Multi-bit delta-sigma modulator

Abstract

Disclosed is a multi-bit delta-sigma modulator, which comprises an analog filter, an analog adder, a multi-bit quantizer, a digital loop filter, a multi-bit feedback digital-analog converter and a shunt feedback module. The shunt feedback module comprises at least a high-order multi-bit shunt feedback branch, and each shunt feedback branch comprises a shunt feedback digital-analog converter, a signal shunt unit and an analog adder in the analog filter. By introducing the high-order multi-bit shunt feedback branch, the modulator can reduce the element mismatching noise of the multi-bit shunt feedback digital-analog converter, weaken analog-digital mismatching noise, and reduce the power consumption of the analog filter. The disclosed modulator may be applied to a high-performance analog-digital converter.

Description

technical field [0001] This invention relates to analog-to-digital converters and, in particular, to delta-sigma modulators. Background technique [0002] Delta-Sigma (Δ-Σ, DS) modulator is an important part of DS analog-to-digital converter (ADC). The DS modulator is accompanied by oversampling when it works. Due to the limitation of semiconductor process technology and circuit power consumption, the sampling frequency cannot be increased without limit. Sampling Rate. In order to compensate for the signal-to-noise ratio (SNR) drop caused by this, it is necessary to increase the order of the loop filter or improve the resolution of the quantizer. Under the condition that the resolution of the quantizer is 1 bit, it is difficult to ensure the stable operation of the system with a loop filter exceeding the second order, and improving the resolution of the quantizer can not only reduce the quantization noise, but also enhance the stability of the high-order loop system , is ...

AI Technical Summary

Problems solved by technology

In DEM technology, there is no mismatch (or called analog-to-digital mismatch) problem between the analog filter and the digital filter, the leakage noise is small, and the gain requirement of the amplifier in the integrator is low, but the low order (0 1st-order or 1st-order) DEM technology has weak performance in shaping the mismatch noise of multi-bit DAC components; high-order (greater than or equal to 2nd-order) DEM technology has complex circuit structure and instability problems

In the double quantization structure, cascaded double quantization structure, digital noise shaping loop (DNSL) double quantization structure and digital noise shaping (DNS) double quantization structure all have good loop stability and noise shaping performance, however, there are analog The mismatch problem between the filter and the digital filter, the leakage noise or the analog-to-digital mismatch noise is large, and the gain of the amplifier in the integrator is high.

Therefore, the main problem of DEM technology is that the high-order structure is complex and unstable, and the noise shaping performance is difficult to improve; the main problem of the double quantization structure is the modulus mismatch

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