Noise reduction for envelope tracking

Patent metadata

Field	Value
Publication number	US-9298198-B2
Application number	US-201213727911-A
Country	US
Kind code	B2
Filing date	Dec 27, 2012
Priority date	Dec 28, 2011
Publication date	Mar 29, 2016
Grant date	Mar 29, 2016

Abstract

A direct current (DC)-DC converter, which includes a parallel amplifier, a radio frequency (RF) trap, and a switching supply, is disclosed. The switching supply includes switching circuitry and a first inductive element. The parallel amplifier has a feedback input and a parallel amplifier output. The switching circuitry has a switching circuitry output. The first inductive element is coupled between the switching circuitry output and the feedback input. The RF trap is coupled between the parallel amplifier output and a ground.

First claim

What is claimed is:

1. Circuitry comprising:
a parallel amplifier having a feedback input and a parallel amplifier output;
a radio frequency (RF) trap coupled between the parallel amplifier output and a ground;
a switching supply comprising:
switching circuitry having a switching circuitry output; and
a first inductive element coupled between the switching circuitry output and the feedback input; and

a direct current (DC) power source adapted to provide a DC source signal to the parallel amplifier and the switching supply.

2. The circuitry of claim 1 wherein the parallel amplifier output is directly coupled to the feedback input.

3. The circuitry of claim 1 wherein the RF trap comprises a trap capacitive element and a trap inductive element coupled in series.

4. The circuitry of claim 1 wherein the RF trap comprises a trap capacitive element, a trap inductive element, and a trap resistive element coupled in series.

5. The circuitry of claim 1 further comprising an offset capacitive element coupled between the parallel amplifier output and the feedback input, such that the parallel amplifier is 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.

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

7. The circuitry of claim 1 wherein:
the parallel amplifier is adapted to partially provide a first power supply output signal via the parallel amplifier output based on a voltage setpoint; and
the switching supply is adapted to partially provide the first power supply output signal via the first inductive element.

8. The circuitry of claim 7 wherein the RF trap has a frequency response with an RF notch at an RF notch frequency and is adapted to filter the first power supply output signal based on the frequency response.

9. The circuitry of claim 8 wherein the RF notch frequency is equal to about 30 megahertz.

10. The circuitry of claim 8 wherein the RF notch frequency is about equal to an RF receive frequency.

11. The circuitry of claim 8 further comprising an 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.

12. The circuitry of claim 11 wherein the RF notch frequency is about equal to an RF duplex frequency, which is about equal to a difference between an RF transmit frequency and an RF receive frequency.

13. The circuitry of claim 12 wherein the RF duplex frequency is greater than or equal to about 30 megahertz.

14. The circuitry of claim 11 wherein the first envelope power supply signal provides power for amplification to the RF PA.

15. The circuitry of claim 11 wherein a bandwidth of the first envelope power supply signal is greater than or equal to about 20 megahertz.

16. The circuitry of claim 11 further comprising the RF PA.

17. The circuitry of claim 7 wherein the voltage setpoint is based on a power supply control signal.

18. The circuitry of claim 7 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.

19. The circuitry of claim 7 wherein:
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.

20. The circuitry of claim 19 wherein the DC power source is a battery.

21. The circuitry of claim 19 further comprising the DC power source.

22. The circuitry of claim 1 wherein the switching supply further comprises a second inductive element coupled between the feedback input and the parallel amplifier output.

23. The circuitry of claim 22 wherein:
the parallel amplifier is adapted to partially provide a first power supply output signal via the parallel amplifier output based on a voltage setpoint; and
the switching supply is adapted to partially provide the first power supply output signal via the first inductive element and the second inductive element.

24. The circuitry of claim 23 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.

25. The circuitry of claim 23 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.

26. The circuitry of claim 22 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.

27. The circuitry of claim 22 further comprising an offset capacitive element coupled between the parallel amplifier output and the second inductive element, such that the parallel amplifier is 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.

28. A method comprising:
providing a DC source signal to a parallel amplifier and a switching supply circuitry;
partially providing a first power supply output signal via a first inductive element inside the switching supply circuitry;
partially providing the first power supply output signal via a parallel amplifier output based on a voltage setpoint;
regulating a voltage of the first power supply output signal received at a feedback input of the parallel amplifier; and
filtering the first power supply output signal based on a frequency response of a radio frequency (RF) trap.

Assignees

• Rf Micro Devices Inc

Inventors

• Kay Michael R
• Gorisse Philippe
• Khlat Nadim
• Folkmann Andrew F
• Nag Manbir Singh
• Chiron Jean-Frederic

Classifications

• H03F2200/432

  Two or more amplifiers of different type are coupled in parallel at the input or output, e.g. a class D and a linear amplifier, a class B and a class A amplifier · CPC title

• H02M3/158

  including plural semiconductor devices as final control devices for a single load · CPC title

• H02M2001/0045

  Electricity · mapped topic

• H03F1/0266

  by using a signal derived from the input signal · CPC title

• H03F2200/102

  A non-specified detector of a signal envelope being used in an amplifying circuit · CPC title