Modified switching ripple for envelope tracking system

• US 8,792,840 B2
• Filed: 07/16/2012
• Issued: 07/29/2014
• Est. Priority Date: 07/15/2011
• Status: Active Grant

• Current Assignee: Qorvo US, Inc. (Qorvo, Inc.)
• Original Assignee: RF Micro Devices Incorporated (Qorvo, Inc.)
• Inventors: Khlat, Nadim, Kay, Michael R.
• Primary Examiner(s): LE, THANH C
• Application Number:
  US13/550,049
• Publication Number:
  US 20130183916A1
• Time in Patent Office: 743 Days
• Field of Search: 455/73, 455/91, 455/115.1, 455/126, 4551271-1274, 375/295, 375/296, 330/296, 330/297
• US Class Current: 455/127.1
• CPC Class Codes: H03F 1/0227 using supply converters
• CPC Class Codes: H03F 1/305 in case of switching on or off of a power supply
• CPC Class Codes: H04B 1/0475 with means for limiting noise, interference or distortion H04B1/0483 takes precedence

Abstract

Radio frequency (RF) transmitter circuitry, which includes an RF power amplifier (PA) and an envelope tracking power supply, is disclosed. The RF PA receives and amplifies an RF input signal to provide an RF transmit signal using an envelope power supply signal. The envelope tracking power supply provides the envelope power supply signal, which has switching ripple. Further, the envelope tracking power supply operates in either a normal switching ripple mode or a modified switching ripple mode, such that during the normal switching ripple mode, the envelope power supply signal has normal switching ripple, and during the modified switching ripple mode, the envelope power supply signal has modified switching ripple. When the modified switching ripple is required, the envelope tracking power supply operates in the modified switching ripple mode.

Claims

1. Circuitry comprising:

a radio frequency power amplifier adapted to receive and amplify a radio frequency input signal to provide a radio frequency transmit signal using an envelope power supply signal; and

an envelope tracking power supply adapted to;

provide the envelope power supply signal, which has switching ripple;

operate in one of a normal switching ripple mode and a modified switching ripple mode;

during the modified switching ripple mode, the envelope power supply signal has modified switching ripple;

when the modified switching ripple is required, operate in the modified switching ripple mode; and

during the modified switching ripple mode, modify a frequency of the switching ripple, wherein;

the radio frequency transmit signal falls within one of a plurality of radio frequency communications bands;

the plurality of radio frequency communications bands comprises a first radio frequency communications band, which is about adjacent to a second radio frequency communications band; and

during the modified switching ripple mode, the one of the plurality of radio frequency communications bands is the first radio frequency communications band.

2. The circuitry of claim 1 wherein when the modified switching ripple is not required, the envelope tracking power supply is further adapted to operate in the normal switching ripple mode, such that during the normal switching ripple mode, the envelope power supply signal has normal switching ripple.

3. The circuitry of claim 1 wherein the first radio frequency communications band is a cellular communications band and the second radio frequency communications band is a non-cellular communications band.

4. The circuitry of claim 3 wherein the first radio frequency communications band is a 3rd Generation Partnership Project cellular communications band and the second radio frequency communications band is a Public Safety Band.

5. The circuitry of claim 4 wherein a frequency range of the first radio frequency communications band is between about 777 megahertz and about 787 megahertz, and a frequency range of the second radio frequency communications band is between about 763 megahertz and about 775 megahertz.

6. The circuitry of claim 1 wherein during the modified switching ripple mode, the envelope tracking power supply is further adapted to use active ripple cancellation to reduce a magnitude of the switching ripple.

7. The circuitry of claim 6 wherein an efficiency of the envelope tracking power supply is less during the modified switching ripple mode than during the normal switching ripple mode.

8. The circuitry of claim 6 wherein the envelope tracking power supply comprises a parallel amplifier adapted to partially provide the envelope power supply signal, such that a bandwidth of the parallel amplifier is greater during the modified switching ripple mode than during the normal switching ripple mode.

9. The circuitry of claim 1 wherein during the modified switching ripple mode, the frequency of the switching ripple is based on a location and a number of active resource blocks in the first radio frequency communications band.

10. The circuitry of claim 1 wherein the frequency of the switching ripple is higher during the modified switching ripple mode than during the normal switching ripple mode, such that during the modified switching ripple mode, switching ripple sidebands fall outside of the second radio frequency communications band.

11. The circuitry of claim 1 wherein the frequency of the switching ripple is lower during the modified switching ripple mode than during the normal switching ripple mode, such that during the modified switching ripple mode, switching ripple sidebands fall outside of the second radio frequency communications band.

12. The circuitry of claim 1 wherein the frequency of the switching ripple is higher during the modified switching ripple mode than during the normal switching ripple mode.

13. The circuitry of claim 1 wherein the frequency of the switching ripple is lower during the modified switching ripple mode than during the normal switching ripple mode.

14. The circuitry of claim 1 wherein during the modified switching ripple mode, the envelope tracking power supply is further adapted to modify the frequency of the switching ripple by modifying a comparison between a parallel amplifier output current and a programmable threshold.

15. The circuitry of claim 1 wherein control circuitry is adapted to select the one of the normal switching ripple mode and the modified switching ripple mode.

16. The circuitry of claim 15 wherein radio frequency transceiver circuitry comprises the control circuitry.

17. The circuitry of claim 15 further comprising the control circuitry.

18. The circuitry of claim 15 further comprising transmitter control circuitry, such that the control circuitry is further adapted to provide a transmitter configuration signal to the transmitter control circuitry, such that the transmitter configuration signal is indicative of the one of the normal switching ripple mode and the modified switching ripple mode.

19. The circuitry of claim 1 wherein

when a radio frequency output power from the radio frequency power amplifier is higher than a radio frequency output power threshold, the modified switching ripple is required.

20. A method comprising:

receiving and amplifying a radio frequency input signal to provide a radio frequency transmit signal using an envelope power supply signal;

providing the envelope power supply signal, which has switching ripple;

operating in one of a normal switching ripple mode and a modified switching ripple mode, such that during the modified switching ripple mode, the envelope power supply signal has modified switching ripple;

when the modified switching ripple is required, operating in the modified switching ripple mode; and

during the modified switching ripple mode, modifying a frequency of the switching ripple, wherein;

the radio frequency transmit signal falls within one of a plurality of radio frequency communications bands;

the plurality of radio frequency communications bands comprises a first radio frequency communications band, which is about adjacent to a second radio frequency communications band; and

during the modified switching ripple mode, the one of the plurality of radio frequency communications bands is the first radio frequency communications band.