The principle of equivalence between switched-capacitor (SC) and switched-current (SI) circuits is described. A new SI biquadratic filter is presented with this equivalence. The SI circuit is derived from the SC biquadratic prototype with three op amps in literature[5]. The important feature of the proposed SI circuit is that it can simultaneously obtain lowpass
bandpass and highpass filter outputs
in a single building block. A general biquadratic realization is also proposed with this SI circuit.