COMPENSATION OF FREQUENCY DEPENDENT QUADRATURE IMBALANCE IN A ZERO-IF DOWNCONVERTER
Original Publication Date: 1999-Jun-01
Included in the Prior Art Database: 2002-Aug-15
Radio receivers traditionally employ an interme- diate frequency (IF) section to perform the major portion of the radio's selectivity. The process of translating a signal down to a zero Hertz intermedi- ate frequency is known as zero-IF downconversion. One of the problems associated with a zero-IF downconverter is amplitude and phase imbalance in the quadrature oscillator and mixers along with amplitude and phase mismatch between the low pass filters in each quadrature path. Prior inventions have compensated for the imbalance due to the oscillator and mixers which is constant across the frequency bandwidth of the received signal [l]. This invention is novel in that it also.compensates for the phase imbalance due to the mismatch between the low pass filters which varies across the bandwidth of the received signal.