Voltage-Mode Multifunction Biquadratic Filter and Sinusoidal Oscillator Using Only Two CDBAs
In this paper, the voltage-mode multifunction biquadratic filter and oscillator employing current differencing buffered amplifiers (CDBAs) as active components are proposed. Both proposed configurations are mainly composed of two CDBAs and six passive components. The first proposed CDBA-based configuration can realize lowpass, bandpass, highpass, bandstop and allpass biquadratic filter functions, and provides orthogonal adjustment of the natural angular frequency (wo) and the bandwidth (BW) through separate virtually grounded passive components. By slight modification of the first proposed configuration, the new CDBA-based sinusoidal oscillator is obtained. The oscillation condition and the oscillation frequency are independently controllable by different resistors. The active and passive sensitivities of all proposed circuits are shown to be low. Simulation results based upon commercially available AD844-type CFAs are included, which confirm the workability of the proposed circuit configurations.
Keywords: Current Differencing Buffered Amplifier (CDBA), voltage-mode circuit, universal filter, oscillator.