A NOVEL CURRENT-MODE ACTIVE-R BIQUAD USING DIFFERENTIAL-INPUT DIFFERENTIAL-OUTPUT OPERATIONAL-AMPLIFIERS

This paper introduces a novel current-mode active-Ii biquadratic circu it employing two differential-input differential-output operational am plifiers (DIDO OAs). The circuit configuration has been obtained utili zing Soderstrand's voltage-mode state variable filter as a prototype. It is shown that the proposed circuit can realize five different biqua dratic transfer functions simultaneously without changing the circuit topology. The parasitic effects of DIDO OAs on the circuit characteris tics are also discussed using a general model of OA gain. An example i s given together with simulated results by PSpice.