Digital predistortion linearization for power amplifiers

Patent metadata

Field	Value
Publication number	US-9813089-B2
Application number	US-201715433964-A
Country	US
Kind code	B2
Filing date	Feb 15, 2017
Priority date	Nov 6, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

A cellular radio architecture that includes an RF transmitter having a digital signal processor, a digital-to-analog converter (DAC) module that converts digital bits from the processor to an analog signal, a tunable bandpass filter that removes frequencies in the analog signal outside of a frequency band of interest, and a power amplifier that amplifies the filtered analog signal. The architecture also includes a calibration feedback device that receives the amplified analog signal and provides a feedback signal to the processor for calibrating the digital signal to provide amplified amplifier pre-distortion. The processor employs a noise-shaping operation to shape the analog signal from the DAC to remove quantization noise in an immediate vicinity of the signal to improve signal-to-noise ratio, performs an infinite impulse response process to lower a noise floor in the analog signal, and provides pre-distortion of the digital signal to compensate for non-linearties of the power amplifier.

First claim

What is claimed is:

1. An RF transmitter module, said transmitter module comprising:
a digital signal processor (DSP) providing a digital signal to be transmitted;
a digital-to-analog converter (DAC) responsive to the digital signal from the DSP and a clock signal from a clock circuit, said DAC converting the digital signal to an analog signal;
a tunable bandpass filter responsive to the analog signal from the DAC and removing frequencies in the analog signal outside of a frequency band of interest; and
a power amplifier responsive to the filtered analog signal from the bandpass filter and amplifying the filtered analog signal, wherein the DSP employs a noise-shaping operation to shape the analog signal from the DAC to remove quantization noise in an immediate vicinity of the analog signal so as to improve signal-to-noise ratio.

2. The transmitter module according to claim 1 wherein the DSP performs an infinite impulse response process to lower a noise floor in the vicinity of the analog signal.

3. The transmitter module according to claim 1 wherein the DSP provides pre-distortion of the digital signal to compensate for non-linearities of the power amplifier.

4. The transmitter module according to claim 3 further comprising a calibration feedback device responsive to the amplified analog signal and providing a feedback signal to the DSP for calibrating the digital signal to provide the pre-distortion.

5. The transmitter module according to claim 1 wherein the DAC is a 4-bit DAC.

6. The transmitter module according to claim 1 wherein the DAC operates at a 5 GHz sample rate.

7. The transmitter module according to claim 1 wherein the bandwidth of the analog signal varies in the range of 20-100 MHz.

8. The transmitter module according to claim 1 wherein the DSP is implemented in CMOS.

9. The transmitter module according to claim 1 wherein the bandpass filter is an active filter.

10. The transmitter module according to claim 1 wherein the RF transmitter module is for a cellular radio.

11. The transmitter module according to claim 1 wherein the cellular radio is a vehicle cellular radio.

12. An RF transmitter module for a cellular radio, said transmitter module comprising:
a digital signal processer (DSP) providing a digital signal to be transmitted, said DSP being implemented in CMOS;
a digital-to-analog converter (DAC) responsive to the digital signal from the DSP and a clock signal from a clock circuit, said DAC converting the digital signal to an analog signal;
a tunable bandpass filter responsive to the analog signal from the DAC and removing frequencies in the analog signal outside of a frequency band of interest;
a power amplifier responsive to the filtered analog signal from the bandpass filter and amplifying the analog signal; and
a calibration feedback device responsive to the amplified analog signal and providing a feedback signal to the DSP, wherein the DSP provides pre-distortion of the digital signal to compensate for non-linearities of the power amplifier using the feedback signal.

13. The transmitter module according to claim 12 wherein the DSP employs a noise-shaping operation to shape the analog signal from the DAC to remove quantization noise in an immediate vicinity of the analog signal so as to improve signal-to-noise ratio.

14. The transmitter module according to claim 13 wherein the DSP performs an infinite impulse response process to lower a noise floor in the vicinity of the analog signal.

15. The transmitter module according to claim 12 wherein the DAC is a 4-bit DAC.

16. The transmitter module according to claim 12 wherein the DAC operates at a 5 GHz sample rate.

17. The transmitter module according to claim 12 wherein the bandwidth of the analog signal varies in the range of 20-100 MHz.

18. The transmitter module according to claim 12 wherein the cellular radio is a vehicle cellular radio.

19. An RF transmitter module for a cellular vehicle radio, said transmitter module comprising:
a digital signal processor (DSP) providing a digital signal to be transmitted;
a digital-to-analog converter (DAC) responsive to the digital signal from the DSP and converting the digital signal to an analog signal;
a tunable bandpass filter responsive to the analog signal from the DAC and removing frequencies in the analog signal outside of a frequency band of interest;
a power amplifier responsive to the filtered analog signal from the bandpass filter and amplifying the analog signal; and
a calibration feedback device responsive to the amplified analog signal and providing a feedback signal to the DSP, wherein the DSP provides pre-distortion of the digital signal to compensate for non-linearties of the power amplifier using the feedback signal, employs a noise-shaping operation to shape the analog signal from the DAC to remove quantization noise in an immediate vicinity of the analog signal so as to improve signal-to-noise ratio, and performs an infinite impulse response process to lower a noise floor in the vicinity of the analog signal.

20. The transmitter module according to claim 19 wherein the DAC is a 4-bit DAC.

Assignees

• Gm Global Tech Operations Llc

Inventors

• Talty Timothy J
• Sovero Emilio A
• Ahmed Mohiuddin
• Baringer Cynthia D
• Li James Chingwei
• Kuan Yen-Cheng
• Pan Hsuanyu

Classifications

• H04B1/0475 Primary

  with means for limiting noise, interference or distortion (H04B1/0483 takes precedence) · CPC title

• H04B2001/0425

  with linearisation using predistortion · CPC title

• H03M3/408

  by the use of an LC circuit · CPC title

• H03M1/365

  the voltage divider being a single resistor string · CPC title

• H04L1/0071

  Use of interleaving (interleaving per se H03M13/27) · CPC title