42. This example is merely illustrative and, in general, antennas 42 may be fed using any desired antenna feeding scheme. If desired, antenna 42 may have multiple antenna feeds that are coupled to one or more radio-frequency transmission line paths 36.

Radio-frequency transmission line path 36 may include transmission lines that are used to route radio-frequency antenna signals within device 10 (FIG. 1). Transmission lines in device 10 may include coaxial cables, microstrip transmission lines, stripline transmission lines, edge-coupled microstrip transmission lines, edge-coupled stripline transmission lines, transmission lines formed from combinations of transmission lines of these types, etc. Transmission lines in device 10 such as transmission lines in radio-frequency transmission line path 36 may be integrated into rigid and/or flexible printed circuit boards.

In performing wireless transmission, processor 26 may provide transmit signals (e.g., digital or baseband signals) to transceiver 28 over path 34. Transceiver 28 may further include circuitry for converting the transmit (baseband) signals received from processor 26 into corresponding radio-frequency signals. For example, transceiver circuitry 28 may include mixer circuitry 54 for up-converting (or modulating) the transmit (baseband) signals to radio frequencies prior to transmission over antenna 42. The example of FIG. 2 in which processor 26 communicates with transceiver 28 is merely illustrative. In general, transceiver 28 may communicate with a baseband processor, an application processor, general purpose processor, a microcontroller, a microprocessor, or one or more processors within circuitry 18. Transceiver circuitry 28 may also include digital-to-analog converter (DAC) and/or analog-to-digital converter (ADC) circuitry for converting signals between digital and analog domains. Transceiver 28 may use transmitter (TX) 30 to transmit the radio-frequency signals over antenna 42 via radio-frequency transmission line path 36 and front end module 40. Antenna 42 may transmit the radio-frequency signals to external wireless equipment by radiating the radio-frequency signals into free space.

In performing wireless reception, antenna 42 may receive radio-frequency signals from the external wireless equipment. The received radio-frequency signals may be conveyed to transceiver 28 via radio-frequency transmission line path 36 and front end module 40. Transceiver 28 may include circuitry such as receiver (RX) 32 for receiving signals from front end module 40 and for converting the received radio-frequency signals into corresponding baseband signals. For example, transceiver 28 may include mixer circuitry 54 for down-converting (or demodulating) the received radio-frequency signals to baseband frequencies prior to conveying the received signals to processor 26 over path 34.

Front end module (FEM) 40 may include radio-frequency front end circuitry that operates on the radio-frequency signals conveyed (transmitted and/or received) over radio-frequency transmission line path 36. FEM 40 may, for example, include front end module (FEM) components such as radio-frequency filter circuitry 44 (e.g., low pass filters, high pass filters, notch filters, band pass filters, multiplexing circuitry, duplexer circuitry, diplexer circuitry, triplexer circuitry, etc.), switching circuitry 46 (e.g., one or more radio-frequency switches), radio-frequency amplifier circuitry 48 (e.g., one or more power amplifier circuits 50 and/or one or more low-noise amplifier circuits 52), impedance matching circuitry (e.g., circuitry that helps to match the impedance of antenna 42 to the impedance of radio-frequency transmission line 36), antenna tuning circuitry (e.g., networks of capacitors, resistors, inductors, and/or switches that adjust the frequency response of antenna 42), radio-frequency coupler circuitry, charge pump circuitry, power management circuitry, digital control and interface circuitry, and/or any other desired circuitry that operates on the radio-frequency signals transmitted and/or received by antenna 42. Each of the front end module components may be mounted to a common (shared) substrate such as a rigid printed circuit board substrate or flexible printed circuit substrate. If desired, the various front end module components may also be integrated into a single integrated circuit chip. If desired, amplifier circuitry 48 and/or other components in front end 40 such as filter circuitry 44 may also be implemented as part of transceiver circuitry 28.

