Design of Analog to Digital Converter Using CMOS Logic

Abstract

The real world signals are all analog in nature. The digital signals and digital circuits offer greater advantages as compared to analog circuits in processing speed and efficient transmitting. So in order to convert the analog signals to digital efficiently an “Analog to digital converter” is required. The System on Chip (SoC) forces the analog circuits to be integrated with digital circuits. To follow the scaling down of the SoC trend, analog to digital converter should be operated at low voltages. Thus the idea behind the paper is to design a 3-bit flash ADC using Threshold Inverter Quantization technique with 130nm CMOS technology for high speed and low voltage applications. Threshold Inverter Quantization (TIQ) is a unique way to generate a comparator for a high speed CMOS flash ADC. To improve further, the fat tree encoder that is highly suitable for the ultrahigh speed flash ADCs. A fat tree encoder that has signal delay of “0” is used for better performance. The speed is improved by almost a factor of 2 when using the fat tree encoder. The fat tree encoder is an effective solution for the bottleneck problem in ultra-high speed ADCs. The proposed A/D converter is suitable for System on Chip (SoC) applications in wireless products and other ultra high speed applications.