Voltage-Mode First-order Multifunction Filter with Electronic Controllability Using VDDDA

Abstract

This study presents the design of a three-input single-output voltage-mode first-order multifunction filter. The proposed filter comprises a single VDDDA as the active component, one grounded capacitor, and two resistors. The output voltage node has low impedance. The proposed filter provides three responses consisting of a low-pass (LP), a highpass (HP), and an all-pass (AP) by setting the voltage signal at the input voltage. The natural frequency ($f_{0}$) and phase response are electronically controlled by the bias current ($I_{B}$). This flexibility allows for precise tuning of the filter characteristics to meet specific application requirements. The passband gain of LP and HP filters can be adjusted using resistors $\boldsymbol{R}_{1}$ and $\boldsymbol{R}_{2}$ without affecting the $f_{0}$ or requiring an additional amplifier. The simulation and experimental results validate the functionality of the proposed filter as anticipated theoretically. This reliability is crucial for communications and signal processing applications, where accurate signal representation is paramount.