Design & Simulation Of Wide Swing Folded Cascode OTA Using 0.35 ΜM CMOS Technology

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. 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 Telescopic amplifier involving less power consumption, low noise, but Telescopic amplifier has the inherent disadvantage of low output Swing. Cascode circuits are widely used in circuit design at places where high gain and high output impedances are required. “Folded Cascode Operational Tranconductance Amplifier” topology is done in order to optimize MOS transistor sizing. Cascode circuits are widely used in circuit design at places where High gain and High output impedances are required. Amongst all the topologies of OTA, Folded Cascode OTA is chosen as it allows shorting of input and output terminals with negligible swing limitations. The design of folded cascode OTA, which works for RF application. “Wide-swing Folded Cascode OTA” which extends the input CMR beyond the power supply rails by combining both the NMOS and PMOS input pairs differential amplifiers. Filters are the indispensable parts of any communication systems. There are various methods to design a filter depending upon the specifications and the application. Filter design using OTA is the most common method. Programmable high-frequency active filters can be achieved by incorporating the operational Transconductance Amplifier-Capacitor filters (OTA-C). OTA-C filters also have simple structures, and can operate up to several hundreds of MHz. Also the OTA-C filters become very Power hungry at GHz range. OTA-C filter has been designed by replacing all the passive components in a passive network with an active device. “Wide Swing Folded cascode OTA” is selected as it suits best. Programmable highfrequency active filters can be achieved by incorporating the operational Transconductance Amplifier-Capacitor filters (OTA-C). All Simulation results are performed using SPICE software and BSIM3V3 model for CMOS 0.35μm process.