Reducing effects of RF mixer-based artifact using pre-distortion of an envelope power supply signal

• US 9,197,256 B2
• Filed: 10/08/2013
• Issued: 11/24/2015
• Est. Priority Date: 10/08/2012
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Khlat, Nadim
• Primary Examiner(s): Nguyen, Lee
• Application Number:
  US14/048,109
• Publication Number:
  US 20140099906A1
• Time in Patent Office: 777 Days
• Field of Search: 455/114.3, 375/296
• US Class Current: 1/1
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 1/0266 by using a signal derived from the input signal
• CPC Class Codes: H03F 1/3223 using feed-forward H03F1/3211 takes precedence
• CPC Class Codes: H03F 1/3241 using predistortion circuits H03F1/3211, H03F1/3217 take precedence
• CPC Class Codes: H03F 1/3247 using feedback acting on predistortion circuits H03F1/3264 takes precedence
• CPC Class Codes: H03F 2200/336 A I/Q, i.e. phase quadrature, modulator or demodulator being used in an amplifying circuit
• CPC Class Codes: H03F 3/195 in integrated circuits
• CPC Class Codes: H03F 3/24 of transmitter output stages
• CPC Class Codes: H03F 3/245 with semiconductor devices only
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence
• CPC Class Codes: H04B 2001/0441 with linearisation using feed-forward

Abstract

A radio frequency (RF) power amplifier (PA) and an envelope tracking power supply are disclosed. The RF PA receives and amplifies an RF input signal to provide an RF transmit signal using an envelope power supply signal, which at least partially envelope tracks the RF transmit signal, such that the RF input signal has an RF mixer-based artifact. The envelope tracking power supply provides the envelope power supply signal, which includes mixer-based artifact pre-distortion to at least partially remove effects of the RF mixer-based artifact from the RF transmit signal.

Claims

1. Circuitry comprising:

A radio frequency (RF) power amplifier (PA) configured to receive and amplify an RF input signal to provide an RF transmit signal using an envelope power supply signal, which at least partially envelope tracks the RF transmit signal, wherein the RF input signal has a desired frequency content and an RF mixer-based artifact that includes an image of the desired frequency content; and

an envelope tracking power supply configured to provide the envelope power supply signal, which includes mixer-based artifact pre-distortion to at least partially remove effects of the RF mixer-based artifact from the RF transmit signal.

2. The circuitry of claim 1 wherein a complex RF modulator is configured to provide the RF input signal.

3. The circuitry of claim 2 further comprising the complex RF modulator.

4. The circuitry of claim 2 further comprising RF transmitter circuitry, which comprises the RF PA and the envelope tracking power supply, such that the complex RF modulator is external to the RF transmitter circuitry.

5. The circuitry of claim 1 wherein a complex RF modulator comprises a quadrature RF mixer, such that the RF input signal and the RF mixer-based artifact are both produced by the quadrature RF mixer.

6. The circuitry of claim 5 wherein the RF mixer-based artifact is based on a DC offset of the quadrature RF mixer.

7. The circuitry of claim 1 further comprising an RF communications system, which comprises the RF PA and the envelope tracking power supply.

8. The circuitry of claim 7 wherein the RF communications system is configured to receive an RF receive signal, such that the effects of the RF mixer-based artifact comprise receiver de-sensitization of the RF communications system.

9. The circuitry of claim 8 wherein the RF receive signal and the RF transmit signal are full-duplex RF signals.

10. The circuitry of claim 7 wherein the RF communications system further comprises a complex RF modulator and envelope signal processing circuitry, such that the complex RF modulator comprises a quadrature RF mixer;

the RF input signal and the RF mixer-based artifact are both produced by the quadrature RF mixer; and

the envelope power supply signal is based on the envelope signal processing circuitry.

11. The circuitry of claim 7 wherein the RF input signal and the RF mixer-based artifact are both produced by a quadrature RF mixer, and the envelope power supply signal is based on envelope signal processing circuitry.

12. The circuitry of claim 11 wherein the envelope signal processing circuitry is configured to provide an envelope power supply control signal, such that the envelope power supply signal and the mixer-based artifact pre-distortion are both based on the envelope power supply control signal.

13. The circuitry of claim 12 wherein the envelope signal processing circuitry comprises at least one look-up table (LUT), such that the mixer-based artifact pre-distortion is further based on the at least one LUT.

14. The circuitry of claim 1 wherein the image of the desired frequency content falls within an RF receive channel.

15. The circuitry of claim 1 wherein a harmonic of the image of the desired frequency content falls within an RF receive channel.

16. The circuitry of claim 1 wherein a harmonic of the image of the desired frequency content falls within a non-cellular communications band.

17. Circuitry comprising:

a radio frequency (RF) power amplifier (PA) configured to receive and amplify an RF input signal to provide an RF transmit signal using an envelope power supply signal, which at least partially envelope tracks the RF transmit signal, wherein the RF input signal has a desired frequency content and an RF mixer-based artifact; and

an envelope tracking power supply configured to provide the envelope power supply signal, which includes mixer-based artifact pre-distortion to at least partially remove effects of the RF mixer-based artifact from the RF transmit signal, wherein;

a complex RF modulator comprises a quadrature RF mixer, such that the desired frequency content and the RF mixer-based artifact are both produced by the quadrature RF mixer;

the RF mixer-based artifact comprises intermodulation content produced by the quadrature RF mixer; and

the intermodulation content and a non-linearity of the RF PA combine to provide an image foldover of an image of the desired frequency content of the RF input signal.

18. The circuitry of claim 17 wherein the image foldover falls within an RF receive channel.

19. The circuitry of claim 17 wherein a harmonic of the image foldover falls within an RF receive channel.

20. The circuitry of claim 17 wherein the image foldover falls within a non-cellular communications band.

21. The circuitry of claim 17 wherein a harmonic of the image foldover falls within a non-cellular communications band.

22. The circuitry of claim 21 wherein the non-cellular communications band is a Personal Handy-phone System (PHS) band.

23. Circuitry comprising:

a radio frequency (RF) power amplifier (PA) configured to receive and amplify an RF input signal to provide an RF transmit signal using an envelope power supply signal, which at least partially envelope tracks the RF transmit signal, wherein the RF input signal has a desired frequency content and an RF mixer-based artifact; and

an envelope tracking power supply configured to provide the envelope power supply signal, which includes mixer-based artifact pre-distortion to at least partially remove effects of the RF mixer-based artifact from the RF transmit signal, wherein;

a complex RF modulator comprises a quadrature RF mixer, such that the desired frequency content and the RF mixer-based artifact are both produced by the quadrature RF mixer;

the RF mixer-based artifact comprises intermodulation content produced by the quadrature RF mixer; and

the intermodulation content and a non-linearity of the RF PA combine to provide a folding image of the desired frequency content of the RF input signal.

24. The circuitry of claim 23 wherein the folding image falls within an RF receive channel.

25. The circuitry of claim 23 wherein the folding image falls within a non-cellular communications band.

26. The circuitry of claim 25 wherein the non-cellular communications band is a Personal Handy-phone System (PHS) band.

27. A method comprising:

receiving and amplifying a radio frequency (RF) input signal to provide an RF transmit signal using an envelope power supply signal, which at least partially envelope tracks the RF transmit signal, wherein the RF input signal has a desired frequency content and an RF mixer-based artifact that includes an image of the desired frequency content; and

providing the envelope power supply signal, which includes mixer-based artifact pre-distortion to at least partially remove effects of the RF mixer-based artifact from the RF transmit signal.