234 may be configured to drive the data signals along the corresponding die interconnects 220. In some embodiments, a single data conduit 232 or driver 234 may be in electrical communication with multiple die interconnects 220, each of which may be in electrical communication with different array dies 210.

Each of the data conduits 232 may be configured to receive the data signal from a common source. For instance, the data conduit 232a and the data conduit 232b may each receive a substantially similar, if not identical, data signal from the same signal source (e.g. the data signal corresponding to the same data bit). The source of the data signal may include a data path, a driver, a latch, a pin, or any other construct that may provide a data signal to a data conduit.

The data conduits 232 may each be subject to a load. Although not limited as such, this load may be measured as a capacitive load, such as a parasitic capacitance. The load on each of the data conduits 232 may include at least a load of the die interconnect 220 to which the data conduit 232 is coupled or connected as well as a load of each array die 210 with which the die interconnect 220 is in electrical communication via a data port of the die interconnect 220. Thus, for example, the load of the data conduit 232a may include loads of the die interconnect 220a, the array die 210a, and the array die 210b. Similarly, the load of the data conduit 232b may include loads of the die interconnect 220b, the array die 210c, and the array die 210d.

Generally, a load that would be on a data conduit that was in electrical communication with a die interconnect that was in electrical communication with at least one data port of each of the array dies 210 can be considered the maximum load for a data conduit. This maximum load is the load of a data conduit of a memory package that does not implement the teachings of this disclosure, but is in accordance with conventional configurations.

In some implementations, the difference between the load of the data conduit 232a and the load of the data conduit 232b is less than the maximum load for a data conduit as described above. Thus, in some cases, there may exist a degree of balance or equalization between the loads of the data conduits 232a, 232b. In some implementations, the difference between the load of the data conduit 232a and the load of the data conduit 232b is zero or substantially zero. In some embodiments, the length of each die interconnect 220, and the number of array dies 210 in electrical communication with each die interconnect 220 may be selected to maintain the difference between the load of the data conduit 232a and the load of the data conduit 232b to be at or below a threshold load difference. For example, suppose that the load of each array die 210 is 1, the load of each segment of the die interconnects 220 is 0.25, and that the threshold load difference is 0.5. Using the configuration schematically illustrated in FIG. 2, the load on the data conduit 232a in this example is 2.5 and the load on the data conduit 232b in this example is 3. Thus, in this example, the difference between the load of the data conduit 232a and the load of the data conduit 232b is at the threshold load difference value of 0.5. However, an alternative configuration that places the die interconnect 220a in electrical communication with only the array die 210a, and the die interconnect 220b in electrical communication with the array dies 210b-210d would not satisfy the threshold load difference value of 0.5 of the above example. In the alternative configuration, the load on the data conduit 232a would be 1.25 and the load on the data conduit 232b would be 4. Thus, in the alternative configuration, the difference between the load of the data conduit 232a and the load of the data conduit 232b is 2.75, which is above the threshold load difference value of 0.5.

For certain embodiments, the load of each data conduit is less than the maximum load as described above. Thus, in some cases, the load of the data conduit 232a is less than the maximum load and the load of the data conduit 232b is less than the maximum load. Further, in many implementations, the combined load of the data conduit 232a and the data conduit 232b is less than the maximum load of a single data conduit. In other words, it is possible to design the data conduit 232a and the data conduit 232b to reduce the overall load compared to a single data conduit that is in electrical communication with a die interconnect that is in electrical communication with at least one data port of each of the array dies 210. By reducing the overall load compared to the single data conduit, it is possible in many cases to reduce power consumption. Further, it is possible in many cases to maintain signal quality (e.g. maintain signal amplitude, maintain low signal distortion, etc.) while reducing power consumption. Advantageously, in a number of embodiments, by using multiple data conduits instead of a single data conduit, the speed of the memory package 200 can be increased. In some cases, this speed increase can include a reduced latency in accessing array dies 210 and/or operating the memory package 200 at a higher clock frequency.

Each of the die interconnects 220 may include any type of conducting material. For example, the die interconnects 220 may include copper, gold, or a conductive alloy, such as a copper/silver alloy. Further, the die interconnects 220 may include any type of structure for enabling electrical communication between the data conduits 232 and the data ports of the array dies 210. For example, the die interconnects 220 may include a wire, a conducting rod, or a conducting trace, to name a few. Moreover, the die interconnects 220 may use vias, or through-silicon vias (TSVs) to couple with or to electrically communicate with an array die. For instance, die interconnect 220a may be connected with data ports of the array dies 210a and 210b using vias (illustrated by the filled or darkened circles). Examples of TSVs which may be used with the present disclosure are described further in U.S. Pat. Nos. 7,633,165 and 7,683,459.