Filter circuitry 44, switching circuitry 46, amplifier circuitry 48, and other circuitry may be disposed along radio-frequency transmission line path 36, may be incorporated into FEM 40, and/or may be incorporated into antenna 42 (e.g., to support antenna tuning, to support operation in desired frequency bands, etc.). These components, sometimes referred to herein as antenna tuning components, may be adjusted (e.g., using control circuitry 14) to adjust the frequency response and wireless performance of antenna 42 over time.

Transceiver 28 may be separate from front end module 40. For example, transceiver 28 may be formed on another substrate such as the main logic board of device 10, a rigid printed circuit board, or flexible printed circuit that is not a part of front end module 40. While control circuitry 14 is shown separately from wireless circuitry 24 in the example of FIG. 1 for the sake of clarity, wireless circuitry 24 may include processing circuitry that forms a part of processing circuitry 18 and/or storage circuitry that forms a part of storage circuitry 16 of control circuitry 14 (e.g., portions of control circuitry 14 may be implemented on wireless circuitry 24). As an example, processor 26 and/or portions of transceiver 28 (e.g., a host processor on transceiver 28) may form a part of control circuitry 14. Control circuitry 14 (e.g., portions of control circuitry 14 formed on processor 26, portions of control circuitry 14 formed on transceiver 28, and/or portions of control circuitry 14 that are separate from wireless circuitry 24) may provide control signals (e.g., over one or more control paths in device 10) that control the operation of front end module 40.

Transceiver circuitry 28 may include wireless local area network transceiver circuitry that handles WLAN communications bands (e.g., Wi-Fi® (IEEE 802.11) or other WLAN communications bands) such as a 2.4 GHz WLAN band (e.g., from 2400 to 2480 MHz), a 5 GHz WLAN band (e.g., from 5180 to 5825 MHz), a Wi-Fi® 6E band (e.g., from 5925-7125 MHz), and/or other Wi-Fi® bands (e.g., from 1875-5160 MHz), wireless personal area network transceiver circuitry that handles the 2.4 GHz Bluetooth® band or other WPAN communications bands, cellular telephone transceiver circuitry that handles cellular telephone bands (e.g., bands from about 600 MHz to about 5 GHz, 3G bands, 4G LTE bands, 5G New Radio Frequency Range 1 (FR1) bands below 10 GHz, 5G New Radio Frequency Range 2 (FR2) bands between 20 and 60 GHz, etc.), near-field communications (NFC) transceiver circuitry that handles near-field communications bands (e.g., at 13.56 MHz), satellite navigation receiver circuitry that handles satellite navigation bands (e.g., a GPS band from 1565 to 1610 MHz, a Global Navigation Satellite System (GLONASS) band, a BeiDou Navigation Satellite System (BDS) band, etc.), ultra-wideband (UWB) transceiver circuitry that handles communications using the IEEE 802.15.4 protocol and/or other ultra-wideband communications protocols, and/or any other desired radio-frequency transceiver circuitry for covering any other desired communications bands of interest.

Wireless circuitry 24 may include one or more antennas such as antenna 42. Antenna 42 may be formed using any desired antenna structures. For example, antenna 42 may be an antenna with a resonating element that is formed from loop antenna structures, patch antenna structures, inverted-F antenna structures, slot antenna structures, planar inverted-F antenna structures, helical antenna structures, monopole antennas, dipoles, hybrids of these designs, etc. Two or more antennas 42 may be arranged into one or more phased antenna arrays (e.g., for conveying radio-frequency signals at millimeter wave frequencies). Parasitic elements may be included in antenna 42 to adjust antenna performance. Antenna 42 may be provided with a conductive cavity that backs the antenna resonating element of antenna 42 (e.g., antenna 42 may be a cavity-backed antenna such as a cavity-backed slot antenna).

