Improved current-mode wave active filter

Abstract

ABSTRACT In this paper, a resistorless improved wave active filter (WAF) is presented using a comparatively new current-mode building block, namely extra X current-controlled current conveyor (EX-CCCII). The proposed wave active filter is designed in the current mode. The incident and reflected waves are used for designing the basic wave active elements, namely series and shunt inductors (L) and capacitors (C). The novelty of the circuit is that the mathematical operations like lossy integrator, unity gain amplifier, summation, and subtraction, required to realise the wave active elements, are accomplished by judiciously using the port relationships of EXCCCII. As a result of which the proposed circuit is compact and uses only two EXCCCIIs and one grounded capacitor for the realisation of wave elements (L and C). One 3rd and one 4th order Butterworth wave active filters are designed using EX-CCCII-based wave elements and simulated in cadence using 0.18 µm TSMC CMOS technology. The comparison indicates that the proposed WAF uses minimum numbers of analog building blocks (ABBs) and consumes the least power; moreover, the performances such as noise, percentage total harmonic distortion (%THD), and electronic controllability of cut-off frequency of the filters are also reported. Abbreviations: ABB: analog building block; FDNR: frequency-dependent negative resister; WAF: wave active filter; THD: total harmonic distortion; OTA: operational transconductance amplifier; CFOA: current feedback operational amplifier; VDTA: voltage differencing transconductance amplifier; OTRA: operational transresistance amplifier; CCDDCCTA: current-controlled differential difference current conveyor transconductance amplifier; DVCCCTA: differential voltage current-controlled conveyor transconductance amplifier; DVCCTA: differential voltage current conveyor transconductance amplifier; EX-CCCII: extra X current-controlled conveyor