Patent ID: 7133649

Claim:
A negative feedback amplifier for a transmitter, comprising: a vector corrector for correcting at least one of a phase and an amplitude of an in-phase component and a quadrature component of an input baseband signal containing data to be transmitted and outputting said corrected one; an adder for adding a feedback signal of said in-phase component to said in-phase component of an output from said vector corrector and a feedback signal of said guadrature component to said quadrature component of said output from said vector corrector, respectively; a modulator for orthogonally modulating said in-phase components and said guadrature components of outputs of said adder; a power amplifier for amplifying an output of said modulator; a demodulator for orthogonally demodulating a part of an output of said power amplifier and outputting said feedback signals of said in-phase component and said quadrature component, wherein said vector corrector performs a correcting operation of canceling an error of at least one of the phase and the amplitude of said in-phase component and said quadrature component occurring in said demodulator; and an error detecting unit, wherein when testing signals of the in-phase component and the quadrature component having a predetermined phase and amplitude is provided as said input baseband signal to said negative feedback amplifier, said error detecting unit performes a phase and amplitude comparisons between the in-phase component between said adders and said modulator and the in-phase component of said testing signal and between the quadrature component therebetween and the quadrature component thereof, and detects at least one of the phase error and the amplitude error by said comparison.