Tunable High-Q N-Path Band-Pass Filters Modeling and V erification Amir Ghaffari

Abstract

A differential single-port switched-RC N-path filter with band-pass characteristic is proposed. The switching fre- quency de fines the center frequency, while the RC-time and duty cycle of the clock de fine the bandwidth. This allows for high-Q highly tunable filters which can for instance be useful for cognitive radio. Using a linear periodically time-variant (LPTV) model, exact expressions for the filter transfer function are derived. The behavior of the circuit includin g non-idealities such as ma