Design of a 5-bit ADC 4Gs/s in 90-nm CMOS

A 5-b A/D converter (ADC) that converts at 2 GHz is reported. Using a wideband track-and-hold, a 5-b flash ADC achieves better than 4.4 effective bits for input frequencies up to 1.7 GHz at 4 Gsample/s, and 4.9 effective bits for 62.50-MHz input at 4 Gsample/s. Peak INL and DNL are less than 0.31 LSB and 0.4 LSB, respectively. This ADC consumes about 45 mW from 1.2 V at 4 Gsample/s. The A/D converter has been designed in 90nm CMOS technology