A tunable reflection-mode N-path filter using 45-nm SOI CMOS

A tunable 700-to 3000-MHz reflection-mode N-path filter in 45-nm SOI CMOS is presented. The filter employs a reflective architecture in which two eight-phase passive mixers are combined with an external 90-degree hybrid coupler to realize a circuit that passes in-band signals and absorbs out-of-band signals. The filter achieves insertion loss 0.8 to 2.1 dB and noise figure of 0.9 to 3.9 dB over the entire tuning range, while consuming 4 to 8 mW from a 0.9-V supply. Input-referred 1-dB compression point is +0 dBm, and input-referred third-order intercept point (HP3) is +10 dBm in-band and +22 dBm out-of-band.