Analysis and Design of Flash Analog to Digital Converter for Ultra Wide Band Application

Abstract

Ultra-Wideband (UWB) communication is a recent high speed wireless technology that uses sub-nano second pulses to transmit information. According to United States Federal Communications Commission (FCC), a UWB technology is a form of wireless communication in which signals occupy a wide bandwidth, greater than the lesser of 500MHz or 20% of the center frequency of the signal is consider as an ultra wide band signal. A high speed low/medium resolution Analog-to-Digital converter (ADC) is required for processing the UWB signal. Considering latency and conversion speed, the flash ADC is often the most preferred selection in high-speed communication applications. Therefore, a 5-bit Flash ADC with 500Msamples/s sampling rates has been analyzed and designed. This 5-bit Flash ADC requires 31 comparators, resistor ladder of 32 resistors and thermometer-to-binary code converter (TC-to-BC). This ADC consumes 13.64mw from 1.8V supply voltage at 500MS/s with total conversion time of 1.135ns. The simulations of all the designs are done in cadence UMC 0.18um technology with a 1.8V power supply.