Switched-capacitor high-Q bandpass filters for IF applications

Experimental results for a sixth-order switched-capacitor bandpass filter with a selectivity Q of 55 at a center frequency of 3.1 MHz are presented. A simple noise analysis of active bandpass filters composed of coupled identical resonators is introduced to explain the dynamic range reduction in high-Q active filters resulting from loose high-Q couplings between resonators. Theoretical predictions of noise in coupled resonator-type bandpass filters agree well with measured results. The prototype chip occupies 2 mm/SUP 2/ and dissipates 45 mW with a single 5-V supply.