BiCMOS Switched-Capacitor Linear-Phase Bandpass Filter for RDS applications

The design of an 8th order switched-capacitor bandpass filter centered at 57kHz with 3kHz bandwidth and linear phase characteristics in the passband is reported. Four biquads are cascaded and operated at 4.332 MHz with double-sampling technique. The group delay performance have been analyzed via Monte Carlo simulations: there results an expected mean value of 230 μs with 2.9 μs standard deviation, using a unit capacitor statistic with 0.15% relative standard deviation. The filter is a basic circuit for an RDS integrated decoder and is realized in high performance BiCMOS technology.