Novel minimum-component universal filter and quadrature oscillator with electronic tuning property based on CCCDBAs

The novel current-tunable voltage-mode universal biquad filter and sinusoidal quadrature oscillator using only two current-controlled current differencing buffered amplifiers (CCCDBAs) and two capacitors without external passive resistors have been presented. The first proposed filter realizes all the five standard types of the biquadratic functions and provides independent electronic tuning of the natural angular frequency (ωo) and the bandwidth (BW) through an external bias current of the CCCDBA. No critical component matching conditions are required. The second proposed oscillator generates two sinusoidal output voltages with 90° phase difference. Its oscillation condition and the oscillation frequency (ωo) are tunable independently through adjusting the bias current of the CCCDBA. Both the proposed circuit configurations have a low component count, attractive active and passive sensitivities and suitability to integrated circuit implementation. PSPICE simulation results that confirm the theoretical prediction, are also given and discussed.