Design and Implementation of CMOS Telescopic Op-Amp for Bio-Medical Applications

K Shashidhar (Guru Nanak Institutions Technical Campus (Autonomous), Hyderabad, United Kingdom (Great Britain)); Sreenivasa Ijjada (GITAM University, Visakhapatnam, India)

Operational Amplifiers (Op-Amps) are the basic integral part of all analog VLSI designs and mixed VLSI designs. For bio-medical applications, the Op-Amp with higher common mode voltage and low noise is essential to evaluate qualitatively the electrocardiogram (ECG) signal and electroencephalography (EEG) signal in the diagnosis process for more accurate treatment of patients. Medical instruments with qualitative signals help the doctors to efficiently reduce the time in the diagnosis process. Generally folded cascode Op-Amp find uses in many of the applications, but it has heavy current consumption to achieve the required transconductance (gm), it is noisier and consumes more power. There is a need for an Op-Amp with less power, less noise and more gm. Folded cascode Op-Amp can be replaced with telescopic Op-Amp at the output stage to enhance the common mode input voltage. Telescopic circuits require half of the supply current as that of folded cascode circuit to obtain the same amount of peak current output and transconductance, with much reduced noise in telescopic Op-Amp. As this configuration takes lower currents, the speed of operation increases. Our work reported here concentrates on the design of higher gain and high slew rate Op-Amp, which would be able to measure bio-medical signals like ECG, EEG etc with higher clarity. The Op-amp is able to produce a gain of 81dB, Phase Margin greater than 450, improved Unity Gain Bandwidth (UGB) of 4.03MHz, with a power less than 190μW. The design can be implemented with 0.18μm CMOS technology with 1.8V power supply. The cadence virtuoso tools were used for this design.

Journal: International Journal of Simulation- Systems, Science and Technology- IJSSST V20

Published: Feb 27, 2019

DOI: 10.5013/IJSSST.a.20.01.31