Gain- and offset-compensated switched-capacitor filters

Novel gain- and offset-compensated (GOC) switched-capacitor bilinear and biquadratic sections using a two-phase clock are presented. Theoretical analysis and simulation results show that the frequency responses of these circuits have very low sensitivity to the finite operational amplifier (op-amp) gain, while the time responses are insensitive to nonzero op-amp input offset voltages. Very large time-constant GOC bilinear and biquadratic sections using T-capacitive cells as voltage dividers are also described. As an example, an eighth-order Bessel-Chebyshev lowpass filter with a very low cutoff frequency is described. Simulation results of the new and the conventional designs are presented and compared.