A novel ultra high speed reconfigurable switching encoder for Flash ADC

In Flash ADC designs, the speed of thermometer code to binary code encoder often becomes the bottleneck in achieving ultra high speed. This necessitates new design for encoder which can operate accurately at multi Giga hertz range. In this paper, a unique encoder design technique is presented which exploits the signal pattern in thermometer code and generates corresponding binary bits using lower resolution encoder. The circuit is designed in CMOS 90nm technology. The cadence simulation results prove that the switching encoder is the fastest encoder which can operate at 16GHz and is more efficient in terms of power dissipation as it consumes only 46μW at 1.2V supply voltage. The switching encoder can be easily reconfigured for higher resolution ADC by merely multiplexing the inputs which makes this encoder versatile. These encoders find application in the design of high speed flash ADCs.