VDBA-Based Electronically Tunable Capacitance Multiplier with a Grounded Capacitor

This work presents an electronically tunable grounded capacitance multiplier circuit based on the voltage differencing buffered amplifier (VDBA), a recently introduced active building block. The proposed capacitor circuit requires only two VDBAs, one floating resistor, and one grounded capacitor. The circuit can be tuned electronically via the VDBA transconductance ratio. The effect of the VDBA non-idealities on the simulated capacitance value has also been discussed in detail. The usability of the proposed tunable capacitance simulator has been verified by realizing the fourth-order low-pass filter application with a Butterworth approximation. In order to verify the theory, the behavior of the circuits is evaluated with PSPICE simulation program using TSMC 0.25 mu m CMOS process parameters.