It can be challenging to design a radio-frequency transmission line path 36. For instance, consider a scenario in which a radio-frequency amplifier has an output port that is coupled to an additional radio-frequency circuit component such as an antenna or another amplifier. A differential transmission line can be used to couple the radio-frequency amplifier to the additional radio-frequency circuit. To provide impedance matching, one or more transformers can be disposed in the radio-frequency transmission line path. For instance, a transformer can be coupled between the output port of the radio-frequency amplifier and the differential transmission line to provide proper impedance matching between the amplifier and the transmission line. The use of a transformer for impedance matching, however, takes up a significant amount of circuit area while introducing some matching (power) loss. Moreover, the use of a differential transmission line for signal routing can also introduce line (power) loss.

In accordance with an embodiment, differential coupled lines can be used to provide both impedance matching and routing functions. The dual purpose of differential coupled lines can obviate the use of impedance matching transformers in a radio-frequency signal path, which can help substantially reduce chip area while minimizing matching/power loss in the radio-frequency signal path. FIG. 3 is a diagram of an illustrative radio-frequency signal path that includes an amplifier 60 coupled to a set of differential coupled lines 70. As shown in FIG. 3, amplifier 60 may have a differential input port coupled to a transformer such as transformer 62 and may have a differential output port coupled to a set of differential coupled lines 70. Amplifier 60 may generally represent a radio-frequency (RF) amplifier such as a power amplifier 50 in a transmit path, a low-noise amplifier 52 in a receive path, and/or other amplifiers within front end module 40 or transceiver circuitry 28. Transformer 62 may include a primary coil (winding) 64 and a secondary coil (winding) 66 coupled to the input port of amplifier 60. Transformer 62 may be used to receive a radio-frequency signal from another circuit within front end module 40 or transceiver 28 and is sometimes referred to as an input coupling transformer 62.

The set of differential coupled lines 70 may be directly coupled (connected) to the differential output port of amplifier 60. Lines 70 may include a first pair of coupled lines 72-1a and 72-1b and a second pair of coupled lines 72-2a and 72-2b. The term “coupled lines” can be referred to and defined herein as at least two elongated conductive lines that are capacitive and magnetically coupled to one another. Line 72-1a may be a conductive routing path having a first terminal (a first distal end) coupled to a first output terminal of amplifier 60 and having a second terminal (a second distal end) coupled to a bias voltage line 76. Bias voltage line 76 may receive a positive power supply voltage or some other bias voltage less than or greater than the positive power supply voltage. Line 72-1b may be a conductive routing path having a first terminal (a first distal end) coupled to a ground line 74 (e.g., a ground power supply line on which a ground voltage is provided) and having a second terminal (a second distal end) coupled to output port 78.

Lines 72-1a and 72-1b may be routed parallel to each another. Although drawn as straight lines in the example of FIG. 3, lines 72-1a and 72-1b need not be completely straight and can have one or more turns, can be curved, can be routed vertically and/or horizontally across the surface of an integrated circuit chip, and/or can form a routing path with any desired shape. Lines 72-1a and 72-1b can have the same footprint. Line 72-1b should generally be routed along or follow line 72-1a and therefore has the same or similar length as line 72-1a. The amount of capacitive and magnetic coupling between lines 72-1a and 72-1b should be designed by selecting the spacing between them to satisfy the required impedance transformation between the preceding and succeeding circuitry. Lines 72-1a and 72-1b can be fairly long. As examples, lines 72-1a and 72-1b can each be at least 50 microns in length, 50-100 microns in length, 100-200 microns in length, 200-400 microns in length, or more than 400 microns long. Conductive lines 72-1a and 72-1b that are routed close to and alongside each other are sometimes referred to collectively and defined as “coupled lines” or a pair of coupled lines that are capacitively and magnetically coupled to one another.

