Single CDBA Based-Universal Biquad with Feedback Topology

摘要

A voltage-mode single input-single output type universal biquad is proposed. It uses only one current difference buffered amplifier (CDBA) as the active element and contains grounded and virtually grounded capacitors. Using this biquad, one may realize all five filter functions (i.e., low-pass, high-pass, band-pass, notch and all-pass) without changing the circuit topology. Since the output of filter exhibits low output impedance, it can be directly cascaded without additional buffers. Also its Q-factor can be independently adjusted if the naturel frequency is fixed. Moreover, biquad offers low sensitivities, and its naturel frequency is insensitive to tracking errors. Finally, theoretical results are verified with PSPICE simulations using CMOS realization of CDBA.