Sigma-delta modulator

Abstract

The invention is applicable for the field of the signal processing technology and provides a sigma-delta modulator. The sigma-delta modulator comprises a first-class modulation unit, a second-class modulation unit and a noise shaping unit, wherein the first-class modulation unit is used for transforming input analog signals into first-class digital signals; the first-class digital signals comprise quantization noise and multi-bit DAC (Digital-to-Analog Converter) nonlinear noise; the second-class modulation unit is connected with the first-class modulation unit so as to transform the quantization noise and the multi-bit DAC nonlinear noise in the first-class digital signals into second-class digital signals, and feedback the second-class digital signals to the first-class modulation unit; the noise shaping unit is connected with the first-class modulation unit and the second-class modulation unit so as to cancel the quantization noise and the multi-bit DAC nonlinear noise in the second-class digital signals and the first-class digital signals, obtain digital signals without noises and output the digital signals. The sigma-delta modulator counteracts the last-class multi-bit DAC nonlinear errors and upper-class quantization noises in a cascade structure through combining inter-stage feedback with a double quantitative structure.

Description

technical field [0001] The invention belongs to the technical field of signal processing, in particular to a sigma-delta modulator. Background technique [0002] Analog-to-digital converters (ADCs) play a very important role in signal processing. A large number of data converters are required in the fields of digital audio, digital television, image coding and frequency synthesis. As the size and bias of VLSI continue to decrease, the accuracy and dynamic range of analog devices also decrease, which is a challenge to realize high-resolution ADC. The high-order multi-bit sigma-delta ADC is widely used in practice because it does not need a sample-and-hold circuit, the circuit scale is small, and it can achieve high resolution. [0003] Since the birth of Sigma-delta modulation technology in the 1960s, after several years of development, it has become one of the mainstream technologies for realizing high-performance analog-to-digital conversion interface circuits in VLSI sys...

AI Technical Summary

Problems solved by technology

[0014] 1. Use a multi-bit digital-to-analog converter (DAC) in each level of feedback loop. Due to technological reasons, multi-bit DAC will generate nonlinear noise. When the nonlinear noise is large, it will seriously affect the performance of the entire sigma-Delta modulator

[0015] 2. Relevant measures are not used to deal with the nonlinear noise of multi-bit DAC, so that the nonlinear noise of multi-bit DAC is directly output

Images