waveform 555 and gating signal POC2′ waveform 556. In some embodiments, enable signal 554 is based on gating signal POC1′ waveform 555. In some embodiments, enable signal 554 is generated by one or more components (not shown) which are included in input buffer 522.

Each of PAD signal 553, gating signal POC1′ waveform 555 and gating signal POC2′ waveform 556 has a logical high value (or ‘logical one’ value) at a time T50. Each of input core data signal 552, and enable signal 554 for input buffer 522 has a logical low value (or ‘logical zero’ value) at a time T50.

At a time T51, gating signal POC1′ waveform 555 transitions to a logical low value, with a result that gating signal POC1′ waveform 555 enables input buffer 522, and also enables output level shifter 518 and output driver 520. Also at time T51: PAD signal 553 begins a slow transition 557 from the logical high value to the logical low value, reaching the logical low value at time T52; enable signal 554 for input buffer 522 begins a slow transition 559 from the logical low value to the logical high value, reaching the logical high value at time T52; and gating signal POC2′ waveform 556 remains at the logical high value, which prevents input core data signal 552 from otherwise experiencing a glitch 558. As glitch 558 does not actually occur, glitch 558 is shown with phantom (dashed) lines. Glitch 558 is represented by input core data signal 552 otherwise transitioning to the logical high value at time T51 and then returning to the logical low value at time T52.

More particularly, at time T51, by remaining at the logical high value, gating signal POC2′ waveform 556 continues to disable input level shifter 524 and thereby prevents enable signal 554 for input buffer 522 from following slow transition 557 of PAD signal 553 during T51-T52. If input buffer 522 otherwise was enabled at time T51 so that enable signal 554 for input buffer 522 instead followed slow transition 557 (again, from the logical low value to the logical high value) of PAD signal 553 during T51-T52, then input core data signal 552 otherwise would experience glitch 558. At a time T53, which is after PAD signal 553 has stabilized and thus after enable signal 554 for input buffer 522 has stabilized, gating signal POC2′ waveform 556 transitions to a logical low value, with a result that gating signal POC2′ waveform 556 enables input level shifter 524. As such, a benefit of I/O system 504 is that it avoids the second glitching issue suffered by the other approach because gating signals generator 406 is configured to enable input buffer 522 with gating signal POC1′ waveform 555, wait for output signal (not shown) of input buffer 522 to stabilize, and then enable input level shifter 524 with gating signal POC2′ waveform 556.

FIG. 6A is a flowchart of a method 600A of generating a layout diagram, in accordance with some embodiments.

In some embodiments, method 600A is used to generate a layout diagram corresponding to I/O system region 104 of FIG. 1. An example of a semiconductor device which can be manufactured according to method 600A includes semiconductor device 100 of FIG. 1.

Method 600A is implementable, for example, using EDA system 700 (FIG. 7, discussed below) and an integrated circuit (IC), manufacturing system 800 (FIG. 8), discussed below), in accordance with some embodiments. Regarding method 600, examples of the layout diagram include layout diagrams corresponding to the semiconductor devices disclosed herein, or the like.

In FIG. 6A, method 600A includes blocks 602-604. At block 602, a layout diagram is generated which, among other things, includes an I/O system corresponding to I/O system region 104, I/O system 204, I/O system 304, I/O system 404, I/O system 504, or the like. An example of a semiconductor device corresponding to a layout generated by method 600A includes semiconductor device 100 of FIG. 1. Block 602 is implementable, for example, using EDA system 700 (FIG. 7, discussed below), in accordance with some embodiments. From block 602, flow proceeds to block 604.

At block 604, based on the layout diagram, at least one of (A) one or more photolithographic exposures are made or (B) one or more semiconductor masks are fabricated or (C) one or more components in a layer of a semiconductor device are fabricated. See discussion below of FIG. 8.

FIG. 6B is a flowchart of a method 600B of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

Examples of the multi-gated I/O system for which method 600B generates gating signals include I/O system 204 of FIG. 2A, or the like.

