Self-calibrated 12 bit SAR ADC structure and self-calibration method thereof

Abstract

The invention discloses a self-calibrated 12 bit SAR ADC structure and a self-calibration method thereof, and belongs to the technical field of analog to digital conversion. The structure includes a self-calibrating capacitor array, a selective switch S [6 : 0], a comparator, a voltage divider resistor string, a register and two logic control modules. A lower pole plate of the self-calibrating capacitor array is connected to the negative end of the comparator or common mode level V<COM>, and an upper pole plate is connected to input voltage V<REF> or V<SS> through a selective switch S [6 : 4];a lowest capacitor upper pole plate is connected to the voltage divider resistor string by selecting a voltage dividing coefficient through a selective switch S [3 : 0]; the output end of the comparator is connected to the register; and the register is connected to the two logic control modules. The self-calibration method of the 12 bit SAR ADC structure is also provided, so that the imbalance ofthe comparator can be precisely eliminated, the imbalance can be presented in the form of calibration codes, the internal imbalance voltage of the comparator can be calculated according to the calibration codes, and whether the magnitude of the imbalance can be accepted and the imbalance is completely eliminated can be judged.

Description

technical field [0001] The invention relates to the technical field of analog-to-digital conversion, in particular to a self-calibrating 12-bit SAR ADC structure and a self-calibrating method. Background technique [0002] In recent years, with the wide application of digital signal processing technology in electronic systems, higher requirements have been put forward for the speed and accuracy of ADC based on CMOS technology, and its performance and implementation directly affect the physical signal processing of the entire circuit system. Range and production cost, so an ADC with low power consumption, high speed, high precision and small area is particularly important. [0003] With the development of semiconductor technology, the more common ADCs on the market are as follows: double integral type, flash type, pipeline type, successive approximation type (SAR), and ∑-△ type, etc., which can respectively achieve accuracy and speed. extreme needs. The successive approxima...

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Problems solved by technology

[0006] The purpose of the present invention is to provide a self-calibrating 12bit SAR ADC structure and a self-calibrating method to solve the problem of low conversion accuracy due to offsets generated in the existing analog-to-digital conversion process

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