High-Input Impedance Four-Input One-Output Voltage-Mode Universal Filter Using OTAs

This paper presents a new electronically tunable voltage-mode universal filter with four-input one-output using six single-ended operational transconductance amplifiers, two grounded capacitors and two MOS resistors. The proposed circuit can realize of lowpass, bandpass, highpass, bandstop and allpass filters, without component-matching conditions and inverting input signals requirements. The natural frequency and the quality factor can be tuned orthogonally and electronically by adjusting the bias currents. The filter offers the features of high input impedances, low active and passive sensitivities and use of grounded passive components which is ideal for integrated circuit implementation. The workability of the proposed circuit is confirmed using PSPICE simulators.