Successive-approximation temporary storage type analog-digital converter and control method thereof

Abstract

The present invention provides a successive approximation register analog-to-digital converter (SAR ADC), where a high bit capacitor of the SAR ADC is composed of a plurality of sub-capacitors, and these sub-capacitors are calibrated when the SAR ADC is working. Therefore, the working speed of the SAR ADC will not be influenced. In addition, a capacitance of each sub-capacitor is lower than a redundant capacitance of the SAR ADC, therefore, input signals of the SAR ADC are allowed to have full swing.

Description

technical field [0001] The present invention relates to a continuous approximation register analog-to-digital converter (Successive Approximation Register Analog-to-Digital Converter, SAR ADC), in particular to a continuous approximation register analog-to-digital converter capable of background calibration device and its control method. Background technique [0002] In the continuous approximation temporary analog-to-digital converter, the capacitance value of each bit capacitor in the bit capacitor array may deviate from the originally designed capacitor due to process errors, ambient temperature changes, or incomplete symmetry / matching. value, resulting in errors in the digital output, which in turn affects the linearity of the continuous approximation temporary register analog-to-digital converter. In order to solve this problem, it is usually necessary to calibrate the bit capacitance. However, some current calibration methods have some problems, such as affecting the ...

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Problems solved by technology

[0002] In the continuous approximation temporary analog-to-digital converter, the capacitance value of each bit capacitor in the bit capacitor array may deviate from the originally designed capacitor due to process errors, ambient temperature changes, or incomplete symmetry / matching. value, resulting in an error in the digital output, which in turn affects the linearity of the continuous approximation register analog-to-digital converter

In order to solve this problem, it is usually necessary to calibrate the bit capacitance. However, some current calibration methods have some problems, such as affecting the working speed of the continuous approximation temporary analog-to-digital converter, or needing to limit the swing of the input signal to Avoid exceeding the coding range of the analog-to-digital converter, etc., thus causing confusion for the designer and flaws in the operation

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