A 4-phase blocker tolerant wideband receiver with MMSE harmonic rejection equalizer

Abstract

This paper presents a blocker tolerant low-noise wideband receiver that employs digital harmonic rejection equalizer to suppress high order harmonic interferers. Unlike the commonly employed 8-phase harmonic rejection mixers (HRMs), the proposed wideband receiver suppresses any of the harmonic interferers including the seventh and ninth. The wideband receiver employs a two-path front-end structure, consisting of a highly linear mixer-first primary path and gm-first secondary path. An adaptive minimum mean-squared error (MMSE) harmonic rejection equalizer is employed that minimizes the desired signal distortion in the mean-squared error sense in the presence of arbitrary harmonic interferers and the correlated noise between the two paths. Using two sets of 4-phase clocks, a 100-1450MHz receiver that achieves HRR >75dB up to the ninth harmonic while being robust to mismatches is implemented.