Unified Active Filter Biquad Structures

Unified Active Filter Biquad Structures Chun-Ming Chang, Bashir M. Al-Hashimi, and J. Neil Ross Electronics Systems Design Group Department of Electronics and Computer Science, University of Southampton, Highfield, Southampton SO17 1BJ, UK E-Mail:[email protected] Abstract: This paper presents one new biquad filter model based on nullators, norators, current mirrors and passive R (resistor) and C (capacitor) elements. Two implementations derived from the new biquad filter model by using second generation current-controlled conveyors (CCCIIs) and operational transconductance amplifiers (OTAs) are also proposed. The two biquad implementations are capable of achieving five important filter performance parameters simultaneously and without trade-offs, including universal filtering, minimum components count and independent control of ωo and ωo/Q. This is unlike recently reported filter structures which make certain trade-offs that emphasize some parameters at the cost of others. Simulation results are included confirming the theory prediction.