A 500MHz– 2.7 GHz 8-path weaver downconverter with harmonic rejection and embedded filtering

Abstract

This paper describes a combination of a Weaver mixer and an N-path filter for a superheterodyne receiver with a reconfigurable frequency plan. It uses an N-path topology driven with two different frequencies, effectively realizing a frequency shift together with band-pass filtering. To reduce transfers via harmonics other than the fundamental, a harmonic rejection scheme is used. A 28 nm FDSOI CMOS implementation with 30 dB harmonic rejection and an out-of-band IIP3 of >20 dBm is demonstrated.

N-path filters and mixer-first receivers: A review

“…Using 110MHz IF-frequency, 2.8dB Noise Figure and -8dBm IIP3 is achieved. Image rejection and harmonic rejection is crucial in heterodyne receivers, as explored further in [47]. A flexible Weaver architecture augmented with harmonic rejection was proposed, with a tunable IF-frequency between 100 and 500MHz.…”

“…3. Using a second set of switches that sense the capacitor voltages can largely eliminate the problem [22,47].…”