New Approach to Design Resistorless Electronically Tunable Grounded Capacitance Multipliers Using CMOS VDIBAs

Capacitance multipliers are essential in applications requiring large capacitance but constrained by size, cost, or integration feasibility. Their ability to simulate high-value capacitors using active components makes them crucial in modern ICs, power electronics, biomedical devices, wireless communication, and sensor interfaces. This paper presents a novel approach for designing resistorless grounded capacitance multiplier (GCM) circuits. The proposed design employs the voltage differencing inverting buffered amplifier (VDIBA) as the active block, leading to the introduction of 18 new GCM circuits. These circuits utilize two VDIBAs and a single capacitor, enabling both positive and negative capacitance multiplication factors (MFs). The MF of all the presented circuits can be electronically tuned using bias voltages and also have independent control. The design eliminates stringent matching constraints, enhancing practical feasibility. Furthermore, the impact of nonideal VDIBA parasitics on circuit performance is thoroughly analyzed and compared with ideal values. To validate the proposed approach, the circuits are applied in the design of a first-order low-pass filter (LPF). Their functionality is further confirmed through a CMOS-based VDIBA implementation using 0.18 μm TSMC technology parameters in PSPICE simulations. Comprehensive analyses, including frequency and transient response, Monte Carlo analysis, process corner evaluation, and temperature variation, demonstrate the robustness of the circuits. The proposed GCM circuits operate over a wide frequency range from 1 mHz to 0.1 GHz, making them suitable for applications such as signal processing, impedance matching, and noise filtering. The capacitance can be enhanced up to 20 times its original value, while the circuit consumes approximately 1.5 mW of power. Experimental frequency response of an application example of a LPF using a VDIBA, implemented with commercially available ICs CA3080 and AD830, is also provided.