Dual-Mode Tunable Q-Enhanced Filter for Narrowband and UWB Systems

Abstract

A dual-mode tunable Q-enhanced active filter is proposed and designed. The filter is capable of processing both 5 GHz narrowband (NB) and ultra wideband (UWB) services by switching mode dynamically. The design uses the mainstream 0.18 mum CMOS technology. In the UWB mode, the filter behaves as an LNA, however, when the NB interference is detected, the filter notches the NB frequency and provides gain for the UWB signals. Under this operation, the filter has an input matching of 10 dB, again of at least 5.6 dB, a narrowband rejection of 9.8 dB for a BW of 100 MHz and a 1 dB compression point of -15.1 dB. The filter performs better if it operates as a sole UWB LNA. In the NB mode, the filter is used for bandpass channel selection. It exhibits an input matching of 20.5 dB, a gain of 23 dB at 100 MHz BW, a noise figure of 7.1 dB and a 1 dB compression point of -26.8 dB. The circuit consumes less than 27 mW of power at 1.8 V supply. The design allows the same receiver front-end to provide both services while reducing system complexity and cost