Distortion correction circuit for direct conversion receiver

Abstract

A distortion correction circuit for a direct conversion receiver, the direct conversion receiver comprising a local oscillator for generating a local oscillator signal, a mixer for multiplying a radio frequency signal, and a local oscillator signal together and supplying the resultant mixer output signal to a demodulated signal, the demodulated signal path including a first low-pass filter for selecting a baseband signal at a first filter output terminal, wherein the offset correction circuit includes a squaring circuit for squaring the mixer output signal and supplying the resultant distortion estimate signal to a distortion estimate signal path, signal subtraction means for subtracting the resultant output signal at a subtraction point in the distortion estimate signal path, and adaptive processing means for equalising the transfer function of the distortion signal estimate path and the transfer function of the demodulated signal path between the mixer output and the subtraction point.

Dependencies are inferred from the claim text.