An 8-b 100-MSample/s CMOS pipelined folding ADC

Abstract

Although cascading reduces the number of folders used in folding analog-to-digital converters (ADCs), it demands wider bandwidth. The pipelining scheme proposed in this work greatly alleviates the wide bandwidth requirement of the folding amplifier. The pipelining is implemented with simple differential-pair folders. The key idea is to use odd multiples of folders with distributed interstage track/holds cooperatively with an algorithm for coding and digital error correction for the nonbinary system. The pipelined folding ADC prototyped using 0.5-/spl mu/m CMOS exhibits a differential nonlinearity (DNL) of /spl plusmn/0.4 LSB and an integral nonlinearity (INL) of /spl plusmn/1.3 LSB at 100 MSample/s. The chip occupies 1.4 mm/spl times/1.2 mm in active area and consumes 165 mW at 5 V.