Design of low-power switched-capacitor filter with switched-opamp technique

The modified switched-capacitor biquad circuits for low-Q and high-Q structures are presented in This work. By using the switched-opamp technique, the structures make only one active opamp in each phase without destroying their biquad functions. This idea can be applied on the implementation of high-order SC filters to save more power consumption. Meanwhile, the z-domain transfer functions for SC biquad circuits are analyzed to verify the modified structures. Finally, three types of low-Q SC biquad filters are presented as design examples. The simulation results show that the frequency responses of the general active-RC biquad circuits and the modified SC ones are much similar.