Modulation agnostic digital hybrid mode power amplifier system and method

Patent metadata

Field	Value
Publication number	US-9866414-B2
Application number	US-201414337004-A
Country	US
Kind code	B2
Filing date	Jul 21, 2014
Priority date	Dec 21, 2009
Publication date	Jan 9, 2018
Grant date	Jan 9, 2018

Abstract

A RF-digital hybrid mode power amplifier system for achieving high efficiency and high linearity in wideband communication systems is disclosed. The present invention is based on the method of adaptive digital predistortion to linearize a power amplifier in the RF domain. The present disclosure enables a power amplifier system to be field reconfigurable and support multi-modulation schemes (modulation agnostic), multi-carriers and multi-channels. As a result, the digital hybrid mode power amplifier system is particularly suitable for wireless transmission systems, such as base-stations, repeaters, and indoor signal coverage systems, where baseband I-Q signal information is not readily available.

First claim

We claim:

1. A digital predistortion system for linearizing the output of power amplifiers comprising:
an input configured to receive an input signal for wireless communications;
at least one power amplifier for outputting an amplified signal;
a feedback path including at least one feedback signal derived from the amplified signal, wherein the at least one feedback signal includes a representation of a noise characteristic of the power amplifier;
digital predistortion logic for predistorting the input signal and supplying a predistorted signal to the at least one power amplifier, wherein the digital predistortion logic complies at least in part with the equation:

z
⁡

(
n
)

=

∑

i
=
0

n
-
1

⁢

x
i

⁡

(

n
-
i

)

⁢

(

∑

j
=
0

k
-
1

⁢

a
ij

⁢



x
i

⁡

(

n
-
i

)



j

)

,

where z(n) is a predistortion function, n is a variable representing time, x t is a transmission (input) signal, i, j, and k are counters for summation, N is a number of data per block, and a ij are predistortion coefficients;
delay estimation logic configured to estimate the delay between the input signal and the feedback signal by maximizing an amplitude difference correlation of the input signal and the feedback signal, wherein the delay estimation logic selects between an integer delay when the amplitude difference correlation is odd and between a fractional delay when the amplitude difference correlation is even;
a memory for storing the predistortion coefficients;
estimator logic configured to determine the predistortion coefficients, wherein the estimator logic includes a least square algorithm, and wherein the predistortion coefficients are based at least in part on the estimated delay; and
a multiplexor configured to receive the predistortion coefficients from the memory and configured to receive the predistortion coefficients from the estimator logic, wherein the multiplexor selects either the predistortion coefficients received from the memory or the predistortion coefficients received from the estimator logic, and wherein the multiplexor supplies the selected predistortion coefficients to the digital predistortion logic.

2. The digital predistortion system of claim 1 further comprising a digital module that includes one or more of a digital field programmable gate array, digital-to-analog converters, analog-to-digital converters, and a phase-locked loop.

3. The digital predistortion system of claim 1 wherein the power amplifier comprises at least one of an up-converter for real signals and an analog quadrature modulator for real and complex signals, a high power amplifier with multi-stage drive amplifiers, and a temperature sensor.

4. The digital predistortion system of claim 1 , further comprising phase shift logic configured to compensate for a phase offset between the input signal and the feedback signal.

5. The digital predistortion system of claim 1 , further comprising magnitude gain logic configured to compensate for a gain in the feedback signal.

6. The digital predistortion system of claim 1 , wherein the predistortion coefficients stored in the memory are determined by a QR-RLS algorithm.

7. The digital predistortion system of claim 1 , wherein the delay estimation logic includes a delay selection multiplexor configured to select between the integer delay and the fractional delay.

8. The digital predistortion system of claim 1 , wherein the fractional delay is a half-sample delay.

9. The digital predistortion system of claim 1 , wherein the predistortion coefficients are based at least in part on the estimated delay and at least in part on a weighting factor.

10. The digital predistortion system of claim 1 , wherein the digital predistortion logic comprises a plurality of finite impulse response (FIR) filters.

Assignees

• Dali Systems Co Ltd

Inventors

• Kim Wan Jong
• Cho Kyoung Joon
• Stapleton Shawn Patrick
• Xiao Ying

Classifications

• H03F2200/207

  A hybrid coupler being used as power measuring circuit at the output of an amplifier circuit · CPC title

• H03F2200/447

  the amplifier being protected to temperature influence · CPC title

• H03F1/3258 Primary

  based on polynomial terms · CPC title

• H03F2200/451

  the amplifier being a radio frequency amplifier · CPC title

• H03F3/19

  with semiconductor devices only · CPC title