In addition, the die interconnects 220 may use via holes to pass through an array die that is configured to not be in electrical communication with the die interconnect. For instance, die interconnect 220b may pass through array dies 210a and 210b using TSVs that do not enable electrical communication between the die interconnect 220b and data ports of the array dies 210a and 210b (illustrated by the unfilled circles). In this way, the array dies 210a, 210b are not responsive to the data signals being transmitted by the die interconnect 220b. However, the die interconnect 220b may be connected with at least one data port of each of the array dies 210c and 210d using a via (illustrated by the filled or darkened circles). In cases where the die interconnect passes through an array die that is configured to not be in electrical communication with the die interconnect, the TSV may include an insulator or an air gap between the die interconnect and the array die circuitry that is large enough to prevent electrical communication between the die interconnect and the array die circuitry. In certain embodiments, the TSV for array dies that are configured to be in electrical communication with the die interconnect and for array dies that are configured to not be in electrical communication with the die interconnect may be configured the same. However, in such cases, electrical connections leading from the TSV of the array dies that are configured to not be in electrical communication with the die interconnect may not exist or may be stubs. These stubs are configured to not provide electrical communication with the memory cells of the array die.

Although FIG. 2 illustrates a single pair of data conduits 232 corresponding to a single pair of die interconnects 220, this is only to simplify the drawing figure. The memory package 200 may generally include as many additional data conduits and corresponding die interconnects as the number of bits the memory package 200 is designed or configured to support per memory address. Thus, if, for example, the memory package 200 is configured to be a 16-bit memory, the memory package 200 may include 16 pairs of data conduits 232 and 16 pairs of corresponding die interconnects 220. Similarly, if the memory package 200 is configured as a 32- or 64-bit memory, the memory package 200 may include 32 or 64 pairs of data conduits 232 and 32 or 64 pairs of corresponding die interconnects 220. Thus, for the memory package 200, each data conduit is configured to be in electrical communication with a die interconnect that is configured to be in electrical communication with a pair of the array dies 210. However, it is possible that, in some embodiments, the data conduits and die interconnects of different bits may be configured differently.

In certain embodiments, the same die interconnects and the same corresponding data conduits may be used to transfer data both to and from the array dies 210. In such embodiments, the die interconnects may be bi-directional. In alternative embodiments, separate die interconnects and corresponding data conduits may be used to transfer data to the array dies 210 and data from the array dies 210 to the control die 230. Thus, such embodiments may include double the number of die interconnects and data conduits as embodiments that use the same die interconnect to transfer data to and from an array die.

In some embodiments, the control die 230 may include additional command/address conduits 240 and die interconnects 242, which may be in electrical communication with at least one port of each of the array dies 210. For simplicity, FIG. 2 shows only a single such conduit 240 and die interconnect 242. The command/address conduits 240 are configured to provide corresponding signals to the die interconnects 242. These signals may be command signals, address signals, or may serve as both command and address signals (e.g., may include a memory cell address and a write command or a read command) either simultaneously or based on a determining criterion, such as the edge of a clock signal. The command die 230 may include a command/address conduit 240 and corresponding die interconnect 242 for each bit of the command/address signals that the memory package 200 is configured to support. The number of bits of the command/address signals may be the same or may be different from the number of data bits of the memory package 200.

In addition, in certain embodiments, the control die 230 may include a plurality of chip select conduits 250 (e.g., chip select conduits 250a-250d as shown in FIG. 2). Further, the control die 230 may include corresponding die interconnects 252 (e.g., die interconnects 252a-252d) with one die interconnect 252 in electrical communication with one chip select conduit 250 and one array die 210. Each of the die interconnects 252 may be in electrical communication with a different array die 210. For example, the die interconnect 252a may be in electrical communication with the array die 210a and the die interconnect 252b may be in electrical communication with the array die 210b. Each of the chip select conduits 250 may be configured to provide a chip select signal to a corresponding array die 210 via a corresponding die interconnect 252.

In some embodiments, the control die 230 may include additional drivers that are configured to drive the chip select signals along the die interconnects 252. Alternatively, the chip select signals may be driven by drivers that are external to the control die 230. For example, a register (not shown) that is part of a memory module that includes the memory package 200 may determine the chip select signals and drive the chip select signals to the array dies 210. As a second example, the chip select signals may be provided by an MCH. In some embodiments, the control die 230 may determine the array die 210 to select based on, for example, an address signal. In such embodiments, the control die may generate the chip select signals.

FIG. 3 schematically illustrates another example embodiment of a memory package 300 in accordance with the present disclosure. In certain embodiments, some or all of the embodiments described above with respect to the memory package 200 may be applicable to the memory package 300. However, for ease of illustration and to simplify discussion, certain elements are omitted in FIG. 3, such as the chip select conduits. Nevertheless, it should be understood that the memory package 300 can include the same or similar elements as described above with respect to the memory package 200, including, for example, the chip select conduits.

