A NYQUIST-RATE DELTA-SIGMA A D CONVERTER

This paper describes an analog-to-digital converter which combines mul tiple delta-sigma modulators in parallel so that time oversampling may be reduced or even eliminated, By doubling the number of Lth-order de lta-sigma modulators, the resolution of this architecture is increased by approximately L bits, Thus, the resolution obtained by combining n d delta-sigma modulators in parallel with no oversampling is similar t o operating the same modulator with an oversampling rate of M. A paral lel delta-sigma A/D converter implementation composed of two, four, an d eight second-order delta-sigma modulators is described that does not require oversampling, Using this prototype, the design issues of the parallel delta-sigma A/D converter are explored and the theoretical pe rformance With no oversampling and with low oversampling is verified, This architecture shows promise for obtaining high speed and resolutio n conversion since it retains much of the insensitivity to nonideal ci rcuit behavior characteristic of the individual delta-sigma modulators .