In FIG. 6B, method 600B includes blocks 612-618. At block 612, an output level shifter is enabled. Examples of the output level shifter include output level shifter 218 of FIG. 2A, or the like. Examples of enabling the output level shifter include the transition of gating signal POC1 at time T1 in FIG. 2F, or the like. From block 612, flow proceeds to block 614.

At block 614, after the output signal of the output level shifter has stabilized, an output driver is enabled. Examples of the output driver include output driver 220 of FIG. 2A, or the like. Examples of enabling the output driver include the transition of gating signal POC2 at time T2 in FIG. 2F, or the like. From block 614, flow proceeds to block 616.

At block 616, after the output signal of the output driver has stabilized, an input buffer is enabled. Examples of the input buffer include input buffer 222 of FIG. 2A, or the like. Examples of enabling the input buffer include the transition of gating signal POC3 at time T3 in FIG. 2F, or the like. From block 616, flow proceeds to block 618.

At block 618, after the output signal of the input buffer has stabilized, the input level shifter is enabled. Examples of the input level shifter include input level shifter 224 of FIG. 2A, or the like. Examples of enabling the input level shifter include the transition of gating signal POC4 at time T4 in FIG. 2F, or the like.

FIG. 6C is a flowchart of a method 600C of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

Examples of the multi-gated I/O system for which method 600C generates gating signals include I/O system 304 of FIG. 3A, or the like.

In FIG. 6C, method 600C includes blocks 622-626. At block 622, an output level shifter is enabled. Examples of the output level shifter include output level shifter 318 of FIG. 3A, or the like. Examples of enabling the output level shifter include the transition of gating signal POC1′ at time T1 in FIG. 3C or the like. From block 622, flow proceeds to block 624.

At block 624, after the output signal of the output level shifter has stabilized, an output driver and an input buffer are enabled. Examples of the output driver include output driver 320 of FIG. 3A, or the like. Examples of the input buffer include input buffer 322 of FIG. 3A, or the like. Examples of enabling the output driver and the input buffer include the transition of gating signal POC2′ at time T2 in FIG. 3C, or the like. From block 624, flow proceeds to block 626.

At block 626, after the output signal of the input buffer has stabilized, the input level shifter is enabled. Examples of the input level shifter include input level shifter 324 of FIG. 3A, or the like. Examples of enabling the input level shifter include the transition of gating signal POC3′ at time T3 in FIG. 3C, or the like.

FIG. 6D is a flowchart of a method 600D of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

Examples of the multi-gated I/O system for which method 600D generates gating signals include I/O system 404 of FIG. 4A, or the like.

In FIG. 6D, method 600D includes blocks 632-634. At block 632, an output level shifter, an input buffer and an input level shifter are enabled. Examples of the output level shifter include output level shifter 418 of FIG. 4A, or the like. Examples of the input buffer include input buffer 422 of FIG. 4A, or the like. Examples of the input level shifter include input level shifter 424 of FIG. 4A, or the like.

Examples of enabling the output level shifter, the input buffer and the input level shifter include the transition of gating signal POC1′ at time T1 in FIG. 4C relative to FIG. 4A, or the like. From block 632, flow proceeds to block 634.

At block 634, after the output signal of the output level shifter has stabilized, an output driver is enabled. Examples of the output driver include output driver 420 of FIG. 4A, or the like. Examples of enabling the output driver include the transition of gating signal POC2′ at time T2 in FIG. 4C relative to FIG. 4A, or the like.

FIG. 6E is a flowchart of a method 600E of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

Examples of the multi-gated I/O system for which method 600E generates gating signals include I/O system 504 of FIG. 5A, or the like.

In FIG. 6E, method 600E includes blocks 642-644. At block 642, an output level shifter, an output driver and an input buffer are enabled. Examples of the output level shifter include output level shifter 518 of FIG. 5A, or the like. Examples of the output driver include output driver 520 of FIG. 5A, or the like. Examples of the input buffer include input buffer 522 of FIG. 5A, or the like. Examples of enabling the output level shifter include the transition of gating signal POC1′ at time T1 in FIG. 4C relative to FIG. 5A, or the like. From block 642, flow proceeds to block 644.

