First-Order Mixed-Mode Universal Filter with Independent Gain Control Using CMOS-based active element DX-CCII

This paper introduces a novel mixed-mode electronically tunable multi-input multi-output (MIMO) first-order universal active filter (FO-UAF) that utilizes a single dual-X second-generation current conveyor (DXCCII), four resistors, and a grounded capacitor. By appropriately selecting the input signals, the circuit can achieve all three fundamental filter responses, namely Low Pass (LP), High Pass (HP), and All-Pass (AP), in all four feasible operating modes: Voltage mode (VM), Trans-admittance mode (TAM), Current mode (CM), and Trans-impedance mode (TIM), while utilizing the same circuit in which CM and TIM modes leveraging fully grounded passive components, making it highly advantageous for integrated circuit implementations. The notable feature of this proposed circuit is the independent tunability of gain (Ho) and Centre frequency (fo) across all modes of operation. In addition, the proposed circuit has been extended to function as a resistorless electronically tunable universal filter. Non-ideal analysis, stability of the circuit, and parasitic effects were performed on the proposed circuit. The proposed filter's performance was verified through PSPICE simulations using 0.18 µm CMOS technology, complemented by experimental validation with the commercially available analog IC AD844. A series of simulations, including Monte Carlo analysis, transient analysis, Lissajous pattern, total harmonic distortion (%THD) measurements, and temperature stability evaluations, were carried out thoroughly to evaluate the filters’ robustness and reliability under varying conditions. Also, the experimental results corroborate several simulation outcomes, demonstrating that the proposed configuration is highly suitable for practical applications.