Journal Article

Electronically Tunable First Order AP/LP and LP/HP Filter Topologies Using Electronically Controllable Second Generation Voltage Conveyor (CVCII)

Stornelli, Vincenzo, Barile, Gianluca, Ferri, Giuseppe, Safari, Leila, Pantoli, Leonardo

2021

Overview

In this paper two new first order filter topologies realizing low-pass/all-pass (LP/AP) and low-pass/high-pass (LP/HP) outputs using electronically controllable second generation voltage conveyors (CVCIIs) are presented. Unlike second generation voltage conveyors (VCII), in CVCII each performance parameter, including ports, parasitic impedances, current and/or voltage gains can be electronically varied. Here, in particular, the proposed filter topologies are based on two CVCIIs, one resistor and one capacitor. In the first topology VLP/IAP/VAP and in the second topology ILP/VLP/IHP/VHP outputs are achievable, respectively. However, the current and voltage outputs are not achievable simultaneously and a floating capacitor is used. A control current (Icon) is used to change the first CVCII Y port impedance, which sets the filter −3 dB frequency (f0) of all the outputs. Moreover, in the second topology, the gains of HP and AP outputs are electronically adjusted by means of a control voltage (Vcon). Favorably, no restricting matching condition is necessary. PSpice simulations using 0.18 µm CMOS technology and supply voltages of ±0.9V show that by changing Icon from 0.5 µA to 50 µA, f0 is varied from 89 kHz to 1 MHz. Similarly, for a Vcon variation from −0.9 V to 0.185 V, the gains of IAP and IHP vary from 30 dB to 0 dB and those of VAP and VHP vary from 100 dB to 20 dB. The total harmonic distortion (THD) is about 8%. The power consumption is from 0.385 mW to 1.057 mW.

• Publisher: MDPI AG
• Subject: Capacitors / CMOS / Conveyors / Electric potential / Harmonic distortion / Low pass filters / Power consumption / Signal processing / Stability / Topology / Voltage