ADC (Analog to Digital Converter) circuit adopting single-ended conversion successive approximation structure

Abstract

The invention discloses an ADC (Analog to Digital Converter) circuit adopting a single-ended conversion successive approximation structure. The ADC circuit comprises a capacitive conversion array, a common-mode voltage storage capacitor, a common-mode voltage input end, a comparator, an SAR (Successive Approximation) control logic and a multiplexer switch, wherein upper pole plates of all capacitors are connected together, and lower pole plates are respectively connected to a plurality of input sources through a multi-way analog selector switch; the multiplexer switch is connected to a negative end of an input signal and a negative end of reference voltage, the SAR control logic controls the multiplexer switch, so that the lower pole plate of the common-mode voltage storage capacitor is connected to the negative end of the input signal in a sampling stage, and is connected to the negative end of the reference voltage in a conversion stage at the end of sampling. According to the ADC circuit, a system detuning problem caused by uneven signal and chip reference ground planes is effectively eliminated without increasing the cost of a chip and a system, so that accuracy of measurement is improved.

Description

Technical field [0001] The present invention relates to integrated circuits, especially digital-to-analog converter (ADC) circuits for system measurement. Background technique [0002] When the digital-to-analog converter (ADC) chip is used for measurement, it is generally divided into two signal input modes, single-ended and differential. The single-ended connection is that one end is fixedly connected to the reference ground of the chip (or the negative terminal of the ADC reference voltage), and the other end is connected to the input signal, so the ADC input terminal has only one end; this connection assumes that the negative end of the input signal is also the reference ground. The differential connection method is that the positive and negative ends of the signal are connected to the ADC input end as the input signal, so the ADC input end is both ends. Corresponding to single-ended input and differential input, ADC internal conversion methods are also divided into single-e...

AI Technical Summary

Problems solved by technology

However, the function of the above-mentioned patent application is not much different from that of the differential input. Its capacitor array is connected to the positive and negative terminals of the comparator in a vertical relationship. In fact, it only improves the measurement accuracy of the ADC itself, and it is still powerless to the internal mechanism.

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