Patent ID: 7519337

Claim:
A transmitter comprising: a phase control loop synchronizing with the phase of a reference signal generated from an input signal; an amplitude control loop following the amplitude of the envelope of said reference signal; a first variable gain amplifier which is shared by said phase control loop and said amplitude control loop and combines phase information that said phase control loop outputs and envelope information that said amplitude control loop outputs by gain control; and a second variable gain amplifier for controlling an average power of said first variable gain amplifier, said second variable gain amplifier being disposed outside said phase control loop and said amplitude control loop, wherein said phase control loop is shared when said reference signal is a signal modulated by constant envelope modulation and when said reference signal is a signal modulated by nonconstant envelope modulation, said first variable gain amplifier comprising: a first variable gain amplifier body having a supply voltage terminal and a bias current detection terminal for extracting a bias current corresponding to a gain, wherein said gain changes with a change in the potential of said supply voltage terminal; and a bias control unit connected to said supply voltage terminal and said bias current detection terminal, wherein a bias control loop is provided comprising said first variable gain amplifier body and said bias control unit to control said bias current so that the gain in the case of constant envelope modulation becomes a predetermined value.