Receiver circuit and associated method

摘要

A receiver circuit, e.g., a low-IF receiver, including two mixing paths. The two mixing paths scale an input signal respectively by two mixing gains and shift phase of the input signal respectively by two mixing phase offsets to provide two mixed signals. The two mixing gains and the two mixing phase offsets are arranged to produce an amplitude adjustment between amplitudes of the two mixed signals and a phase difference of 90 degrees plus a phase adjustment between phases of the two mixed signals. With the amplitude adjustment and/or the phase adjustment properly tuned to nonzero value(s) in association with band-pass response of the receiver circuit, image rejection can be achieved and optimized. Associated method is also disclosed.

主权项

1. A receiver circuit comprising:
two mixing paths commonly coupled to an input signal for scaling the input signal respectively by two mixing gains, shifting phase of the input signal respectively by two mixing phase offsets, and accordingly providing two mixed signals in response; and a filter coupled to the two mixing paths, and arranged to provide two filter gains and two filter phase offsets respectively for two frequency bands; wherein the two mixing gains and the two mixing phase offsets are arranged to produce an amplitude adjustment between amplitudes of the two mixed signals and a phase difference of 90 degrees plus a phase adjustment between phases of the two mixed signals, and at least one of the amplitude adjustment and the phase adjustment is arranged to be nonzero; and wherein the phase adjustment and a ratio between the amplitudes of the mixed signals are determined according to a difference between the two filter phase offsets and a ratio between the two filter gains.