The memory package 300 may include a plurality of array dies 310 (e.g., array dies 310a-310h). In the implementation illustrated in FIG. 3, the memory package includes eight array dies. However, as stated earlier, the memory package 300 may include more or fewer array dies. Each of the array dies 310 may include one or more ports (not shown) that enable electrical communication between the circuitry of the array dies 310 and one or more die interconnects 320. Each of these die interconnects 320 may be coupled to, or in electrical communication with at least one port of at least one of the array dies 310. As with the memory package 200, in certain embodiments, at least one of the die interconnects 320 is in electrical communication with at least one port from each of at least two array dies 310 without being in electrical communication with a port from at least one array die 310, which may be in electrical communication with a different die interconnect 320.

In addition to the plurality of array dies 310, the memory package 300 includes a control die 330. In some embodiments, the control die 330 may include a number of conduits 332 (e.g., conduits 332a-332f). Each of these conduits 332 may be configured to transmit a signal to a single die interconnect 320.

Further, implementations of the conduits 332 may include one or more drivers 334 (e.g., drivers 334a-334f). Each of the drivers 334 may be configured to drive a signal along a corresponding die interconnect 320. For instance, the driver 334a of the conduit 332a may be configured to drive a signal along the die interconnect 320a to one or more of the array dies 310a and 310b. As a second example, the driver 334b of the conduit 332b may be configured to drive a signal along the die interconnect 320b to one or more of the array dies 310c and 310d. Although the die interconnect 320b may pass through the array dies 310a and 310b, because the die interconnect 320b, in the example illustrated in FIG. 3, is configured to not be in electrical communication with the array dies 310a and 310b, the driver 334b does not drive the signal to the array dies 310a and 310b.

In some embodiments, the signal can be a data signal, a command or address signal, a chip select signal, a supply voltage signal, or a ground voltage signal, to name a few. Further, as the signal is not limited to a data signal, in some embodiments, the conduits 332 may include conduits configured to provide signals other than data signals to the die interconnects 320. For example, the conduits may include conduits configured to provide a command or address signal, a chip select signal, a supply voltage signal, or a ground voltage signal to one or more die interconnects. Consequently, in some embodiments, the drivers 334 may be configured to drive signals other than data signals.

Generally, the signal that each of the drivers 334 drive to the corresponding die interconnects 320 is from a common source. Thus, each of the drivers 334, in certain embodiments, is driving the same signal to each corresponding die interconnect 320.

The size of the drivers 334 is generally related to the load on the driver 334. In certain embodiments, the load on each driver 334 corresponds to the load of the respective conduit 332. Although not limited as such, the load may be measured as a capacitive load, such as a parasitic capacitance.

The load on each of the conduits 332 may include at least the loads of the die interconnect 320 with which the conduit 332 is coupled or/address as well as the loads of each array die 310 with which the die interconnect 320 is in electrical communication via a port of the die interconnect 320. Thus, for example, the loads of the conduit 332a may include the loads of the die interconnect 320a, the array die 310a, and the array die 310b. Similarly, the loads of the conduit 332b may include the loads of the die interconnect 320b, the array die 310c, and the array die 310d. The loads of both conduits 332a and 332b include a load of two array dies 310 because the corresponding die interconnects 320 are each configured to be in electrical communication with two array dies 310. On the other hand, the load of the conduit 332c, which may include the loads of the die interconnect 320c and the array die 310e, includes a load of one array die 310e because the corresponding die interconnect 320c is configured to be in electrical communication with only one array die 310.

As previously described with respect to FIG. 2, a load that would be on a conduit that was in electrical communication with a die interconnect that was in electrical communication with at least one port of each of the array dies 310 can be considered the maximum load for a conduit. This maximum load is the load of a conduit of a memory package that does not implement the teachings of this disclosure, but is used in accordance with conventional configurations.

In some implementations, the difference between the loads of any pair of the conduits 332 is less than the maximum load for a conduit as described above. For instance, the difference between the load of the conduit 332a and the load of the conduit 332b is less than the maximum load. As a second example, the difference between the load of the conduit 334f and any one of the conduits 334a to 334e is less than the maximum load. Thus, in some cases, the load on each of the conduits 332 may be, at least partially balanced or equalized to reduce or minimize the difference between the load of any pair of the conduits 332. In some implementations, the difference between the load of a pair of the conduits 332 is zero or substantially zero. In some embodiments, the length of each die interconnect 320, and the number of array dies 310 in electrical communication with each die interconnect 320 may be selected to maintain the difference between the load of any pair of the conduits 332 to be at or below a threshold load difference.

