Dual Feedback Loop Noise Shaping Oversampling Successive Approximation Analog-to-Digital Converter and Method

Abstract

Disclosed is a double feedback loop noise shaping oversampling successive approximation analog-to-digital converter and a control method. In the successive approximation analog-to-digital converter, the capacitive digital-to-analog converter generates a margin voltage on its upper plate through switching, the first margin The acquisition capacitor and the second residual acquisition capacitor are alternately connected to the upper plate of the capacitive digital-to-analog converter in odd and even cycles to store the residual voltage of the current cycle generated by the capacitive digital-to-analog converter, and the passive loop filter passes through The voltage buffer is connected to the lower plate of the capacitive digital-to-analog converter, and the upper plate of the capacitive digital-to-analog converter is connected to the comparator through the integrating capacitor to form a double-loop feedback structure. The comparator combines the input voltage signal with the passive loop filter The sum signal of the output voltage signal is quantized into a digital code, based on the digital code to control the switching of the capacitive digital-to-analog converter, and successively approximate each bit output of the analog-to-digital converter from high to low in a successive approximation manner until the entire quantization Finish.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a noise shaping oversampling successive approximation analog-to-digital converter with double feedback loops and a control method. Background technique [0002] Most signals in the real world are analog signals, and an analog-to-digital converter (ADC) is used to convert analog signals in nature into digital signals. With the rapid progress of integrated circuit process nodes, the successive approximation (SAR) ADC has gradually become a research hotspot in the field of ADC research in recent years due to its advantages of simple structure and excellent adaptability to the process. However, with the increasing demand for ADC effective bits, traditional SAR ADCs are limited by comparator noise and internal analog-to-digital converter (DAC) noise, and the accuracy is often difficult to exceed 12 bits. Therefore, high-precision, low-cost noise-shaping SAR ADC is a new h...

AI Technical Summary

Problems solved by technology

[0003] Some current noise-shaping SAR ADCs use op amp-based active integrators, so power consumption is high and op amp performance varies widely with process, voltage, and temperature (PVT)

Although the power consumption of the pure passive noise shaping structure is greatly reduced, because of the use of passive integrators and multi-input comparators, the number of noise sources is increased and additional signal attenuation is caused, so the noise shaping effect is often limited

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