Design of low power and high speed multiplexer based Thermometer to Gray encoder

Abstract

This paper presents an improved multiplexer based encoder for flash analog-to-digital converters. The proposed encoder is designed using 2 : 1 multiplexers. This encoder can be configured to operate on thermometer-code with reduced resolution without any extra overhead. This encoder shows the re-configurable property i.e. higher resolution encoder can be configured as lower resolution encoder. This self re-configurable property can be used in adaptive resolution flash ADCs. Gray codes are mainly used in glitch free fast circuit design and in communication for error correction in digital modulation techniques. Simulation results indicate that power, delay and figure of merit of this encoder is less than the existing digital encoders. The encoder is designed in CMOS BSIM4 90nm technology and 1.2V power supply. The power consumption is 69μW with 7.375ns delay and 511.58fJ figure of merit using 1.2V power supply for 5 bit flash ADC.