For certain embodiments, the load of each conduit is less than the maximum load as described above. Thus, for example, the load of the conduit 332a, the load of the conduit 332b, and the load of the conduit 332c are each less than the maximum load defined above.

In certain embodiments, the load associated with each of the array dies 310 may be substantially equivalent. For example, the load of the array die 310a may be substantially equal to the load of the array die 310h. Thus, the load contribution from the array dies 310 for a specific conduit 332 may be measured as a multiple of the array dies that are in electrical communication with a die interconnect 320 corresponding to a specific conduit 332. For example, assuming that the load of each of the array dies 310 is ‘L’, then the contribution of the load from the array dies 310 to the conduit 332a would be 2 L because the die interconnect 320a corresponding to the conduit 332a is in electrical communication with two array dies 310, array dies 310a and 310b. In alternative embodiments, the load of each of the array dies 310a may differ. For example, the load of array die 310a may be L and the load of the array die 310b may be 1.25 L.

Similar to the array dies 310, in some embodiments, a die interconnect 320 can be considered to comprise a plurality of segments, with each segment of a die interconnect 320 contributing a substantially equivalent load to the load of the die interconnect 320. In this case, the segment of the die interconnect 320 may refer to the portion of the die interconnect between two successive or adjacent dies (array die-to-array die, master die-to-array die, or both) along the die interconnect 320. Further, the segment may be defined as a portion of the die interconnect 320 between the dies exclusive of a portion of the dies. For example, one segment of the die interconnect 320a may extend from the top of the array die 310a to the bottom of the array die 310b. Alternatively, the segment may be defined to include at least a portion of at least one of the array dies 310. For example, one segment of the die interconnect 320a may extend from the center of array die 310a to the center of array die 310b. As a second example, one segment of the die interconnect 320a may extend from the top of the control die 330 to the top of the array die 310a, and therefore may include a portion of the die interconnect 320a extending from the bottom of the array die 310a to the top of the array die 310a. In some implementations, the segments are substantially equal in length to each other. Moreover, the load contribution of each segment may be substantially equal to each other. Alternatively, the segments may be unequal in length and/or may each contribute a different load to the total load of a die interconnect 320. Further, in some cases, the load contribution of a segment of the die interconnect 320 that is in electrical communication with a port of an array die 310 may differ from the load contribution of a segment of the die interconnect 320 that is not in electrical communication with a port of an array die 310.

In some cases, the load contribution of each segment of the die interconnect 320 may be measured as a fraction of the load contribution from an array die 310. For example, the load of one segment of the die interconnect 320a may be equivalent to one quarter of the load of an array die 310. Thus, for example, the load of the conduit 332a may be 2.5 L assuming a load contribution of L per array die 310 (two in this case) in electrical communication with the die interconnect 320a and a load contribution of 0.25 L per segment (two in this case) of the die interconnect 320a. As a second example, the load of the conduit 332f may be 3 L assuming the same load values as the previous example and a load contribution from one array die 310h and eight die interconnect 320f segments. Table 1 specifies the capacitive load values for each conduit 332 assuming, as with the previous two examples, that the load of each of the array dies 310 is L, and that the load of each segment of the die interconnects 320 is 0.25 L. Table 1 also specifies the deviation in load from the conduits having the highest load value, which in this example are conduits 332b and 332f.

TABLE 1

Number of
Number of Die
Capacitive
Deviation from

Conduit
Array Dies
Interconnect Segments
Load
Maximum Load

332a
2
2
2.5 L
0.5

332b
2
4
3 L
0

332c
1
5
2.25 L
0.75

332d
1
6
2.5 L
0.5

332e
1
7
2.75 L
0.25

332f
1
8
3 L
0

As can be seen from Table 1, the maximum load of any conduit 332, using the example values previously described, is 3 L, or rather three times the load of a single array die 310. Assuming the same example values, the load of a conduit in electrical communication with a die interconnect that itself is in electrical communication with each array die 310 would be 10 L. Thus, certain embodiments of the present disclosure enable a reduction in the load of the conduits 332. Consequently, in some embodiments, the drivers 334 may each be smaller than a single driver that is configured to drive a signal from a conduit along a single die interconnect that is in electrical communication with a port from each of the array dies 310. Moreover, the drivers 334 may include smaller transistor sizes than a single driver that is configured to drive a signal to each of the array dies 110.

As can be seen from Table 1, conduits 332b and 332f have the largest capacitive load of the group of conduits, which is 3 L. Conduit 332 has the smallest capacitive load of the group of conduits, which is 2.25 L and which is a deviation of only 0.75 from the maximum load. Thus, in some embodiments, each of the drivers 334 may be substantially similar in size. In certain implementations, the drivers 334 may vary in size based on the total capacitive load on each conduit 332. Thus, the driver 334f may be larger than the driver 334e. Alternatively, each driver 334 may be substantially equal and may be configured based on the drivers 334 with the largest load, which are drivers 334b and 334f in the example illustrated in FIG. 3 and Table 1.

