Rf power amplifier

Abstract

The RF power amplifier includes first and second amplifiers Q 1 and Q 2 as final-stage amplification power devices connected in parallel between an input terminal RF_In and an output terminal RF_Out. The amplifiers Q 1 and Q 2 are formed on one semiconductor chip. The first bias voltage Vg 1 of the amplifier Q 1 is set to be higher than the second bias voltage Vg 2 of the amplifier Q 2 so that the amplifier Q 1 is operational between Class B and AB, and Q 2 is operational in Class C. The first effective device size Wgq 1 of the amplifier Q 1 is intentionally set to be smaller than the second effective device size Wgq 2 of the amplifier Q 2 beyond a range of a manufacturing error of the semiconductor chip. An RF power amplifier that exhibits a high power-added efficiency characteristic regardless of whether the output power is High or Low can be materialized.

1 . A high-frequency power amplifier comprising:
 a plurality of power amplifiers disposed in parallel; and   a bias control circuit which determines an operation mode depending on a method of modulating an input signal and individually controls biases of the power amplifiers depending on the determined operation mode,   wherein the operation mode comprises a linear amplification mode for execution of linear amplification, and a nonlinear amplification mode for execution of nonlinear amplification, and   the bias control circuit makes biases of the power amplifiers substantially equal when the operation mode is the linear amplification mode, and makes the biases of the power amplifiers different from each other when the operation mode is the nonlinear amplification mode.   
     
     
         2 . The high-frequency power amplifier of  claim 1 , wherein the bias control circuit sets biases of the power amplifiers so that the power amplifiers are operational in any one of operating classes between Class A and B when the input signal requires linear amplification, and
 the bias control circuit sets the bias of at least one power amplifier so that the at least one power amplifier is operational in any one of operating classes between Class A and B, and sets the biases of the remaining power amplifiers so that the remaining power amplifier are operational in any one of operating classes between Class B and C when the input signal requires nonlinear amplification.   
     
     
         3 . The high-frequency power amplifier of  claim 1 , wherein a line for the input signal is adapted for differential input. 
     
     
         4 . The high-frequency power amplifier of  claim 1 , wherein a piece of information for controlling activation and deactivation of an antenna switch for cutting a line to an antenna is superposed on an output signal from the power amplifier. 
     
     
         5 . The high-frequency power amplifier of  claim 1 , further comprising:
 a signal distributing part for supplying the input signal to the power amplifiers; and   a signal synthesizing part for synthesizing high-frequency signals amplified by the power amplifiers.   
     
     
         6 . high-frequency power amplifier of  claim 5 , wherein the signal distributing part includes a first circuit which makes a phase difference between signals resulting from distribution by the signal distributing part 90 degrees, and
 the signal synthesizing part includes a second circuit which makes the phase difference between the signals subjected to amplification by the power amplifiers 0 degree.   
     
     
         7 . The high-frequency power amplifier of  claim 6 , wherein the first and second circuits are each composed of a distributed parameter line. 
     
     
         8 . The high-frequency power amplifier of  claim 6 , wherein the first and second circuits are each composed of a lumped-parameter device. 
     
     
         9 . The high-frequency power amplifier of  claim 1 , wherein the high-frequency power amplifier is a multistage amplifier including a plurality of amplifier stages, each composed of a group of power amplifiers disposed in parallel, and
 the plurality of amplifier stages are connected in series.   
     
     
         10 . The high-frequency power amplifier of  claim 1 , further comprising
 a preceding stage amplifier having an output terminal connected to an input of the power amplifier,   wherein the preceding stage amplifier is composed of one of an independent power amplifier and a set of independent power amplifiers connected in series, and   the power amplifiers disposed in parallel constitutes a multistage amplifier together with the preceding stage amplifier, and works as a final stage of the multistage amplifier.   
     
     
         11 . The high-frequency power amplifier of  claim 9 , wherein the bias control circuit controls only a final stage of the multistage amplifier in bias. 
     
     
         12 . The high-frequency power amplifier of  claim 9 , wherein the bias control circuit controls all stages of first to final stages of the multistage amplifier in bias. 
     
     
         13 . The high-frequency power amplifier of  claim 1 , wherein the power amplifiers and bias control circuit are formed on a monolithic board. 
     
     
         14 . A high-frequency power amplifier supporting a multimode, comprising a plurality of power amplifiers connected in parallel,
 wherein the power amplifiers are individually controlled in bias depending on a method of modulating an input signal,   the power amplifiers are switched to a linear amplification mode or nonlinear amplification mode based on information concerning a modulation method, use of which will be started, and   control operations are performed so that characteristic curves of power gain, power-added efficiency and phase difference are made continuous, without switching between the linear amplification mode and the nonlinear amplification mode depending on the amount of input power.   
     
     
         15 . A high-frequency power amplifier supporting a multimode of  claim 14 , wherein biases of the power amplifiers are made substantially equal when the modulation method requires the linear amplification mode, and
 biases of the power amplifiers are made different when the modulation method requires the nonlinear amplification mode.