Passive coupled-switched-capacitor-resonator-based reconfigurable RF front-end filters and duplexers

Abstract

High-Q resonators may be used to synthesize selective bandpass filters. Many commercial radio-frequency filters are based on coupled-resonators and realized in surface and bulk acoustic wave technologies due to the high quality factor and compact size of acoustic resonators. In this paper, it is shown that discrete-time equivalent of coupled-resonator bandpass filters may be realized using passive switched-capacitor circuits. The center frequency and the bandwidth are determined by the frequency of the switch driving signals and the capacitor values. The proposed passive filters can be linear, low noise, and compact. To further enhance the in-band linearity, an RF bootstrapping technique is proposed. Design and experimental verification of a forth-order RF BPF and a duplexer, realized in a 65nm CMOS technology, are reported.