A Low-Power Complex Active-RC Filter for Low-IF Receivers Using a New Class-AB Operational Amplifier

The design of a complex active-RC filter for low-IF wireless applications is described. Fifth-order complex Butterworth filter is designed using class-AB operational amplifier architecture. This new structure makes the filter suitable for low power applications with high dynamic range. Simulation results show that the filter provides more than 40 dB image rejection ratio (IIR) and dynamic range of 82 dB. The complete filter including on-chip tuning circuit consumes only 4.3 mW with 1.8 V single supply voltage.