SC circuit for very large and accurate time constant integrators with low capacitance ratios

A switched capacitor active integrator which realises long time constant values with low capacitance ratios is presented. The basic circuit implements a parasitic-insensitive capacitive charge division, which allows for accurate control of the equivalent time constant. The offset of the operational amplifier is reduced via a correlated-double-sampling operation, and the effect of the finite gain of the operational amplifier is also reduced with respect to classic integrators when a modified topology is used