In some embodiments, the capacitive load of each conduit 332 or driver 334 can be calculated using formula (1).

C
⁢
L

=

A
⁢
D

+

S
/
M

(
1
)

In formula (1), CL represents the capacitive load of a conduit 332 or driver 334, AD represents the number of array dies 310 in electrical communication with a die interconnect 320 that is in electrical communication with the conduit 332 and/or driver 334, S represents the number of die interconnect segments of the die interconnect 320, and M represents the ratio of the load of an array die 310 to the load of a segment of a die interconnect 320. Thus, using formula (1) and the example values described above, the load of the driver 332a, for example, can be calculated with the following values: AD=2, for two array dies 310; S=2, for the two segments of the die interconnect 320a; and M=4, for the ratio of the load of an array die 310, L, to the load of a segment of the die interconnect 320a, 0.25L. Therefore, as can be seen from Table 1, the capacitive load of the driver 332a is 2.5 L where L is the load of a single array die.

In some cases, the load on each conduit 332 and/or driver 334 may be evenly balanced. In other words, the load on each conduit 332 and/or driver 334 may be substantially the same. To achieve a balanced load, each of the conduits 332 may be in electrical communication with a combination of array dies 310 and die interconnect 320 segments that results in a load that is substantially equivalent to the loads of the other conduits 332. In certain embodiments, the load of the conduits 332 is balanced despite each conduit 332 being in electrical communication with a different subset of the array dies 310. However, in alternative embodiments, the load of each conduit 332 and/or driver 334 may differ. This difference in the load of the conduits 332 and/or drivers 334 may be a design decision (e.g. to maintain a specific number of drivers). Alternatively, or in addition, the load difference between conduits 332 and/or drivers 334 may occur because the loads of the array dies 310 and the die interconnect segments 320 do not allow for perfect or substantially even load balancing.

As previously stated, in some embodiments the loads of the conduits 332 and/or drivers 334 may be balanced to minimize the difference between any pair of conduits 332 and/or drivers 334. For example, as illustrated in FIG. 3, a driver in electrical communication with a longer die interconnect, which may consequently include more die interconnect segments, is likely to obtain a larger load contribution from the die interconnect than a driver in electrical communication with a shorter die interconnect (e.g., compare driver 334f to 334a). Thus, the driver in electrical communication with the longer die interconnect may be in electrical communication with fewer array dies than the driver in electrical communication with the shorter die interconnect (e.g. compare driver 334f to 334a). The selection of die interconnect length and the selection of array dies to place in electrical communication with the die interconnects may therefore be dependent on the load of each segment of the die interconnects 320 and the loads of the array dies 310.

Alternatively, or in addition, the loads of the conduits 332 and/or drivers 334 may be balanced to reduce the maximum load of each conduit 332 and/or driver 334. Further, in some embodiments, the maximum load of each conduit 332 and/or driver 334 may be reduced to maintain the load of each conduit 332 and/or driver 334 to be at or below a threshold load difference.

Although not illustrated in FIG. 3, each of the conduits 332 may include one or more additional drivers configured to drive a signal received from an array die via a corresponding die interconnect 320. The additional drivers may drive the signal to a processor, a register, a latch, or any other component or device that may or may not be part of a memory module that includes the memory package 300. In some implementations, one or more of the die interconnects 320 are configured to be bi-directional, thereby enabling a signal to be driven to the array dies 310 via the die interconnect 320, and to enable a signal received from the array dies 310 along the die interconnect 320 to be transmitted to a corresponding conduit 332 of the control die 330. Alternatively, the memory package 300 comprises one or more die interconnects 320 that are configured to enable a signal to be driven to the array dies 310 without enabling a signal to be received from the array dies 310 (e.g., the die interconnects 320 may not be bi-directional). In certain embodiments where one or more of the die interconnects 320 are not bi-directional, the memory package 300 may include additional die interconnects (not shown) that are in electrical communication with the one or more additional conduits or drivers and that are configured to enable a signal from the array dies 310 to be transmitted to the one or more additional conduits or drivers.

In addition to the drivers 334 of the control die 330, the memory package 300 may include one or more pre-drivers 340. A pre-driver 340, shown schematically in FIG. 3, may be large enough to drive a signal (e.g., a data signal) to any of the drivers 332 and subsequently, to any of the array dies 310. Thus, using the same example values as described above in relation to Table 1, a load of the pre-driver 340 may be at least 10 L, which is the load of a conduit in electrical communication with a die interconnect that is in electrical communication with a port from each of the array dies 310. In some embodiments, the memory package 300 may include any number of additional drivers and/or latches for buffering and/or driving the signal to any of the array dies 310.

