Single Active Element Based Variable Gain Multifunction Filter with MOS-C Implementation

This paper introduces a new voltage-mode multifunction filter employing single current differencing transconductance amplifier (CDTA) and its MOS-C implementation. The proposed filter topology can synthesize all filter types, i.e. low-pass, high-pass, band-pass, band-stop and all-pass filters by modifying three admittances and gain of the filters can be adjusted independently by a resistor. Central frequency of the filters can be tuned electronically. The operability of the circuit is confirmed in close agreement with the theory by PSPICE simulation software using TSMC 0.18 micron CMOS model parameters at ±0.9 V supply voltage. The proposed circuit is suitable for integration technique through the MOS-C implementation.