Abstract
N-path filters show promise to realize tunable, high- quality on-chip filters. However, N-path filters remain restricted to sub-2 GHz operation, low frequency selectivity, and ≈0 dBm power handling. We circumvent these issues through: 1) the concept of frequency-translational higher order N-path filters that uses baseband/intermediary-frequency nodes/resonators to break the trade-off between operating frequency and loss/power consumption; 2) a new complementary Nakagome-charge-pump- based clock booster circuit to enhance the power handling of the N-path filters; and 3) the usage of N-phase paths with overlapping local oscillator (LO’s) to enable a higher frequency of operation. When combined, these innovations have resulted in a higher order N-path band-pass filter that emulates the transmission profile of a third order elliptical bandpass filter (BPF) with two shunt resonators and two series resonators. Our prototype was implemented in a standard 65 nm CMOS process and operates across a wide frequency range of 1–5 GHz (>4× better than prior works). Measurements resulted in +8.8 dBm in-band I P1dB, +23 dBm in-band IIP3, +9.3 dBm out-of-band (OOB) B1dB, +36 dBm OOB IIP3, +15 dB selectivity one bandwidth away, and +24 dB OOB rejection at far out frequencies.