At block 644, after the output signal of the input buffer has stabilized, an input level shifter is enabled. Examples of the input level shifter include input level shifter 524 of FIG. 5A, or the like. Examples of enabling the input level shifter include the transition of gating signal POC2′ at time T2 in FIG. 4C relative to FIG. 5A, or the like.

FIG. 6F is a flowchart of a method 600F of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

In FIG. 6F, method 600F includes blocks 652-668. Examples of the multi-gated I/O system for which blocks 652-654 and 658-660 of method 600F generate gating signals include I/O system 204 of FIG. 2A, I/O system 304 of FIG. 3A, I/O system 404 of FIG. 4A, I/O system 504 of FIG. 5A, or the like. Examples of the multi-gated I/O system for which blocks 652-664 of method 600F generate gating signals include I/O system 204 of FIG. 2A, I/O system 304 of FIG. 3A, or the like. Examples of the multi-gated I/O system for which blocks 652-668 of method 600F generate gating signals include I/O system 204 of FIG. 2A, or the like.

At block 652, a power-on (PO) timing signal is delayed to produce a first delayed timing signal. An example of the PO timing signal is timing signal POC0 generated by PO signal generator 210 in FIGS. 2A, 3A, 4A and 5A, or the like. An example of the first delayed timing signal is timing signal POC0_D1 generated by delay cell 230(1) in FIGS. 2E and 3B, or the like. From block 652, flow proceeds to block 654.

At block 654, the first delayed timing signal is delayed to produce a second delayed timing signal. An example of the second delayed timing signal is timing signal POC0_D2 generated by delay cell 230(2) in FIGS. 2E and 3B, or the like. In some embodiments, e.g., I/O system 404 of FIG. 4A, I/O system 504 of FIG. 5A, or the like, flow proceeds from block 654 to block 658. In some embodiments, e.g., I/O system 204 of FIG. 2A, I/O system 304 of FIG. 3A, or the like, flow proceeds from block 654 to block 656.

At block 656, the second delayed timing signal is delayed to produce a third delayed timing signal. An example of the third delayed timing signal is timing signal POC0_D3 generated by delay cell 230(3) in FIG. 2E, or the like. From block 656, flow proceeds to block 658.

At block 658, first and second gating signals are generated correspondingly based on one or more of the POC timing signal, the first delayed timing signal or the second delayed timing signal. Examples of the first gating signal include gating signal POC1 of FIG. 2A, gating signal POC1′ of FIG. 3A, gating signal POC1′ of FIG. 4A, gating signal POC1′ of FIG. 5A, or the like. Examples of the second gating signal include gating signal POC2 of FIG. 2A, gating signal POC2′ of FIG. 3A, gating signal POC2′ of FIG. 4A, gating signal POC2′ of FIG. 5A, or the like. From block 658, flow proceeds to block 660.

At block 660, the first and second gating signals as provided to the output level shifter, the output driver, the input buffer or the input level shifter. Examples of providing the first gating signal correspondingly to the output level shifter, the output driver, the input buffer or the input level shifter include: providing gating signal POC1 to output level shifter 218 in FIG. 2A, providing gating signal POC1′ to output level shifter 318 in FIG. 3A, providing gating signal POC1′ to output level shifter 418, input buffer 422 and input level shifter 424 in FIG. 4A, providing gating signal POC1′ to output level shifter 518, output driver 520 and input buffer 522 in FIG. 5A, or the like. Examples of providing the second gating signal correspondingly to the output level shifter, the output driver, the input buffer or the input level shifter include: providing gating signal POC2 to output driver 220 in FIG. 2A, providing gating signal POC2′ to output driver 320 and input buffer 322 in FIG. 3A, providing gating signal POC2′ to output driver 420 in FIG. 4A, providing gating signal POC2′ to input level shifter 524 in FIG. 5A, or the like. From block 660, flow proceeds to block 662.

At block 662, a third gating signal is generated based on one or more of the POC timing signal, the first delayed timing signal or the second delayed timing signal. Examples of the third gating signal include gating signal POC3 of FIG. 2A, gating signal POC3′ of FIG. 3A, or the like. From block 662, flow proceeds to block 664.

