Delta sigma modulator circuit for an analog-to-digital converter

Abstract

In a delta-sigma modulator for an A/D converter for modulating an analog input signal to produce a modulated signal of a digital form, a first integrator produces a first integral signal indicative of an integral of the difference between the analog input signal and feedback signal, a first delay element delays the first integral signal by one sampling period, a second integrator produces a second integral signal indicative of an integral of the difference between the output of the first delay element and the feedback signal, a first quantizer produces a two-level signal '1' or '0' depending on whether or not the second integral signal is greater than a predetermined reference, and a second quantizer produces a two-level signal '1' or '0' depending on whether or not the first integral signal is greater than a predetermined reference. An output digital signal is produced in accordance with the outputs of the first and the second quantizers. The feedback signal is also produced in accordance with the outputs of the first and the second quantizers.