Voltage-Mode Universal Biquadratic Filter Using Tunable OTA in 180nm Technology
Smaranika Sahoo · International Journal for Research in Applied Science and Engineering Technology · 2017
Conventional Operational Amplifiers (Op-Amps) limit their applications at high frequencies. Since output is a voltage, Op-Amps limit to frequencies up to few Megahertz. At those high frequencies, Operational Transconductance Amplifiers (OTAs) are being promising to replace Op-Amps as building blocks. OTAs are useful in realisation of active Gm-C filters. A Balanced OTA which is the simplest configuration of an Operational TransconductanceAmplifier is chosen as a basic building block for the present work.The resulting OTA has improvement as compared to the basic balanced OTA in terms of better gain, CMRR and slew rate.Further, the improved circuit of balanced OTA is used to implement tunable OTA.The Tunable OTA designed in the present work has gain 55.48dB, Common Mode Rejection Ratio (CMRR) of 133.775dB,Slew rate of 45.67V/μs.A Bi-Quad Filter is implemented using Tunable OTA as an application example.A Low pass, High pass, Band pass, Band Reject and All pass filters are demonstrated by controlling the input control voltages.The circuits are implemented in gpdk180 in Cadence software.