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

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-mum CMOS exhibits a differential nonlinearity (DNL) of +/-0.4 LSB and an integral nonlinearity (INL) of +/-1.3 LSB at 100 MSample/s, The chip occupies 1.4 mm x 1.2 mm in active area and consumes 165 mW at 5 V.