A Fully-Differential Class-AB Switched-Current Integrator for Filters and ΣΔ-Modulators

A class-AB switched-current integrator is designed with a 1.2 μm CMOS-process which uses a fully differential and complementary topology. With the designed integrator a fast fully-differential 6th order switched-current ladder filter with transmission zeros and a second order fully-differential switched-current ΣΔ-modulator is realized. The low-pass cut-off frequency of the filter is 1 MHz and it has a transmission zeros at approx. 1.5 MHz. Both designed circuits have a 15 MHz clock. Both chips include a differential voltage-to-current converter and the filter also has an output current-to-voltage converter.