Progress In Science and Engineering Research Journal ISSN 2347-6680 (E) © 2014 PISER Journal http://.piserjournal.org/ PISER 15, Vol.02, Issue: 05/06 September-October; Bimonthly International Journal Page(s) 165-168 DESIGN OF LOW-VOLTAGE, HIGH-GAIN OPERATIONAL AMPLIFIER FOR DATA CONVERTERS E. Srinivas 1 , Dr. N. Balaji 2 , Dr. L. Padma Sree 3 1 Research scholar, 2,3 Professor, Department of ECE 1 JNTU Hyderabad, 2 JNTU Vizayanagaram, 3 VNR VJIET, Hyderabad Abstract: The objective of this paper is to design a low- voltage,high gain operational amplifier used in data converters.These data converters are used in telecommunication, signal processing and biomedical applications.This work presents the optimized architecture of an operational amplifier.The simulation results are verified by using 0.18μm CMOS technology at supply voltage 1.8v. Index Terms: CMOS analog circuit, Operational Amplifier, Low-voltage, High-Gain. I. INTRODUCTION Over the last few years, the electronics industry has exploded. The largest segment of total worldwide sales is dominated by the MOS market. Composed primarily of memory, micro and logic sales, the total combined MOS revenue contributed approx 75% of total worldwide sales, illustrating the strength of CMOS technology. CMOS technology continues to mature with minimum feature sizes now. Due to relatively simple circuit configurations and flexibility of design, CMOS technology has an edge over NMOS technology and is gaining rapid acceptance as the future technology for linear analog integrated circuits, especially in the communication field, biomedical and signal processing applications. Corresponding Author: 1. Mr. E. Srinivas, Research scholar, JNTU, Hyderabad Email Id: edem.srinivas@gmail.com 2. Dr. N. Balaji, Professor, Department of ECE, JNTU, Vizayanagaram Email Id: narayanamb@rediffmail.com 3. Dr. L. Padma Sree, Department of ECE VNR VJIET, Hyderabad Email Id: l-padmasree@vnrvjiet.in Operational amplifiers (usually referred to as OPAMPs) are key elements in analog processing systems. OPAMP can be said to be the main bottleneck in an analog circuit. Ideally they perform the function of a voltage controlled current source, with an infinite voltage gain. Operational amplifiers are an integral part of many analog and mixed-signal systems. OPAMPs with vastly different levels of complexity are used to comprehend functions ranging from dc bias generation to high-speed amplification or filtering. The design of OPAMPs continues to pose a challenge as the supply voltage and transistor channel lengths scale down with each generation of CMOS technologies. Designing high-performance analog integrated circuits is becoming increasingly exigent with the relentless trend toward reduced supply voltages. At large supply voltages, there is a tradeoff among speed, power, and gain, amid other performance parameters. Often these parameters present contradictory choices for the op- amp architecture. Speed and accuracy are two most important properties of analog circuits, however optimizing circuits for both aspects leads to contradictory demands. The realization of a CMOS OPAMP that combines a considerable dc gain with high unity gain frequency has been a difficult problem. There have been several circuit approaches to evade this problem [1]. The design of operational amplifiers puts new challenges in low power applications with reduced channel length devices. In the design fully differential topology has been employed for high gain and high bandwidth applications. In order to obtain an input stage with a rail-to-rail input range, an n- and p-