Design and Characterization of ADC using FinFETs for low power applications

Abstract

In this research work the focus is on design of sub systems of ADC which is carried out by designing operational amplifier as one of the sub modules. Operational amplifier circuit is designed using model parameters of high-k FinFET in 22nm technology. The conventional design expressions for MOSFET based OPAMP design are fine tuned to design FinFET based OPAMP. The OPAMP design is suitable for use as sub circuit in ADC design as it supports low voltage, high speed, and low power dissipation. The transistor geometries are identified so as to achieve high and energy efficient OPAMP. Schematic capture is carried out using Cadence tool. For the designed OPAMP newlineoperating at 10 GHz, power dissipation is estimated to be 12 µw. OPAMP has a UGB of 100 GHz and the comparator circuit UGB is 5 GHz which is used for the design of ADC. newlineOTA based circuits are gaining importance in analog circuit applications such as filters, newlineconverters, and oscillators. The use of FinFET based OTA exhibits better performance in newlinecomparison to conventional CMOS based OTA. Design of OTA requires estimating the W/L newlinegeometries of transistors to meet performances such as DC gain, Unity-Gain Bandwidth (UGB), Common Mode Rejection Ratio (CMRR), Slew Rate (SR), Input common-mode voltage (VICM) and Power dissipation. Comparator that forms the sub block of most of the analog circuits is designed using Operational Trans-conductance Amplifier (OTA). In this work, comparator circuit which forms the sub system in every data converter circuit is designed using OTA from basic principles and is evaluated for its performances to operate at high frequencies. The OTA is designed using new design procedures and the comparator circuit is designed integrating the sub circuits with OTA. The building blocks of the comparator design such as input level shifter, differential pair with cascode stage and class AB amplifier for output swing are designed and integrated.