A 12.8-MHz sigma-delta modulator with 16-bit performance

Abstract

The authors describe a CMOS second-order Σ-Δ modulator that does not require error correction or component trimming to achieve virtually ideal 16-b performance at a conversion rate of 50 kHz. This modulator is a fully differential circuit that operates from a single 5-V power supply and does not require the use of precision sample-and-hold circuitry. With an oversampling ratio of 256 and a clock rate of 12.8 MHz, an experimental implementation of the modulator achieves a 98-dB dynamic range and 94-dB linearity. The nearly ideal 16-b performance of the modulator and its small area of 0.39 mm2 and power dissipation of only 13.8 mW make it suitable for use as a digital-audio quality analog interface within digital signal processing chips and systems