Just as the memory package 300 may include a pre-driver 340 for providing a signal to the conduits 332, the memory package 300 may include a post-driver (not shown) for driving an output signal from the control die 330. This post-driver may drive the output signal to additional latches and/or drivers. In some embodiments, the post-driver may drive the signal from the memory package 300 to a bus or other electrical path that is in electrical communication with the memory package 300.

FIG. 4 illustrates an example embodiment of a driver structure 400 of a control die (e.g. control die 230) in accordance with the present disclosure. The driver structure 400 is configured for a single data bit. Thus, a control die for a 32-bit memory package will generally include at least 32 instances of the driver structure 400, one per bit. In some embodiments, the control die 230 may include the driver structure 400 in place of the combination of drivers 232a and 232b. Similarly, in certain embodiments, the control die 330 may include a structure similar to the driver structure 400 in place of the drivers 334. In such embodiments, the driver structure 400 would be modified to enable a signal (e.g., data signal) to be driven to the six conduits 332.

The driver structure 400 can include an input/output port 402 configured to receive or send a signal, such as a data signal. Signals received at the input/output port 402 can be provided to the drivers 404a and 404b. In turn, these drivers 404a and 404b can drive the signal to conduits 406a and 406b respectively, which are in electrical communication with corresponding die interconnects. Each of the die interconnects may be in electrical communication with different array dies in accordance with certain embodiments described herein.

In some embodiments, the driver structure 400 is bi-directional. In such embodiments, operation of the drivers 404a and 404b, and 408a and 408b may be controlled or enabled by a control signal (e.g., a directional control signal). This control signal, in some cases, may correspond to one or more of a command/address signal (e.g., read/write) and a chip select signal. In some implementations, the drivers 404a and 404b may drive a signal to the array die corresponding to the chip select signal, and not to array dies that do not correspond to a chip select signal. For example, suppose the conduit 406a is in electrical communication with array dies one and two (not shown), and that the conduit 406b is in electrical communication with array dies three and four (not shown). If a chip select signal is received corresponding to array die two, then in some implementations, driver 404a may be configured to drive a signal along a die interconnect in electrical communication with the conduit 406a to array die one and two. In this example, the driver 404b would not drive the signal because the chip select signal does not correspond to either array die three or array die four.

In some embodiments, the drivers 404a and 404b may drive a signal to all of the array dies. For example, assume the memory package that includes the driver structure 400 also includes four array dies. If the die interconnect in electrical communication with the conduit 406a is in electrical communication with two of the array dies, and if the die interconnect in electrical communication with the conduit 406b is in electrical communication with the other two array dies, then the drivers 404a and 404b may drive a signal to all four of the array dies of this example.

Similar to the input/output port 402, the conduits 406a and 406b can be configured to receive a signal from the die interconnects that are in electrical communication with the conduits 406a and 406b. In turn, the signal received at one of the conduits 406a and 406b can be provided to drivers 408a and 408b respectively. The drivers 408a and 408b can each be configured to drive a signal received from a respective data conduit 406a and 406b to the input/output port 402 and to another component that may be in electrical communication with the input/output port 402, such as a MCH.

In some embodiments, one or more chip selects, as illustrated in FIG. 2, may be used to select, determine, or enable the array die that communicates the signal to or from one or more of the conduits 406a and 406b and the drivers 408a and 408b. Similarly, in some embodiments, the chip select may select, determine, or enable the array die to receive and/or respond to the signal driven by the drivers 404a and 404b to the array dies.

It should be noted that the driver structure 400 is a non-limiting example for arranging drivers in a control die. Other driver structures are possible. For example, instead of the drivers 404a and 408a being in electrical communication with the same conduit 406a, each of the drivers 404a and 408a can be in electrical communication with a separate conduit and consequently a separate die interconnect. In such an example, the drivers 404a and 408a may still be in electrical communication with the same input/output port 402, or each driver may be in electrical communication with a separate port, the driver 404a in electrical communication with an input port, and the driver 408a in communication with an output port.

FIG. 5 presents a flowchart for an example embodiment of a load optimization process 500. In certain embodiments, the load optimization process 500 may be performed, at least in part, by one or more computing systems. Further, the process 500, in some embodiments, may be used to optimize one or more loads in a memory package (e.g. memory package 200 or memory package 300). Optimizing the loads in the memory package can include optimizing the load on one or more conduits and/or drivers. As previously described with respect to FIGS. 2 and 3, the memory package can include a plurality of array dies, a plurality of die interconnects, and a control die. Furthermore, the control die can include a plurality of drivers, each of which may be configured to drive a signal along a die interconnect.

