sar ADC circuit

Abstract

The present invention provides a SAR ADC circuit, including a sampling switch circuit, a first DAC capacitor array module, a second DAC capacitor array module, a comparator and a logic control circuit, and the first DAC capacitor array module is introduced through additional expansion in the SAR ADC circuit , and since the capacitance value of the capacitor corresponding to the weight bit of the capacitor in the first DAC capacitor array module is the capacitance value of the capacitor corresponding to the lowest weight bit in the second DAC capacitor array module, the first DAC capacitor array can be passed Module to correct the actual output of the comparator corresponding to the lowest weight bit in the second DAC capacitor array module, and can be derived to the comparator output corresponding to the 0.5LSB weight that the second DAC capacitor array module does not have, so as to solve the problem of high integration, The bottleneck problem encountered in the design of high-speed and high-precision SAR ADC greatly reduces the difficulty of comparator design and directly improves the overall conversion accuracy of SAR ADC.

Description

technical field [0001] The invention relates to the technical field of integrated circuits, in particular to a SAR ADC circuit. Background technique [0002] With the rapid development of technologies such as integrated circuits, the Internet of Things, and sensor networks, as well as people's urgent needs for services such as smart homes and smart medical care, various miniaturized, low-power sensors are used as the link between the physical world and various smart devices. Bridges are getting more and more attention. Sensors can perceive various analog signals in the world, and then convert the analog signals into digital signals through an analog-to-digital converter (Analog to Digital Convert, ADC), and then send them to the back-end digital circuit system for calculation and processing , and then control the equipment to respond, and the ADC is used as the interface between the analog circuit and the digital circuit, and is an important bridge between the analog signal...

AI Technical Summary

Problems solved by technology

For example, in the three modules of SAR ADC, designing a high-speed and high-precision comparator is one of the cores of preparing a high-speed and high-precision SAR ADC, and it has become the main direction of current research, but high precision means that the comparator must be The identified signal is very small, so the comparator needs to have a large gain. High speed means that the comparison time of the comparator must be very short, and the bandwidth of the pre-amplifier that achieves high gain will inevitably decrease, especially in the comparison process of low-weight bits. The signal equivalent to the input terminal of the comparator is very weak, and considering the influence of noise, so in the design, it is necessary to focus on optimizing the gain, bandwidth and noise of the comparator, and the design difficulty will also be greatly increased, corresponding to current consumption and chip area. will also increase, which becomes a bottleneck in the design of highly integrated, high-speed and high-precision SAR ADC

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