Apparatus and methods for envelope trackers

Patent metadata

Field	Value
Publication number	US-9584070-B2
Application number	US-201514805343-A
Country	US
Kind code	B2
Filing date	Jul 21, 2015
Priority date	Apr 25, 2011
Publication date	Feb 28, 2017
Grant date	Feb 28, 2017

Abstract

Apparatus and methods for envelope tracking are disclosed. In one embodiment, a power amplifier system including a power amplifier and an envelope tracker is provided. The power amplifier is configured to amplify a radio frequency (RF) signal, and the envelope tracker is configured to control a supply voltage of the power amplifier using an envelope of the RF signal. The envelope tracker includes a buck converter for generating a buck voltage from a battery voltage and a digital-to-analog conversion (DAC) module for adjusting the buck voltage based on the envelope of the RF signal to generate the supply voltage for the power amplifier.

First claim

What is claimed is:

1. A power amplifier system comprising:
a power amplifier configured to amplify a radio frequency signal to generate an amplified radio frequency signal, the power amplifier electrically powered by a power amplifier supply voltage; and
an envelope tracker including an output configured to generate the power amplifier supply voltage and an input configured to receive an envelope signal corresponding to an envelope of the radio frequency signal, the envelope tracker including a control circuit, a buck converter including an output electrically connected to the output of the envelope tracker, and a digital-to-analog converter module including an output electrically connected to the output of the envelope tracker, the control circuit configured to control the buck converter and the digital-to-analog converter module based on the envelope signal, the buck converter providing more output power than the digital-to-analog converter module for frequency components of the envelope signal that are less than about 200 kHz.

2. The power amplifier system of claim 1 further comprising a transceiver configured to generate the radio frequency signal and the envelope signal.

3. The power amplifier system of claim 1 wherein the control circuit includes a filter configured to filter the envelope signal to generate a filtered envelope signal.

4. The power amplifier system of claim 3 wherein the filter is configured to receive one or more feedback signals including the power amplifier supply voltage.

5. The power amplifier system of claim 3 wherein the control circuit further includes a ripple control circuit configured to control a plurality of switches of the buck converter based on the filtered envelope signal.

6. The power amplifier system of claim 3 wherein the control circuit further includes a digital shaping and delay block configured to generate a shaped envelope signal based on shaping and delaying the filtered envelope signal.

7. The power amplifier system of claim 6 wherein the control circuit further includes a decoder configured to control the digital-to-analog converter module based on decoding the shaped envelope signal.

8. The power amplifier system of claim 1 wherein the digital-to-analog converter module includes a push digital-to-analog converter and a pull digital-to-analog converter, the control circuit configured to control the push digital-to-analog converter to increase the power amplifier supply voltage when the envelope signal increases and to control the pull digital-to-analog converter to decrease the power amplifier supply voltage when the envelope signal decreases.

9. An envelope tracker for supplying power to a power amplifier that amplifies a radio frequency signal, the envelope tracker comprising:
an output configured to generate a power amplifier supply voltage;
a buck converter including an output electrically connected to the output of the envelope tracker;
a digital-to-analog converter module including an output electrically connected to the output of the envelope tracker; and
a control circuit configured to control the buck converter and the digital-to-analog converter module based on an envelope signal corresponding to an envelope of the radio frequency signal, the buck converter providing more output power than the digital-to-analog converter module for frequency components of the envelope signal that are less than about 200 kHz.

10. The envelope tracker of claim 9 wherein the control circuit includes a filter configured to filter the envelope signal to generate a filtered envelope signal.

11. The envelope tracker of claim 10 wherein the filter is configured to receive one or more feedback signals including the power amplifier supply voltage.

12. The envelope tracker of claim 10 wherein the control circuit further includes a ripple control circuit configured to control a plurality of switches of the buck converter based on the filtered envelope signal.

13. The envelope tracker of claim 10 wherein the control circuit further includes a digital shaping and delay block configured to generate a shaped envelope signal based on shaping and delaying the filtered envelope signal.

14. The envelope tracker of claim 13 wherein the control circuit further includes a decoder configured to control the digital-to-analog converter module based on decoding the shaped envelope signal.

15. The envelope tracker of claim 9 wherein the digital-to-analog converter module includes a push digital-to-analog converter and a pull digital-to-analog converter, the control circuit configured to control the push digital-to-analog converter to increase the power amplifier supply voltage when the envelope signal increases and to control the pull digital-to-analog converter to decrease the power amplifier supply voltage when the envelope signal decreases.

16. A method of envelope tracking in a power amplifier system, the method comprising:
amplifying a radio frequency signal using a power amplifier;
controlling an output of a buck converter based on an envelope signal corresponding to an envelope of the radio frequency signal;
controlling an output of a digital-to-analog converter module based on the envelope signal;
generating a power amplifier supply voltage based on the output of the buck converter and the output of the digital-to-analog converter module;
powering the power amplifier with the power amplifier supply voltage; and
providing more output power with the buck converter than with the digital-to-analog converter module for frequency components of the envelope signal that are less than about 200 kHz.

17. The method of claim 16 further comprising generating the radio frequency signal and the envelope signal using a transceiver.

18. The method of claim 16 further comprising filtering the envelope signal to generate a filtered envelope signal.

19. The method of claim 18 further comprising controlling a plurality of switches of the buck converter based on the filtered envelope signal.

20. The method of claim 18 further comprising generating a shaped envelope signal based on shaping and delaying the filtered envelope signal, decoding the shaped envelope signal to generate a decoded signal, and controlling the digital-to-analog converter module using the decoded signal.

Assignees

• Skyworks Solutions Inc

Inventors

• Balteanu Florinel G
• Khesbak Sabah
• Tkachenko Yevgeniy A
• Ripley David Steven
• Thompson Robert John

Classifications

• H03F3/19

  with semiconductor devices only · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F1/0227

  using supply converters · CPC title

• H03F3/245

  with semiconductor devices only · CPC title

• H03F2200/555

  A voltage generating circuit being realised for biasing different circuit elements · CPC title