Patent ID: 6801581
Filing Date: 2004-10-05
Classification: H03C,H04L

Abstract:
A method for reducing a DC offset in a transmitter, the transmitter having a transmission path with an IQ modulator and a feedback path with an IQ demodulator, the method comprising:providing a predetermined signal to the input of said IQ modulator and transmitting said signal; estimating a DC offset of said IQ demodulator from a received version of said transmitted signal; adaptively estimating a DC offset of said IQ modulator at least partially from said demodulator DC offset; subtracting said estimated demodulator DC offset from said feedback path; and subtracting said estimated modulator DC offset from said transmission path, wherein said estimating said demodulator DC offset comprises averaging a received signal along said feedback path, and wherein adaptively estimating said modulator DC offset comprises generating a difference signal between said received signal and said estimated demodulator DC offset and subtracting a modified rotated version of said difference signal from a previous value of said modulator DC offset.