Capacitor mismatch and offset voltage correction method applied to high-precision successive approximation type ADC

Abstract

The invention discloses a capacitor mismatch and offset voltage correction method applied to a high-precision successive approximation type ADC. According to the method, a correction DAC and a corresponding logic control circuit are added on the basis of a traditional SAR ADC structure, and within a period of time when a chip is powered on, through switch-on / off control of the correction DAC and a main DAC, information of capacitor mismatch and information of comparator imbalance are calculated and stored, deviation information in the memory is read into the correction DAC in a normal working mode, and the deviation is compensated in the form of analog quantity. According to the method, mismatch correction of each capacitor and offset correction of the comparator are included, the correction precision can be changed by changing the capacitor scale of the correction DAC, the correction DAC can meet the design requirement of the high-precision SAR ADC, and the method can be widely applied to circuit design of the high-precision SAR ADC.

Description

technical field [0001] The invention belongs to the technical field of analog-to-digital converters (Analog-to-Digital Converter, ADC), and in particular relates to a capacitance mismatch and offset voltage correction method applied to a high-precision successive approximation ADC. Background technique [0002] The analog-to-digital converter is the core module that converts analog signals into digital signals. It is widely used in the fields of consumer electronics, military industry, aerospace and industry to complete the work of A / D conversion. ADC can be divided into flash type (Flash), pipeline type (Pipeline), integral type (Sigma-Delta), and successive approximation type (SAR) according to different working methods; different ADCs are used in different fields and have different performances. [0003] Flash ADC has a simple structure and fast conversion speed, but it consumes high power, and is suitable for high-speed and low-precision fields; PipelineADC is composed o...

AI Technical Summary

Problems solved by technology

[0012] The deviation of the process will not only cause the capacitance mismatch of the SAR ADC, but also cause the offset voltage of the comparator to be too large, which will affect the comparison result and cause a bit error.

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