The voltage-mode universal biquadratic filter and sinusoidal quadrature oscillator based on the use of current differencing buffered amplifiers (CDBAs) as active components have been proposed in this paper. All the proposed configurations employ only two CDBAs and six passive components. The first proposed CDBA-based biquad configuration can realize all the standard types of the biquadratic functions, that is, lowpass, bandpass, highpass, bandstop, and allpass, from the same topology, and can also provide orthogonal tuning of the natural angular frequency(ωo)and the bandwidth (BW) through separate virtually grounded passive components. By slight modification of the first proposed configuration, the new CDBA-based sinusoidal quadrature oscillator is easily obtained. The oscillation condition and the oscillation frequency are independently adjustable by different virtually grounded resistors. The sensitivity analysis of all proposed circuit configurations is shown to be low. PSPICE simulations and experimental results based upon commercially available AD844-type CFAs are included, which confirm the workability of the proposed circuits.

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This paper describes the practical realization of electronically adjustable voltage-mode universal filter with three inputs and single output (TISO) using the commercially available integrated circuit (IC)-based voltage differencing buffered amplifiers (VDBAs). The realization is resistor-less and contains only two VDBAs and two capacitors. The described filter structure can realize all the five standard biquadratic filter functions from the same configuration without needing any component matching criterions. It also exhibits low-output impedance, which enables for easy cascading in voltage-mode operation. Owing to practical VDBA realization, the filter circuit can be easily made electronically tunable with orthogonal o-Q tuning. The effects of the VDBA non-idealities on the filter performance have been analyzed in detail. To prove the theoretical finding, the performance of the studied circuit was also experimentally measured using the operational transconductance amplifier