In some implementations, the process 500 can comprise selecting a first subset of array dies and a second subset of array dies from a plurality of array dies (e.g., array dies 310), as shown in operational block 502. Generally, the first subset of array dies and the second subset of array dies may be exclusive of one another. Thus, the first subset of array dies does not include any array dies from the second subset of array dies and vice versa. However, in some cases there may be some overlap between the first subset of array dies and the second subset of array dies. Further, in some cases, at least one of the subsets of array dies includes more than one array die. For instance, the first subset of array dies may include two array dies, and the second subset of array dies may include one array die, which, depending on the embodiment, may or may not be included in the first subset of array dies.

Further, the first subset of array dies and the second subset of array dies may be selected to balance a load on a first driver and a load on a second driver based, at least in part, on the loads of the array dies 310 and on the loads of the die interconnect segments from a first and a second die interconnect. The first die interconnect may be in electrical communication with the first driver and the second die interconnect may be in electrical communication with the second driver. In some embodiments, the first subset of array dies and the second subset of array dies are selected to balance a load on a first conduit and a load on a second conduit. The load on each driver and/or conduit may be calculated using formula (1) as previously described above. In some embodiments, the first subset of array dies and the second subset of array dies may be selected to balance a load on a first driver and a load on a second driver based, at least in part, on the loads of the array dies 310 without considering the loads of the die interconnect segments from the first die interconnect and the second die interconnect.

The process 500 further comprises forming electrical connections between the first die interconnect and the first subset of array dies in an operational block 504. The process 500 further comprises forming electrical connections between the second die interconnect and the second subset of array dies in an operational block 506. Forming the electrical connections places the die interconnects in electrical communication with the respective subsets of array dies. In some embodiments, forming the electrical connections can comprise forming electrical connections between the die interconnects and at least one port from each array die of the respective subsets of array dies.

The process 500 further comprises selecting a driver size for a first driver at block 508 and selecting a driver size for a second driver at block 510. Selecting the driver size can be based, at least in part, on the calculated load on the driver. Generally, the greater the load on the driver, the larger the driver is selected to drive a signal along, for example, a die interconnect. The size of the driver may be adjusted by the selection of the transistor size and/or number of transistors included in the driver. A larger driver often consumes more power than a smaller driver. Thus, in certain embodiments, balancing the loads on the drivers to reduce the load on each driver can reduce the power consumption of a memory package.

In some embodiments, the size of the first driver and the size of the second driver are both less than the size sufficient for a driver to drive a signal along a die interconnect to each of the array dies 310 (e.g., with less than a predetermined or threshold signal degradation). The threshold signal degradation can be based on any one or more characteristics of a signal. For example, the threshold signal degradation can be based on the amplitude of the signal, the frequency of the signal, the noise distortion included in or introduced into the signal, or the shape of the signal, to name a few.

The process 500 further comprises forming electrical connections between the first die interconnect and the first driver in an operational block 512. Similarly, the process 500 further comprises forming electrical connections between the second die interconnect and the second driver in an operational block 514. Forming the electrical connections places the die interconnects in electrical communication with the respective drivers. In some embodiments, forming the electrical connections can comprise forming electrical connections between the die interconnects and a data conduit that includes the respective driver.

Advantageously, certain embodiments of the present disclosure reduce the load on each conduit and on each corresponding driver. In certain embodiments, reducing the load on a driver may increase the speed of data transfer between the array dies and other components in a computer system (e.g. a MCH or a processor). Further, reducing the load on a driver may result in reduced power consumption by the driver and consequently, by the memory package. In addition, certain embodiments of the present disclosure may minimize current switching noise.

Operational Modes

A proposed three-dimensional stacking (3DS) standard for dual in-line memory modules (DIMMs) being considered by the Joint Electron Devices Engineering Council (JEDEC) addresses three major shortcomings in the current JEDEC registered DIMM (RDIMM) and JEDEC load reduced DIMM (LRDIMM) standards (an example LRDIMM structure 600 is schematically illustrated in FIG. 6A). These shortcomings include: a) The DIMM density limitation due to the fixed number of chip-select signals received by the DIMM from the system memory controller; b) The performance loss due to the increased load on the data bus as the DIMM density (e.g., the number of DRAM devices and number of ranks) increases; and c) The upper bound of the DIMM density due to the physical DIMM form factor.

Further, the LRDIMM structure 600 may have timing issues due to signals passing through a single memory buffer 601. In addition, the increased size of the data path of the LRDIMM architecture 600, compared to the HCDIMM architecture 602, an example of which is schematically illustrated in FIG. 6B, may result in more latency and signal integrity issues.

