Dynamic bias control

Abstract

Systems and methods for controlling a power amplifier includes combining a digital modulated data signal with a digital bias signal to generate a combined digital signal, the digital bias signal generated based on an envelope for the modulated data signal; converting, by a digital-to-analog converter, the combined digital signal into a combined analog signal, the combined analog signal comprising an analog modulated data signal and an analog envelope bias signal; and separating the analog modulated data signal and the analog bias signal onto separate signal paths, wherein the converting is performed using a single digital-to-analog converter.

1 - 26 . (canceled) 
     
     
         27 . A system comprising:
 a digital envelope detector operable to generate a digital bias according to a digital signal;   a digital-to-analog converter (DAC) operable to generate a biased analog signal according to the digital signal and the digital bias;   a power amplifier operable to generate an amplifier output according to an amplifier input and an amplifier control;   a high pass filter operable to attenuate an analog bias of the biased analog signal to generate the amplifier input; and   a low pass filter operable to pass the analog bias of the biased analog signal to generate the amplifier control.   
     
     
         28 . The system of  claim 27 , wherein the control input of the power amplifier is operable to control a bias of the power amplifier. 
     
     
         29 . The system of  claim 27 , wherein the digital signal comprises a data signal modulated on a carrier. 
     
     
         30 . The system of  claim 27 , wherein the DAC comprises a digital combiner. 
     
     
         31 . The system of  claim 27 , wherein the system comprises an adaptive filter operably coupled between the digital envelope detector and the DAC. 
     
     
         32 . The system of  claim 31 , wherein the system comprises a return path operably coupled to the amplifier output. 
     
     
         33 . The system of  claim 32 , wherein the return path comprises an analog-to-digital converter (ADC). 
     
     
         34 . The system of  claim 32 , wherein an output of the ADC provides a training signal to the adaptive filter. 
     
     
         35 . The system of  claim 31 , wherein the adaptive filter is operable to measure a signal distortion and provide a pre-distortion. 
     
     
         36 . The system of  claim 27 , wherein the system comprises a bias conditioner to extract an original envelope for a modulated data signal in accordance with a phase of the amplifier output. 
     
     
         37 . A method comprising:
 generating a digital bias according to an envelope of a digital signal;   combining the digital signal with the digital bias to generate a biased digital signal;   converting, by a digital-to-analog converter (DAC), the biased digital signal into a biased analog signal, wherein the biased analog signal comprises a high frequency analog modulated data signal and a low frequency analog envelope bias signal;   separating the high frequency analog modulated data signal from the low frequency analog envelope bias signal; and   amplifying, using a power amplifier, the high frequency analog modulated data signal by a gain determined according to the low frequency analog envelope bias signal.   
     
     
         38 . The method of  claim 37 , wherein the combining is performed using the DAC. 
     
     
         39 . The method of  claim 37 , wherein the separating comprises filtering out the low frequency analog envelope bias signal from the analog RF signal and passing the high frequency analog modulated data signal to the power amplifier for amplification. 
     
     
         40 . The method of  claim 37 , wherein the separating comprises filtering out the high frequency analog modulated data signal from the analog RF signal and passing the low frequency analog envelope bias signal to a control input of the power amplifier to control the bias of the power amplifier. 
     
     
         41 . The method of  claim 37 , wherein the method comprises computing a complement of the envelope. 
     
     
         42 . The method of  claim 37 , wherein the method comprises filtering, using an adaptive filter, the digital bias signal prior to combining it with the digital RF signal. 
     
     
         43 . The method of  claim 37 , wherein the low frequency analog envelope bias signal is substantially in phase with the high frequency analog modulated data signal at the power amplifier. 
     
     
         44 . The method of  claim 37 , wherein the method comprises:
 providing the high frequency analog modulated data signal to an input of the power amplifier; and   providing the low frequency analog envelope bias signal to a control input of the power amplifier.   
     
     
         45 . The method of  claim 37 , wherein the method comprises pre-distorting, using an adaptive filter, the digital signal according to a measured signal distortion in the amplified high frequency analog modulated data signal. 
     
     
         46 . The method of  claim 37 , wherein the method comprises extracting, using a bias conditioner to, an original envelope for a modulated data signal in accordance with a phase of the amplifier output.