Temperature compensated power amplifier gain

Abstract

A temperature compensation circuit comprises a temperature coefficient circuit that generates a temperature coefficient that is temperature dependent and a compensation circuit that generates a compensation signal based on an indication of temperature of an amplifier and the temperature coefficient, and based on the compensation signal, a gain of the amplifier is adjusted to improve amplifier linearity during data bursts.

1 . (canceled) 
     
     
         2 . A compensation circuit for a power amplifier, comprising:
 a sampling circuit configured to provide an indication of a temperature change of a power amplifier when the power amplifier is energized;   a coefficient circuit configured to provide a temperature coefficient; and   a multiplier configured to multiply the indication of the temperature change by the temperature coefficient to generate a compensation signal.   
     
     
         3 . The compensation circuit of  claim 2  wherein the compensation signal is used to adjust a bias of the power amplifier. 
     
     
         4 . The compensation circuit of  claim 2  wherein a reference signal is adjusted based on the compensation signal to provide a bias signal. 
     
     
         5 . The compensation circuit  claim 2  wherein the sampling circuit is further configured to capture an indication of an initial temperature of the power amplifier when the power amplifier is energized. 
     
     
         6 . The compensation circuit of  claim 2  wherein the indication of the temperature change of the power amplifier is relative to an initial temperature of the power amplifier. 
     
     
         7 . The compensation circuit of  claim 2  wherein the temperature coefficient is temperature dependent. 
     
     
         8 . The compensation circuit of  claim 2  wherein the coefficient circuit includes a subtractor configured to subtract a base temperature coefficient from an indication of average temperature of the power amplifier. 
     
     
         9 . The compensation circuit of  claim 8  wherein the coefficient circuit further includes a limiter configured to output a zero value as the temperature coefficient when the output of the subtractor is a negative value. 
     
     
         10 . The compensation circuit of  claim 2  wherein the coefficient circuit includes a first digital register configured to store a base coefficient value and a second digital register configured to store a value to set a rate of change of the temperature coefficient over temperature. 
     
     
         11 . A method to generate a temperature compensation signal for a power amplifier, the method comprising:
 provide, with a sampling circuit, an indication of a temperature change of the power amplifier when a power amplifier is energized;   generate a temperature coefficient based at least in part on an indication of an average temperature of the power amplifier, a base temperature coefficient, and a value to set a rate of change of the temperature coefficient over temperature; and   multiply the indication of the temperature change by the temperature coefficient to generate a temperature compensation signal.   
     
     
         12 . The method of  claim 11  further comprising adjusting a reference signal based on the temperature compensation signal to generate a bias signal for the power amplifier. 
     
     
         13 . The method of  claim 11  further comprising capturing, with the sampling circuit, an indication of an initial temperature of the power amplifier when the power amplifier is energized. 
     
     
         14 . The method of  claim 11  wherein said generating the temperature coefficient includes subtracting the base temperature coefficient from the indication of the average temperature of the power amplifier. 
     
     
         15 . The method of  claim 11  further comprising limiting the temperature coefficient to a positive value. 
     
     
         16 . A power amplifier module comprising:
 a first die mounted to a substrate and including a power amplifier configured to receive a bias signal based at least in part on a compensation signal; and   a second die mounted to the substrate and including a sampling circuit configured to provide an indication of a temperature change when the power amplifier is energized, a coefficient circuit configured to provide a temperature coefficient, and a multiplier configured to multiply the indication by the temperature coefficient to generate the compensation signal.   
     
     
         17 . The power amplifier module of  claim 16  wherein the first die further includes a temperature sensor configured to sense a temperature of the power amplifier. 
     
     
         18 . The power amplifier module of  claim 16  wherein a temperature compensation circuit includes the sampling circuit, the coefficient circuit, and the multiplier. 
     
     
         19 . The power amplifier module of  claim 16  wherein the second die further includes a combining circuit configured to combine a reference signal and the compensation signal to generate a bias current. 
     
     
         20 . The power amplifier module of  claim 19  wherein the second die further includes a bias circuit configured to convert the bias current to the bias signal. 
     
     
         21 . A wireless communication device including the power amplifier module of  claim 16 .