A Low-Power 9-bit Pipelined CMOS ADC with Amplifier and Comparator Sharing Technique

Abstract

This paper describes a pipelined analog-to-digital converter (ADC) employing a power and area efficient architecture. The adjacent stages of a pipeline share operational amplifiers. In order to keep accuracy of the amplifiers in the first stages, they use a partially sharing technique. The feature of the proposed scheme is that it also shares the comparators. The capacitors of the first stages of a pipeline are scaled down along a pipeline for a further reducing the chip area and its power consumption. A 9-bit 20-MSamples/s ADC, intended for use in multi-channel mixed-signal chips, has been fabricated via Europractice in a 180-nm CMOS process from UMC. The prototype ADC shows a spurious-free dynamic range of 58.5 dB at a sample rate of 20 MSamples/s, when a 400 kHz input signal with a swing of 1 dB below full scale is applied. The effective number of bits is 8.0 at the same conditions. ADC occupies an active area of 0.4 mm2 and dissipates 8.6 mW at a 1.8 V supply.