High Efficiency Amplification

Abstract

A radio frequency amplification stage comprising: an amplifier for receiving an input signal to be amplified and a power supply voltage; and a power supply voltage stage for supplying said power supply voltage, comprising: means for providing a reference signal representing the envelope of the input signal; means for selecting one of a plurality of supply voltage levels in dependence on the reference signal; and means for generating an adjusted selected power supply voltage, comprising an ac amplifier for amplifying a difference between the reference signal and one of the selected supply voltage level or the adjusted selected supply voltage level, and a summer for summing the amplified difference with the selected supply voltage to thereby generate the adjusted supply voltage.

What is claimed is: 
     
         1 . A power supply system, comprising:
 a power source configured to generate first output power;   a power supply configured to generate second output power;   a power combiner circuit configured to combine the first output power with the second output power to generate combined, third output power; and   a feedback circuit coupled to receive a feedback signal indicative of the combined output power through a feedback loop, the feedback circuit configured to compare the feedback signal with a control signal and generate a power supply control signal for controlling the power supply based on a difference between the feedback signal and the control signal, and wherein the power source is not controlled based on the difference between the feedback signal and the control signal.   
     
     
         2 . The power supply system of  claim 1 , wherein the power source is a DC (direct current) power source. 
     
     
         3 . The power supply system of  claim 1 , wherein the power source is another power supply configured to generate the first output power. 
     
     
         4 . The power supply system of  claim 1 , wherein the feedback circuit includes an error amplifier configured to compare the third output power with the predetermined control signal to generate the power supply control signal. 
     
     
         5 . The power supply system of  claim 1 , wherein the power supply control signal is configured to decrease the second output power from the power supply if the third output power is higher than the control signal, and increase the second output power from the power supply if the third output power is lower than the control signal. 
     
     
         6 . The power supply system of  claim 1  further comprising: a RF power amplifier configured to receive and amplify a RF input signal to generate a RF output signal under control of the combined output power. 
     
     
         7 . The power supply system of  claim 1  further comprising: circuitry configured to generate the control signal based on an amplitude of the RF input signal. 
     
     
         8 . The power supply system of  claim 1  wherein the combiner is a transformer. 
     
     
         9 . A power supply system for providing power to a radio frequency (RF) power amplifier, comprising:
 a power source configured to generate first output power;   a power supply configured to generate second output power;   a power combiner circuit configured to combine the first output power with the second output power to generate combined output power for providing power to the RF power amplifier, the RF power amplifier receiving and amplifying a RF input signal to generate a RF output signal under control of the combined output power; and   a feedback circuit coupled to receive a feedback signal indicative of an amplitude of the RF output signal through a feedback loop, the feedback circuit configured to compare the feedback signal with a control signal and generate a power supply control signal for controlling the power supply based on a difference between the feedback signal and the control signal, and wherein the power source is not controlled based on the difference between the feedback signal and the control signal.   
     
     
         10 . The power supply system of  claim 9 , wherein the power supply control signal is configured to decrease the second output power from the power supply if the RF output signal is higher than the control signal, and increase the second output power from the power supply if the RF output signal is lower than the control signal. 
     
     
         11 . The power supply system of  claim 10  wherein the combiner is a transformer.