Fully differential CMOS sigma-delta modulator for high performance analog-to-digital conversion with 5 V operating voltage

摘要

The authors present a high-performance second-order sigma-delta modulator for modem and ISDN (integrated-services digital network) analog-to-digital (A/D) conversion applications. The major performance design limiting factors are demonstrated. It is shown that a true 16-bit A/D converter with single 5-V power supply for voice band can be realized with an oversampling ratio of 512; and a 16-bit dynamic range is achieved with an oversampling ratio of 256. The die size of the proposed modulator, using 2.5- mu m CMOS technology, is only 0.56 mm/sup 2/.