Electronically tunable CFTA based positive and negative grounded capacitance multipliers

This paper presents four novel lossless grounded capacitance multiplier (GCM) circuits based on Current Follower Transconductance Amplifier (CFTA). Two of the proposed GCMs are positive and two are negative. The proposed GCMs include two CFTAs, two resistors, and a capacitor. The proposed GCMs employ a minimum number of passive components and do not require any passive element matching condition. The multiplication factor can be controlled either by bias current or by varying either of the two resistances. The effects of parasitic elements on the operating frequency range of the proposed GCMs have been investigated through mathematical analysis. Time and frequency domain analysis has been performed with LTspice program using 0.13 µm IBM CMOS technology parameters. The capacitance cancellation circuit and current-mode universal biquad filter applications are provided to demonstrate the usefulness of the circuit. Monte Carlo and temperature analyses have been performed to verify the robustness of the proposed GCMs. Additionally, comparison of the proposed GCMs with the relevant circuits previously reported in the literature is presented. An experimental example is provided to verify the time-domain performance of the proposed positive lossless GCM by using commercially available integrated circuits (ICs).