Design and Analysis of CMOS Telescopic Operational Amplifier

Abstract

We are witnessing the dominance of microelectronics (VLSI) in every sphere of electronics and communications forming the backbone of modern electronics industry in mobile communications, computers, state-of-art processors etc. All efforts eventually converge on decreasing the power consumption entailed by ever shrinking size of the circuits enabling the portable gadgets. Designing high – performance analog circuits is becoming increasingly challenging with the persistent trend towards reduced supply voltages .The main bottleneck in an analog circuit is the operational – amplifier. At large supply voltages, there is a trade – off among speed, power and gain. The main characteristics under consideration are high gain, high PSRR, low offset voltage, high output swing. Performance of any circuit depends upon these characteristics. At reduced supply voltages, output swing becomes an important parameter. Due to the consistent efforts the Op-amp architectures have evolved from a simple Two-Stage architecture to the high performance Telescopic amplifier involving less power consumption, low noise, high gain etc. The design procedure for a Single Stage Telescopic opamp is developed using design equations .The designed circuit is simulated using Tanner Tools. On the basis of simulation results the performance analysis has been done. The designed specifications are validated and the graphical analysis has been done. The simulated results are validating our designed values. The Telescopic op-amp has the inherent disadvantage of low output swing. A high-swing, high performance Single Stage CMOS Telescopic operational amplifier is analyzed and the results are presented in the form of design equations and procedure. The high swing of the op-amp is achieved by employing the tail and current source transistors in the deep linear region. Trade - off among such factors as bandwidth, Gain, Phase margin, bias voltages, output swing, slew rate, CMRR, PSRR, power are made evident. The results of SPICE simulation are shown to agree very well with the use of our design equations.