Finite gain compensated double-sampled switched-capacitor integrators for high-Q bandpass filters

摘要

A technique for the compensation of the operational amplifier (op-amp) finite gain error in the switched-capacitor (SC) integrator is proposed. Two possible SC integrators implementing the proposed technique are given. Both implementations allow the use of the double-sampling technique to increase by a factor of two the maximum speed of operation. The compensation operation consists in memorizing a sequence of output values of the SC integrator, and using them in the proper clock period to compensate the error due to the nonideal virtual ground. The compensation is mostly effective in a narrow frequency range centered around one specific frequency. The circuits implementing this technique are therefore particularly useful for high-Q high-frequency bandpass filters. The case of a biquadratic bandpass filter is reported as an example.