Using a switching signal delay to reduce noise from a switching power supply

• US 9,250,643 B2
• Filed: 11/30/2012
• Issued: 02/02/2016
• Est. Priority Date: 11/30/2011
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Khlat, Nadim
• Primary Examiner(s): Behm, Harry
• Assistant Examiner(s): NOVAK, PETER MICHAEL
• Application Number:
  US13/689,940
• Publication Number:
  US 20130134956A1
• Time in Patent Office: 1,159 Days
• US Class Current: 1/1
• CPC Class Codes: G05F 3/02 Regulating voltage or current
• CPC Class Codes: H02M 1/143 using compensating arrangements for reducing noise from the supply in transmission systems H04B15/005
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/1586 switched with a phase shift, i.e. interleaved

Abstract

Embodiments of circuitry, which includes power supply switching circuitry, a first inductive element, and a second inductive element, are disclosed. The power supply switching circuitry provides a first switching output signal to the first inductive element and a second switching output signal to the second inductive element. The first inductive element has a first inductor current and the second inductive element has a second inductor current. The second switching output signal is delayed from the first switching output signal by a switching signal delay. The first inductor current and the second inductor current combine to provide a combined inductor current, which has a frequency response with a group of notches, such that frequency locations of the group of notches are based on the switching signal delay.

Claims

1. Circuitry comprising:

a power supply output; and

power supply switching circuitry adapted to provide;

a first switching output signal to a first inductive element; and

a second switching output signal to a second inductive element, such that the second switching output signal is delayed from the first switching output signal by a switching signal delay, wherein;

the first inductive element is coupled between the power supply switching circuitry and the power supply output;

the second inductive element is coupled between the power supply switching circuitry and the power supply output;

the first inductive element is adapted to have a first inductor current; and

the second inductive element is adapted to have a second inductor current, such that the first inductor current and the second inductor current combine to provide a combined inductor current, which has a frequency response with a plurality of notches, such that frequency locations of the plurality of notches are based on the switching signal delay.

2. The circuitry of claim 1 wherein a waveshape of the second switching output signal is about equal to a waveshape of the first switching output signal.

3. The circuitry of claim 1 wherein an inductance of the second inductive element is about equal to an inductance of the first inductive element.

4. The circuitry of claim 1 further comprising power supply control circuitry adapted to select the switching signal delay.

5. The circuitry of claim 4 wherein the switching signal delay is selected, such that a frequency of one of the plurality of notches is about equal to a radio frequency (RF) receive frequency.

6. The circuitry of claim 4 wherein the switching signal delay is selected, such that a frequency of one of the plurality of notches is about equal to a radio frequency (RF) duplex frequency, which is about equal to a difference between an RF transmit frequency and an RF receive frequency.

7. The circuitry of claim 6 wherein the RF duplex frequency is greater than or equal to about 50 megahertz.

8. The circuitry of claim 1 further comprising a first capacitive element, such that:

a first power supply has the power supply output, the power supply switching circuitry, the first inductive element, the second inductive element, and the first capacitive element;

the first capacitive element is coupled between the power supply output and a ground; and

the first power supply is adapted to provide a first power supply output signal via the power supply output based on the combined inductor current.

9. The circuitry of claim 8 wherein the first power supply output signal is an envelope power supply signal.

10. The circuitry of claim 9 wherein the envelope power supply signal is amplitude modulated to at least partially provide envelope tracking.

11. The circuitry of claim 10 wherein a bandwidth of the envelope power supply signal is greater than or equal to about 10 megahertz.

12. The circuitry of claim 10 wherein a bandwidth of the envelope power supply signal is greater than or equal to about 20 megahertz.

13. The circuitry of claim 9 wherein an RF power amplifier is adapted to receive and amplify an RF input signal to provide an RF transmit signal using the envelope power supply signal, which provides power for amplification.

14. The circuitry of claim 13 wherein the RF power amplifier is further adapted to operate with approximately constant gain and with gain compression, such that the gain compression is greater than about one decibel.

15. The circuitry of claim 14 wherein the gain compression is equal to about two decibels.

16. The circuitry of claim 14 wherein the gain compression is equal to about three decibels.

17. The circuitry of claim 8 further comprising an analog supply, such that:

the first power supply further comprises a switching supply and the analog supply;

the switching supply comprises the power supply switching circuitry, the first inductive element, the second inductive element, and the first capacitive element;

the switching supply is adapted to at least partially provide the first power supply output signal;

the analog supply is adapted to at least partially provide the first power supply output signal;

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

the switching supply is adapted to drive an output current from the analog supply toward zero.

18. The circuitry of claim 17 wherein:

the analog supply comprises a parallel amplifier;

the parallel amplifier is adapted to at least partially provide the first power supply output signal;

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

the switching supply is further adapted to drive an output current from the parallel amplifier toward zero.

19. The circuitry of claim 18 wherein:

the first power supply further comprises power supply control circuitry adapted to;

select the switching signal delay;

provide a first switching control signal, such that the first switching output signal is based on the first switching control signal; and

provide a second switching control signal, such that the second switching output signal is based on the second switching control signal;

the analog supply further comprises ripple cancellation circuitry;

the ripple cancellation circuitry is adapted to at least partially cancel ripple current from the combined inductor current using the first switching control signal and the second switching control signal; and

the switching supply is further adapted to drive an output current from the ripple cancellation circuitry toward zero.

20. The circuitry of claim 1 wherein the switching signal delay is greater than or equal to about 2 nanoseconds.

21. The circuitry of claim 1 wherein the switching signal delay is less than or equal to about 15 nanoseconds.

22. The circuitry of claim 21 wherein a period of the first switching output signal is greater than about 50 nanoseconds.

23. The circuitry of claim 21 wherein a period of the first switching output signal is greater than about 100 nanoseconds.

24. The circuitry of claim 21 wherein a period of the first switching output signal is greater than about 150 nanoseconds.

25. The circuitry of claim 1 further comprising packaging, which comprises the first inductive element and the second inductive element, such that the first inductive element and the second inductive element are closely matched to one another.

26. Circuitry comprising:

power supply switching circuitry adapted to provide;

a first switching output signal to a first inductive element; and

a second switching output signal to a second inductive element, such that the second switching output signal is delayed from the first switching output signal by a switching signal delay;

the first inductive element adapted to have a first inductor current; and

the second inductive element adapted to have a second inductor current, such that the first inductor current and the second inductor current combine to provide a combined inductor current, which has a frequency response with a plurality of notches, such that frequency locations of the plurality of notches are based on the switching signal delay.

27. A method comprising:

providing a first switching output signal to a first inductive element, which has first inductor current;

providing a second switching output signal to a second inductive element, which has a second inductor current;

delaying the second switching output signal from the first switching output signal by a switching signal delay; and

combining the first inductor current and the second inductor current to provide a combined inductor current, which has a frequency response with a plurality of notches, such that frequency locations of the plurality of notches are based on the switching signal delay.