FIG. 7 schematically illustrates an example memory module 700 that has previously been proposed for the 3DS-DIMM standard. The proposed 3DS Dual In-line Memory Module (3DS-DIMM) schematically illustrated in FIG. 7 attempts to address the above shortcomings using two components, a 3DS register 712 and a controller die 722. In some implementations, the 3DS-DIMM 700 includes the 3DS register 712 (also known as an enhanced DDR3 register). The 3DS register 712 may include a DDR3 JEDEC standard register with a “rank multiplication” circuit, which increases the number of the output chip-select signals for selecting an array die 710 by decoding one or more higher-order row or column address bits with the incoming chip-select signals from the system controller. The 3DS Register 712 can also include a command/address buffer, a register operational code buffer (RC word buffer), and rank multiplication logic (e.g., supporting rank multiplication of 1-to-2, 1-to-4, and/or 1-to-8). The 3DS register addresses shortcoming (a) of the JEDEC RDIMM and LRDIMM listed above.

Another component of the proposed 3DS-DIMM is a 3DS dynamic random-access memory (DRAM) package 720. The 3DS DRAM package 720 includes a plurality of stacked DDR DRAM chips 724 or array dies. The 3DS DRAM package 720 has a data I/O load that is equivalent to the data I/O load of a single-die DRAM package, regardless of the actual number of DRAM dies in the 3DS DRAM package 720. The 3DS DRAM package 720 may comprise a plurality of array dies (e.g., 2, 4 or 8 DDR DRAM dies) and a controller die 722. The controller die 722 may include data buffers, a data path timing controller, a secondary command/address buffer, a programmable secondary 1-to-2 rank decoder, and a data path signal (e.g., ODT, ODT, RTT) controller. Examples of such memory packages include HMC. The 3DS DRAM package 720 addresses the shortcomings (b) and (c) of the JEDEC RDIMM and LRDIMM listed above. However, there are deficiencies in the proposed 3DS-DIMM standard as described below.

The JEDEC DDR3 RDIMM standard contains two major components: a DDR3 register and a plurality of DRAM packages each comprising one or more DRAM chips or dies. The DDR3 register serves as a command/address signal buffer and as a command/control decoder. This DDR3 register holds a set of register control (RC) words, which a computer system configures to ensure the proper operation of the RDIMM. The DDR3 register contains a phase-lock-loop (PLL), which functions as a clock synchronizer for each RDIMM. The DDR3 register outputs a set of buffered command/address signals to all the DRAM packages on the RDIMM, but the data signals are directly fed to the DRAM packages from the system memory controller.

In contrast to the JEDEC DDR3 RDIMM standard, the 3DS-DIMM proposal requires the DRAM package 720 to include the controller die 722 that controls all data paths timing and operations. This arrangement of the DRAM package reduces the load on the data bus, however, it presents three significant shortcomings: 1) The command/address buffer in the 3DS DRAM package introduces clock cycle latency since it needs to provide clock synchronous operation to the DRAM dies in the package; 2) The data path control circuit (e.g., ODT, read/write data direction) in the control die becomes very complicated to support semi-synchronous (fly-by) data path control among all 3DS DRAM packages that are on a DIMM; and 3) The variations in the DRAM die timing characteristics within each 3DS DRAM package would be likely to require resynchronization of the data signals during the read/write operations, which increases the read/write latency and the read-to-write and write-to-read turn around time.

The 3DS-DIMM proposal can also be compared to the HyperCloud™ (HC) DIMM architecture of Netlist, Inc. An example of the HCDIMM architecture 602 is illustrated in FIG. 68. Further details and embodiments of the HCDIMM architecture is disclosed in U.S. Pat. Nos. 7,289,386, 7,532,537, 7,619,912, and 7,636,274, each of which is incorporated in its entirety by reference herein. One of the main topological differences between the 3DS-DIMM and HCDIMM architectures is that while the 3DS-DIMM architecture uses a control die 722 to buffer the data signals and to decode command/address signals from the 3DS register, certain configurations of the HCDIMM architecture include a plurality of isolation devices (ID), each of which includes data buffers, but no decoding capability. Unlike the HCDIMM architecture, since the command/address signal needs to pass through the control die 722 in the 3DS DRAM package 720, the 3DS-DIMM proposal presents the same shortcoming (b) of the controller die described above. The data path control signals are generated by the register device (RD) 612 in the HCDIMM architecture 602, while the data path control signals are generated by the control die 722 in the 3DS DRAM. This aspect of the 3DS-DIMM architecture creates timing critical control paths in 3DS-DIMM architecture.

In certain embodiments described herein, a memory module architecture is proposed that includes a set of device components that support JEDEC 3DS operation with the benefit of RDIMM and HCDIMM architectures (see, e.g.,