At block 664, the third gating signal is supplied to the input buffer or the input level shifter. Examples of providing the third gating signal to the input buffer include providing gating signal POC3 to input buffer 222 of FIG. 2A, or the like. Examples of providing the third gating signal to the input level shifter include providing gating signal POC3′ to input level shifter 324 of FIG. 3A. From block 664, flow proceeds to block 666.

At block 666, a fourth gating signal is generated based on the POC timing signal and the third delayed timing signal. Examples of the fourth gating signal include gating signal POC4 of FIG. 2A, or the like. From block 666, flow proceeds to block 668.

At block 668, the fourth gating signal is supplied to the input level shifter. Examples of providing the fourth gating signal to the input level shifter include providing gating signal POC4 to input level shifter 224 of FIG. 2A, or the like.

FIG. 6G is a flowchart of a method 600G of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

More particularly, the flowchart of FIG. 6G shows additional blocks included in block 658 of FIG. 6F, in accordance with one or more embodiments. In FIG. 6G, block 658 includes blocks 670-672.

At block 670, the first gating signal is generated, more particularly, based on the POC timing signal and the third delayed timing signal. Examples of the first gating signal include gating signal POC1 of FIG. 2A, or the like. In some embodiments, the first gating signal is generated based on making a logical NOR combination. Examples of the first gating signal being based on a logical NOR combination include gating signal POC1 of FIGS. 2A and 2E (which is generated in part by NOR gate 236(1) of FIG. 2E), or the like. From block 670, flow proceeds to block 672.

At block 672, the second gating signal is generated based on the first delayed timing signal and the second delayed timing signal. Examples of the second gating signal include gating signal POC2 of FIG. 2A, or the like. In some embodiments, the second gating signal is generated based on making a logical NOR combination. Examples of the second gating signal being based on a logical NOR combination include gating signal POC2 of FIGS. 2A and 2E (which is generated in part by NOR gate 236(2) of FIG. 2E), or the like.

FIG. 6H is a flowchart of a method 600H of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

More particularly, the flowchart of FIG. 6H shows additional blocks included in block 662 of FIG. 6F, in accordance with one or more embodiments. In FIG. 6H, block 662 includes block 674.

At block 674, the third gating signal is generated, more particularly, based on the first delayed timing signal and the second delayed timing signal. Examples of the third gating signal include gating signal POC3 of FIG. 2A, or the like. In some embodiments, the third gating signal is generated based on making a logical NAND combination. Examples of the third gating signal being based on a logical NAND combination include gating signal POC3 of FIGS. 2A and 2E (which is generated in part by NAND gate 238(1) of FIG. 2E), or the like.

FIG. 6I is a flowchart of a method 600I of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

More particularly, the flowchart of FIG. 6I shows additional blocks included in block 664 of FIG. 6F, in accordance with one or more embodiments. In FIG. 6I, block 664 includes block 676.

At block 676, the fourth gating signal is generated, more particularly, based on the POC timing signal and the third delayed timing signal. Examples of the fourth gating signal include gating signal POC4 of FIG. 2A, or the like. In some embodiments, the fourth gating signal is generated based on making a logical NAND combination. Examples of the fourth signal being based on a logical NAND combination include gating signal POC4 of FIGS. 2A and 2E (which is generated in part by NAND gate 238(2) of FIG. 2E), or the like.

FIG. 6J is a flowchart of a method 600J of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

More particularly, the flowchart of FIG. 6J shows additional blocks included in block 658 of FIG. 6F, in accordance with one or more embodiments. In FIG. 6J, block 658 includes blocks 680-682.

At block 680, the first gating signal is generated, more particularly, based on the POC timing signal and the second delayed timing signal. Examples of the first gating signal include gating signal POC1′ of FIG. 3A, gating signal POC1′ of FIG. 4A, gating signal POC1′ of FIG. 5A, or the like. In some embodiments, the first gating signal is generated based on making a logical NOR combination. Examples of the first gating signal being based on a logical NOR combination include gating signal POC1′ of FIGS. 3A and 3B (which is generated in part by NOR gate 336(3) of FIG. 3B), gating signal POC1′ of FIGS. 4A and 4B (which is generated in part by NOR gate 336(3) of FIG. 4B), or the like. From block 680, flow proceeds to block 682.

