Amplifier control apparatus

Abstract

An apparatus for controlling a pulse width modulation (PWM) amplifier is disclosed. In one aspect, the apparatus includes a delay circuit configured to delay an input signal and provide the delayed input signal to the PWM amplifier. The apparatus also includes a controller configured to generate and provide a supply voltage to the PWM amplifier based at least in part on the input signal such that the PWM amplifier generates an output signal based at least partially on the delayed input signal and the supply voltage.

What is claimed is: 
     
         1 . An apparatus for controlling a pulse width modulation (PWM) amplifier, comprising:
 a delay circuit configured to delay an input signal and provide the delayed input signal to the PWM amplifier; and   a controller configured to dynamically adjust a supply voltage to the PWM amplifier based on at least the input signal and an adjustable PRESCALE, the adjustable PRESCALE scaling the supply voltage based on a linear function of the input signal detected over a sample time period.   
     
     
         2 . The apparatus of  claim 1 , wherein the linear function is based on a predetermined scale value. 
     
     
         3 . The apparatus of  claim 1 , wherein the controller is further configured to dynamically adjust the supply voltage based on a SLOPE. 
     
     
         4 . The apparatus of  claim 1 , wherein the controller is further configured to dynamically adjust the supply voltage based on an INTERCEPT. 
     
     
         5 . The apparatus of  claim 1 , wherein the controller is further configured to dynamically adjust the supply voltage based on an UPPERBOUND. 
     
     
         6 . The apparatus of  claim 1 , wherein the controller is further configured to dynamically adjust the supply voltage based on a LOWERBOUND. 
     
     
         7 . The apparatus of  claim 1 , wherein the controller comprises:
 a peak hold circuit configured to track peaks of the input signal and generate a signal envelope for a predetermined sample period; and   a boost controller configured to transform the signal envelope into a PWM control voltage.   
     
     
         8 . The apparatus of  claim 7 , wherein the peak hold circuit, the boost controller and the delay circuit are included in a digital signal processor (DSP). 
     
     
         9 . The apparatus of  claim 7 , wherein the boost controller comprises:
 a prescale unit configured to convert the signal envelope to a PWM amplifier rail voltage;   a linear mapping unit configured to substantially linearly map the PWM amplifier rail voltage to the PWM control voltage; and   a control signal generator configured to maintain the PWM control voltage within a predetermined voltage range.   
     
     
         10 . The apparatus of  claim 7 , wherein the controller further comprises an enable unit configured to turn on and off the boost controller. 
     
     
         11 . The apparatus of  claim 7 , wherein the controller further comprises a boost converter configured to maintain the level of the PWM control voltage at a predetermined reference voltage or within a predetermined voltage range. 
     
     
         12 . The apparatus of  claim 11 , wherein the boost converter comprises a switch mode power supply (SMPS). 
     
     
         13 . The apparatus of  claim 1 , further comprising a digital to analog converter configured to convert the delayed input signal into an analog signal and to provide the analog signal to the PWM amplifier. 
     
     
         14 . An apparatus for controlling an amplifier, comprising:
 a delay circuit configured to delay an input signal and provide the delayed input signal to the amplifier; and   a controller configured to dynamically adjust a supply voltage to the amplifier based on at least the input signal and an adjustable PRESCALE, the adjustable PRESCALE scaling the supply voltage based on a linear function of the input signal detected over a sample time period.   
     
     
         15 . The apparatus of  claim 14 , wherein the delay circuit is further configured to provide the delayed input signal to the amplifier in substantial synchronization with the supply voltage. 
     
     
         16 . The apparatus of  claim 14 , wherein the amplifier comprises a pulse width modulation (PWM) amplifier. 
     
     
         17 . A pulse width modulation (PWM) system, comprising:
 a delay circuit configured to delay an input signal;   a pulse width modulation (PWM) amplifier configured to generate an output signal based at least partially on the delayed input signal and the supply voltage, and provide the output signal to a load; and   a controller configured to dynamically adjust a supply voltage to the PWM amplifier based on at least the input signal and an adjustable PRESCALE, the adjustable PRESCALE scaling the supply voltage based on a linear function of the input signal detected over a sample time period.   
     
     
         18 . The PWM system of  claim 17 , wherein the controller is further configured to monitor the output signal of the PWM amplifier to be supplied to the load, and adjust the supply voltage based on the monitored output. 
     
     
         19 . The PWM system of  claim 17 , wherein the PWM amplifier comprises a feedback loop configured to maintain the supply voltage at a predetermined reference voltage or within a predetermined voltage range. 
     
     
         20 . The PWM system of  claim 17 , wherein the controller comprises:
 a peak hold circuit configured to track peaks of the input signal and generate a signal envelope for a predetermined sample period;   a boost controller configured to transform the signal envelope into a PWM control voltage; and   a boost converter configured to maintain the level of the PWM control voltage at a predetermined reference voltage or within a predetermined voltage range.