CMOS transconductance amplifiers, architectures and active filters: a tutorial

An updated version of a tutorial paper (see IEEE Circuits Devices Mag., vol. 2, no. 1, p. 20-32, 1985) on active filters using operational transconductance amplifiers (OTAs) is presented. The integrated circuit issues involved in active filters (using CMOS transconductance amplifiers) and the progress in this field in the last 15 years is addressed. CMOS transconductance amplifiers, nonlinearized and linearized, as well as frequency limitations and dynamic range considerations are reviewed. OTA-C filter architectures, current-mode filters, and other potential applications of transconductance amplifiers are discussed