RF Reconfigurable Filter

Abstract

In this paper, a fully differential noise-cancelling LNA (Low Noise Amplifier) with out-of-band rejection notch filter combined with a programmable gain-boost N-path bandpass filter is proposed. The wide-band noise-cancelling LNA is at the first stage for the noise dominant and input matching while the notch filter is rejecting the out-of-band signal, followed by gain-boost N-path bandpass filter for further gain improvement and frequency selection. The center frequency is determined by the switching frequency of the N-path filter, while the RC-time constant defines the bandwidth. Mostly the high-Q filter can be achieved by the frequency selection.