Analysis and Design of Two-Port $N$- Path Bandpass Filters With Embedded Phase Shifting

N-path switched- RC circuits are a promising solution for realizing tunable high- Q filters on chip. Here, a novel method of embedding phase-shifting functionality into the two-port N- path filter response by shifting the phase of the input and output clock sets relative to each other is introduced. Furthermore, a two-port design allows us to embed variable attenuation that can be useful in applications such as wideband self-interference cancellers and phased-array front ends, where filtering, phase shifting, and variable gain are functionally required. The effect of the embedded phase shift is analyzed with linear periodically time-variant theory and has been verified through simulations and measurement. Measurement results are presented for a two-port N- path filter implemented in a 65-nm CMOS 0.8-1.4-GHz highly reconfigurable self-interference canceling receiver. The two-port filter achieves 13-dB gain control and full 360° phase-shift range for the in-band transfer function.