Optimisation of parasitic insensitive switched capacitor biquads

A powerful technique is described for the optimisation of parasitic insensitive switched capacitor (SC) biquads. The proposed method minimises the total capacitance and the component spread necessary for realising a 2nd-order transfer function by a parasitic insensitive SC network. The increase in the network insensitivities due to the minimisation of the total capacitance is controlled by multiple criteria optimisation techniques. The method allows the optimisation to be performed with a variable network topology without, however, requiring large computational times. The number of components in the final network is limited and the dynamic range of the filter is also controlled. An example is given which demonstrates the possibility of considerable design improvement by using the proposed technique.