A 150 Msample/s 20 mW BiCMOS switched-capacitor biquad using precise gain op amps

This paper presents a design approach to realize high-frequency IIR SC filters. The trade-off between speed-and-gain in the design of the op amps is overcome by designing a simple and compact amplifier with a limited but precisely controlled gain. The finite gain effect is taken into account in the filter design by adjusting the capacitor ratio. In addition the filter uses nMOS-only switches therefore requiring a standard two-phase clock. Finally the clock-to-bandwidth ratio is equal to 10, so a fairly non-critical anti-aliasing filter is needed.