Inductance based parallel amplifier phase compensation

1. Circuitry comprising:

a parallel amplifier having a feedback input and a parallel amplifier output; and

a switching supply comprising:

switching circuitry having a switching circuitry output;

a first inductive element coupled between the switching circuitry output and the feedback input; and

a second inductive element coupled between the feedback input and the parallel amplifier output, wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is at least 10 times greater than a magnitude of the second inductance.

2. Circuitry comprising:

a parallel amplifier having a feedback input and a parallel amplifier output, and adapted to partially provide a first power supply output signal via the parallel amplifier output based on a voltage setpoint; and

a switching supply comprising:

switching circuitry having a switching circuitry output;

a first inductive element coupled between the switching circuitry output and the feedback input; and

a second inductive element coupled between the feedback input and the parallel amplifier output, wherein the switching supply is adapted to partially provide the first power supply output signal via the first inductive element and the second inductive element.

3. The circuitry of claim 2 wherein the voltage setpoint is based on a power supply control signal.

4. The circuitry of claim 2 wherein:

the parallel amplifier is further adapted to regulate a voltage of the first power supply output signal based on the voltage setpoint; and

the switching supply is further adapted to regulate the first power supply output signal to minimize an output current from the parallel amplifier.

5. The circuitry of claim 2 wherein a phase-shift across the second inductive element at least partially compensates for limited open loop gain of the parallel amplifier at frequencies above a frequency threshold.

6. The circuitry of claim 2 further comprising a radio frequency (RF) power amplifier (PA), wherein:

the first power supply output signal is a first envelope power supply signal; and

the RF PA is adapted to receive and amplify an RF input signal to provide an RF transmit signal using the first envelope power supply signal.

7. The circuitry of claim 6 wherein the first envelope power supply signal provides power for amplification to the RF PA.

8. The circuitry of claim 6 wherein the RF PA comprises a final stage adapted to provide the RF transmit signal using the first envelope power supply signal.

9. The circuitry of claim 6 wherein:

the first inductive element and the second inductive element are connected to one another at a connection node;

the first inductive element and the second inductive element are adapted to provide a second power supply output signal via the connection node;

the second power supply output signal is a second envelope power supply signal;

the RF PA comprises a driver stage and a final stage, which is coupled to the driver stage;

the driver stage receives and amplifies the RF input signal to provide a driver stage output signal using the second envelope power supply signal; and

the final stage receives and amplifies the driver stage output signal to provide the RF transmit signal using the first envelope power supply signal.

10. The circuitry of claim 2 wherein:

a DC power source is adapted to provide a DC source signal to the parallel amplifier and to the switching supply;

the parallel amplifier is further adapted to partially provide the first power supply output signal using the DC source signal; and

the switching supply is further adapted to partially provide the first power supply output signal using the DC source signal.

11. The circuitry of claim 10 wherein the DC power source is a battery.

12. The circuitry of claim 10 further comprising the DC power source.

13. The circuitry of claim 2 wherein:

the first inductive element and the second inductive element are connected to one another at a connection node; and

the first inductive element and the second inductive element are adapted to provide a second power supply output signal via the connection node.

14. The circuitry of claim 1 wherein the switching supply further comprises an offset capacitive element coupled between the parallel amplifier output and the second inductive element, such that the parallel amplifier is further adapted to partially provide a first power supply output signal via the parallel amplifier output and the offset capacitive element based on a voltage setpoint.

15. The circuitry of claim 1 wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is at least 100 times greater than a magnitude of the second inductance.

16. The circuitry of claim 1 wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is at least 500 times greater than a magnitude of the second inductance.

17. The circuitry of claim 1 wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is at least 1000 times greater than a magnitude of the second inductance.

18. The circuitry of claim 1 wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is less than 1000 times greater than a magnitude of the second inductance.

19. The circuitry of claim 1 wherein the first inductive element has a first inductance and the second inductive element has a second inductance, such that a magnitude of the first inductance is less than 5000 times greater than a magnitude of the second inductance.

20. The circuitry of claim 1 wherein the switching supply further comprises a filter capacitive element coupled between the parallel amplifier output and a ground.

21. Circuitry comprising:

a parallel amplifier having a feedback input and a parallel amplifier output; and

a switching supply comprising:

switching circuitry having a switching circuitry output;

a first inductive element coupled between the switching circuitry output and the feedback input; and

a second inductive element coupled between the feedback input and the parallel amplifier output, wherein:

the switching supply further comprises a filter capacitive element coupled between the parallel amplifier output and a ground;

the first inductive element, the second inductive element, and the filter capacitive element form a first low-pass filter having a first cutoff frequency; and

the second inductive element, and the filter capacitive element form a second low-pass filter having a second cutoff frequency.

22. The circuitry of claim 21 wherein the second cutoff frequency is at least 10 times greater than the first cutoff frequency.

23. The circuitry of claim 21 wherein the second cutoff frequency is at least 100 times greater than the first cutoff frequency.

24. The circuitry of claim 21 wherein the second cutoff frequency is at least 500 times greater than the first cutoff frequency.

25. The circuitry of claim 21 wherein the second cutoff frequency is at least 1000 times greater than the first cutoff frequency.

26. The circuitry of claim 21 wherein the second cutoff frequency is less than 1000 times greater than the first cutoff frequency.

27. The circuitry of claim 21 wherein the second cutoff frequency is less than 5000 times greater than the first cutoff frequency.