Encoders for flash analog-to-digital converters

Analog-to-digital converters (ADC) are used in modern high-performance telecommunication systems. The fastest ADC is based on the flash architecture. The flash ADC speed is limited by two factors. The first one is the comparator response time in the input analog part of ADC. The second factor is the delay time of the encoder. The encoder converts the thermometer code into the straight binary code. In this paper, design of encoder circuits based on CMOS technology is considered. New encoder circuits with reduced delay are proposed. Comparative analysis of encoder main characteristics based on the circuit simulation is presented.