Coupled lines 72-1a and 72-1b may be formed laterally next to each other (as shown in the cross-sectional side view of FIG. 5) or may be formed vertically on top of one another (as shown in the cross-sectional side view of FIG. 6). FIG. 5 illustrates coupled lines 72a and 72b both formed on a semiconductor substrate 84 and cover be dielectric (insulating) material 86. This arrangement in which coupled lines 72a and 72b are formed in the same plane is sometimes referred to as an edge-coupled microstrip configuration. This is illustrative. If desired, the edge-coupled lines can also be implemented as edge-coupled coplanar waveguides, edge-coupled coplanar waveguides with ground, and edge-coupled grounded coplanar waveguides.

FIG. 6 illustrates another arrangement in which line 72b is stacked on top of line 72a (or vice versa). As shown in FIG. 6, line 72a is formed on substrate 84, whereas line 72b is disposed over line 72a within dielectric (insulating) material 86. The example of FIG. 6 in which line 72b is horizontally aligned with line 72a (e.g., line 72b completely overlaps and covers line 72a from above) is illustrative. If desired, line 72b can be partially offset from line 72a such that line 72b only partially overlaps or covers line 72a from above. The arrangement in which coupled lines 72a and 72b are formed in different planes over substrate 84 is sometimes referred to as a broadside-coupled microstrip configuration. If desired, other types of coupled stripline or microstrip line arrangements can be employed.

Line 72-2a may be a conductive routing path having a first terminal (a first distal end) coupled to a second output terminal of amplifier 60 and having a second terminal (a second distal end) coupled to bias voltage line 76. The first and second output terminals of amplifier 60 collectively form the differential output port of amplifier 60. Line 72-2b may be a conductive routing path having a first terminal (a first distal end) coupled to ground line 74 and having a second terminal (a second distal end) coupled to output port 78. Output port 78 (e.g., a differential interface) may be coupled to an interface to another integrated circuit chip, an antenna, or some other load component.

Lines 72-2a and 72-2b may be routed parallel to each another. Although drawn as straight lines in the example of FIG. 3, lines 72-2a and 72-2b need not be completely straight and can have one or more turns, can be curved, can be routed vertically and/or horizontally across the surface of an integrated circuit chip, and/or can form a routing path with any desired shape. Lines 72-2a and 72-2b can have the same footprint. Line 72-2b should generally be routed along or follow line 72-2a and therefore has the same or similar length as line 72-2a. The amount of capacitive and magnetic coupling between lines 72-2a and 72-2b should be designed by selecting the spacing between them to satisfy the required impedance transformation requirement between the precedent and subsequent circuitry.

Lines 72-2a and 72-2b can be fairly long. As examples, lines 72-2a and 72-2b can each be at least 50 microns in length, 50-100 microns in length, 100-200 microns in length, 200-400 microns in length, or more than 400 microns long. Conductive lines 72-2a and 72-2b that are routed close to and alongside each other are sometimes referred to collectively and defined as “coupled lines” or a pair of coupled lines that are capacitively and magnetically coupled to one another. Coupled lines 72-2a and 72-2b may be edge-coupled strip lines (see, e.g., FIG. 5), broadside-coupled strip lines (see, e.g., FIG. 6), coplanar waveguides, coplanar waveguides with ground, grounded coplanar waveguides, or other types of coupled lines. To maintain proper balance of a differential signal being routed through differential coupled lines 70, the first pair of coupled lines 72-1a and 72-1b and the second pair of coupled lines 72-2a and 72-2b should generally be routed in the same way in the same direction (e.g., in a symmetrical manner).

