Performance optimization of elliptic SC ladder filters using signal-flow graph transformations

Switched-capacitor filters are derived from doubly-terminated LC networks using signal-flow graph techniques. Conventionally, one SC circuit is obtained from the prototype network. A class of signal-flow graph transformations that allow a whole family of equivalent circuits to be generated for a given transfer function is proposed. The resulting circuits feature low sensitivity to capacitor mismatch. It is shown by a numerical example that other parameters, notably capacitance spread and signal-to-noise ratio, can be significantly improved by the proposed transformations