At block 682, the second gating signal is generated based on the first delayed timing signal. Examples of the second gating signal include gating signal POC2′ of FIG. 3A, gating signal POC2′ of FIG. 4A, gating signal POC2′ of FIG. 5A, or the like. In some embodiments, the second gating signal is generated based on making a logical inversion. Examples of the second gating signal being based on a logical inversion include gating signal POC2′ of FIGS. 3A and 3B (which is generated in part by inverter 334(11) of FIG. 3B), gating signal POC2′ of FIGS. 4A and 4B (which is generated in part by inverter 334(11) of FIG. 4B), or the like.

FIG. 6K is a flowchart of a method 600K of generating gating signals for a multi-gated I/O system, in accordance with some embodiments.

More particularly, the flowchart of FIG. 6K shows additional blocks included in block 662 of FIG. 6F, in accordance with one or more embodiments. In FIG. 6K, block 662 includes block 684.

At block 684, the third gating signal is generated, more particularly, based on the POC timing signal and the second delayed timing signal. Examples of the third gating signal include gating signal POC3′ of FIG. 3B, or the like. In some embodiments, the third gating signal is generated based on making a logical NAND combination. Examples of the third gating signal being based on a logical NAND combination include gating signal POC3′ of FIGS. 3A and 3B (which is generated in part by NAND gate 338(3) of FIG. 3B), or the like.

FIG. 7 is a block diagram of an electronic design automation (EDA) system 700 in accordance with some embodiments.

In some embodiments, EDA system 700 includes an APR system. Methods described herein of designing layout diagrams represent wire routing arrangements, in accordance with one or more embodiments, are implementable, for example, using EDA system 700, in accordance with some embodiments.

In some embodiments, EDA system 700 is a general purpose computing device including a hardware processor 702 and a non-transitory, computer-readable storage medium 704. Storage medium 704, amongst other things, is encoded with, i.e., stores, computer program code 706, i.e., a set of computer-executable instructions. Execution of instructions 706 by hardware processor 702 represents (at least in part) an EDA tool which implements a portion or all of the methods described herein in accordance with one or more embodiments (hereinafter, the noted processes and/or methods).

Processor 702 is electrically coupled to computer-readable storage medium 704 via a bus 708. Processor 702 is also electrically coupled to an I/O interface 710 by bus 708. A network interface 712 is also electrically connected to processor 702 via bus 708. Network interface 712 is connected to a network 714, so that processor 702 and computer-readable storage medium 704 are capable of connecting to external elements via network 714. Processor 702 is configured to execute computer program code 706 encoded in computer-readable storage medium 704 in order to cause system 700 to be usable for performing a portion or all of the noted processes and/or methods. In one or more embodiments, processor 702 is a central processing unit (CPU), a multi-processor, a distributed processing system, an application specific integrated circuit (ASIC), and/or a suitable processing unit.

In one or more embodiments, computer-readable storage medium 704 is an electronic, magnetic, optical, electromagnetic, infrared, and/or a semiconductor system (or apparatus or device). For example, computer-readable storage medium 704 includes a semiconductor or solid-state memory, a magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disk, and/or an optical disk. In one or more embodiments using optical disks, computer-readable storage medium 704 includes a compact disk-read only memory (CD-ROM), a compact disk-read/write (CD-R/W), and/or a digital video disc (DVD).

In one or more embodiments, storage medium 704 stores computer program code 706 configured to cause system 700 (where such execution represents (at least in part) the EDA tool) to be usable for performing a portion or all of the noted processes and/or methods. In one or more embodiments, storage medium 704 also stores information which facilitates performing a portion or all of the noted processes and/or methods. In one or more embodiments, storage medium 704 stores library 707 of standard cells including such standard cells as disclosed herein.