As described above, the first pair of coupled lines 72-1a and 72-1b and the second pair of coupled lines 72-2a and 72-2b can be referred to collectively and defined as differential coupled lines 70. Differential coupled lines 70 can not only be used to provide routing but can also be used to provide impedance matching. For example, consider a scenario in which output port 78 is connected to a 100 Ohm load. In such scenario, differential coupled lines 70 can be designed and configured (e.g., by selecting the length, width, shape, footprint, and other physical characteristics of the coupled lines) to match the impedance of the output port of amplifier 60 to the 100 Ohm load. Using only differential coupled lines 70 to provide an impedance matching function obviates the need for a separate output transformer, which can dramatically reduce circuit area that would otherwise be occupied by the output transformer while also minimizing matching/power loss through the radio-frequency signal path. This example of using differential coupled lines 70 to match to a 100 Ohm load is illustrative. In general, differential coupled lines 70 can be used to provide impedance matching to a 50 Ohm load, to a 75 Ohm load, to a 25 Ohm load, other resistive loads, or other types of output components.

The example of FIG. 4 in which amplifier 60 has a differential input port coupled to a transformer 62 and a differential output port coupled to differential coupled lines 70 is illustrative. FIG. 4 illustrates another embodiment in which amplifier 60 has a differential input port coupled to differential transmission lines 80 and 82 and a differential output port coupled to differential coupled lines 70. As shown in FIG. 4, amplifier 60 has a first input terminal coupled to conductive line 80 and has a second input terminal coupled to conductive line 82. Conductive lines 80 and 82 may collectively form a differential transmission line path. In other words, amplifier 60 can have an input configured to receive radio-frequency signals via a transformer (as shown in the embodiment of FIG. 3) or via a differential transmission line path (as shown in the embodiment of FIG. 4).

FIG. 7 shows another embodiment in which a set of differential coupled lines can be used to provide impedance matching between two different amplifiers. As shown in FIG. 7, differential coupled lines 70 can be coupled between a first amplifier 60-1 (sometimes referred to as a first amplifier stage) and a second amplifier 60-2 (sometimes referred to as a second amplifier stage). Both amplifier stages 60-1 and 60-2 can be differential radio-frequency amplifiers. Differential coupled lines 70 may include a first pair of coupled lines 72-1a and 72-1b and a second pair of coupled lines 72-2a and 72-2b.

Line 72-1a may be a conductive routing path having a first terminal (a first distal end) coupled to a first output terminal of amplifier 60-1 via an optional series transmission line 90-1 and having a second terminal (a second distal end) coupled to bias voltage line 76. Bias voltage line 76 may receive a positive power supply voltage or some other bias voltage less than or greater than the positive power supply voltage. Line 72-1b may be a conductive routing path having a first terminal (a first distal end) coupled to ground line 74 and having a second terminal (a second distal end) coupled to a first input terminal of amplifier 60-2 via an optional series transmission line 92-1.

Lines 72-1a and 72-1b may be routed parallel to each another. Although drawn as straight lines in the example of FIG. 7, lines 72-1a and 72-1b need not be completely straight and can have one or more turns, can be curved, can be routed vertically and/or horizontally across the surface of an integrated circuit chip, and/or can form a routing path with any desired shape. Lines 72-1a and 72-1b can have the same footprint. Line 72-1b should generally be routed along or follow line 72-1a and therefore has the same or similar length as line 72-1a. The amount of capacitive coupling between lines 72-1a and 72-1b can be maximized by forming them close to each other. By strongly coupling lines 72-1a and 72-1b to each other, the pair of coupled lines are weakly coupled to neighboring passive components. Lines 72-1a and 72-1b can be fairly long. As examples, lines 72-1a and 72-1b can each be at least 50 microns in length, 50-100 microns in length, 100-200 microns in length, 200-400 microns in length, or more than 400 microns long. Conductive lines 72-1a and 72-1b that are routed close to and alongside each other are sometimes referred to collectively and defined as “coupled lines” or a pair of coupled lines.

Line 72-2a may be a conductive routing path having a first terminal (a first distal end) coupled to a second output terminal of amplifier 60-1 via an optional series transmission line 90-2 and having a second terminal (a second distal end) coupled to bias voltage line 76. The first and second output terminals of amplifier 60-1 may serve collectively as the differential output port of amplifier 60-1. Line 72-2b may be a conductive routing path having a first terminal (a first distal end) coupled to ground line 74 and having a second terminal (a second distal end) coupled to a second input terminal of amplifier 60-2 via an optional series transmission line 92-2. The first and second input terminals of amplifier 60-2 may serve collectively as the differential input port of amplifier 60-2.

Lines 72-2a and 72-2b may be routed parallel to each another. Although drawn as straight lines in the example of FIG. 7, lines 72-2a and 72-2b need not be completely straight and can have one or more turns, can be curved, can be routed vertically and/or horizontally across the surface of an integrated circuit chip, and/or can form a routing path with any desired shape. Lines 72-2a and 72-2b can have the same footprint. Line 72-2b should generally be routed along or follow line 72-2a and therefore has the same or similar length as line 72-2a. The amount of capacitive coupling between lines 72-2a and 72-2b can be maximized by forming them close to each other. By strongly coupling lines 72-2a and 72-2b to each other, the pair of coupled lines are weakly coupled to neighboring passive components. Lines 72-2a and 72-2b can be fairly long. As examples, lines 72-2a and 72-2b can each be at least 50 microns in length, 50-100 microns in length, 100-200 microns in length, 200-400 microns in length, or more than 400 microns long. Conductive lines 72-2a and 72-2b that are routed close to and alongside each other are sometimes referred to collectively and defined as “coupled lines” or a pair of coupled lines.

Series transmission lines 90-1 and 90-2 (sometimes referred to collectively as a differential transmission line 90) coupled between the output of first amplifier 60-1 and differential coupled lines 70 is optional (e.g., differential line 90 can be omitted). Differential line 90 may be shorter or longer than differential coupled lines 70. Similarly, transmission lines 92-1 and 92-2 coupled between differential coupled line 70 and the input of second amplifier 60-2 is optional (e.g., differential transmission line 92 can be omitted, if desired). Differential line 92 may be shorter or longer than differential coupled lines 70.

In the example of FIG. 7, differential transmission lines 90 can be coupled between the first amplifier stage and differential coupled lines 70, whereas differential transmission lines 92 can be coupled between the differential coupled lines 70 and the second amplifier stage. As another example, the first amplifier stage can be directly connected to differential coupled lines 70 (e.g., lines 90-1 and 90-2 are omitted), whereas differential transmission lines 92 can be coupled between the differential coupled lines 70 and the second amplifier stage. As another example, differential transmission lines 90 can be coupled between the first amplifier stage and differential coupled lines 70, whereas differential coupled lines 70 can be directly connected to the second amplifier stage (e.g., lines 92-1 and 92-2 are omitted). As yet another example, the first amplifier stage can be directly connected to differential coupled lines 70 (e.g., lines 90-1 and 90-2 are omitted), differential coupled lines 70 can be directly connected to the second amplifier stage (e.g., lines 92-1 and 92-2 are also omitted).

In these various combinations, the differential coupled lines 70 and/or the series transmission lines 90/92 (if used) can be designed and configured (e.g., by selecting the length, width, shape, footprint, and other physical characteristics of these conductive paths) to provide the requisite routing and proper impedance matching between the two amplifiers 60-1 and 60-2 to ensure minimal power/signal loss. Using only differential coupled lines 70 and optionally differential lines 90 and 92 to provide both routing and matching functions obviates the need for matching transformers, which can dramatically reduce circuit area that would otherwise be occupied by the matching transformers while also providing improved flexibility for connecting amplifier 60-1 to amplifier 60-2, the locations of which are sometimes dictated by strict floorplan constraints.

FIG. 8 is a Smith chart illustrating how differential lines 90, 70, and 92 of the type shown in FIG. 7 can be configured to provide interstage matching for amplifiers 60-1 and 60-2. In FIG. 8, point 100 may represent the impedance at the output port of the first amplifier stage 60-1. Differential lines 90 may, for example, transform the impedance at the output port of the first amplifier stage from point