EDA system 700 includes I/O interface 710. I/O interface 710 is coupled to external circuitry. In one or more embodiments, I/O interface 710 includes a keyboard, keypad, mouse, trackball, trackpad, touchscreen, and/or cursor direction keys for communicating information and commands to processor 702.

EDA system 700 also includes network interface 712 coupled to processor 702. Network interface 712 allows system 700 to communicate with network 714, to which one or more other computer systems are connected. Network interface 712 includes wireless network interfaces such as BLUETOOTH, WIFI, WIMAX, GPRS, or WCDMA; or wired network interfaces such as ETHERNET, USB, or IEEE-1364. In one or more embodiments, a portion or all of noted processes and/or methods, is implemented in two or more systems 700.

System 700 is configured to receive information through I/O interface 710. The information received through I/O interface 710 includes one or more of instructions, data, design rules, libraries of standard cells, and/or other parameters for processing by processor 702. The information is transferred to processor 702 via bus 708. EDA system 700 is configured to receive information related to a UI through I/O interface 710. The information is stored in computer-readable medium 704 as user interface (UI) 742.

In some embodiments, a portion or all of the noted processes and/or methods is implemented as a standalone software application for execution by a processor. In some embodiments, a portion or all of the noted processes and/or methods is implemented as a software application that is a part of an additional software application. In some embodiments, a portion or all of the noted processes and/or methods is implemented as a plug-in to a software application. In some embodiments, at least one of the noted processes and/or methods is implemented as a software application that is a portion of an EDA tool. In some embodiments, a portion or all of the noted processes and/or methods is implemented as a software application that is used by EDA system 700. In some embodiments, a layout diagram which includes standard cells is generated using a tool such as VIRTUOSO® available from CADENCE DESIGN SYSTEMS, Inc., or another suitable layout generating tool.

In some embodiments, the processes are realized as functions of a program stored in a non-transitory computer readable recording medium. Examples of a non-transitory computer readable recording medium include, but are not limited to, external/removable and/or internal/built-in storage or memory unit, e.g., one or more of an optical disk, such as a DVD, a magnetic disk, such as a hard disk, a semiconductor memory, such as a ROM, a RAM, a memory card, and the like.

FIG. 8 is a block diagram of an integrated circuit (IC) manufacturing system 800, and an IC manufacturing flow associated therewith, in accordance with some embodiments. In some embodiments, based on a layout diagram, at least one of (A) one or more semiconductor masks or (B) at least one component in a layer of a semiconductor integrated circuit is fabricated using manufacturing system 800.

In FIG. 8, IC manufacturing system 800 includes entities, such as a design house 820, a mask house 830, and an IC manufacturer/fabricator (“fab”) 850, that interact with one another in the design, development, and manufacturing cycles and/or services related to manufacturing an IC device 860. The entities in system 800 are connected by a communications network. In some embodiments, the communications network is a single network. In some embodiments, the communications network is a variety of different networks, such as an intranet and the Internet. The communications network includes wired and/or wireless communication channels. Each entity interacts with one or more of the other entities and provides services to and/or receives services from one or more of the other entities. In some embodiments, two or more of design house 820, mask house 830, and IC fab 850 is owned by a single larger company. In some embodiments, two or more of design house 820, mask house 830, and IC fab 850 coexist in a common facility and use common resources.

Design house (or design team) 820 generates an IC design layout diagram 822. IC design layout diagram 822 includes various geometrical patterns designed for an IC device 860. The geometrical patterns correspond to patterns of metal, oxide, or semiconductor layers that make up the various components of IC device 860 to be fabricated. The various layers combine to form various IC features. For example, a portion of IC design layout diagram 822 includes various IC features, such as an active region, gate electrode, source and drain, metal lines or vias of an interlayer interconnection, and openings for bonding pads, to be formed in a semiconductor substrate (such as a silicon wafer) and various material layers disposed on the semiconductor substrate. Design house 820 implements a proper design procedure to form IC design layout diagram 822. The design procedure includes one or more of logic design, physical design or place and route. IC design layout diagram 822 is presented in one or more data files having information of the geometrical patterns. For example, IC design layout diagram