Successive Approximation Analog-to-Digital Converter Calibration Circuit

An analog-to-digital converter and successive approximation technology, which is applied in the directions of analog/digital conversion calibration/test, analog/digital conversion, code conversion, etc., can solve problems such as limiting the accuracy of SARADC, and achieve the effect of improving accuracy

CN105959006BActive Publication Date: 2019-06-11SHANGHAI HUAHONG GRACE SEMICON MFG CORP
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2019-06-11

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Abstract

The invention discloses a successive approximation type analog-to-digital converter calibration circuit which comprises a calibration digital-to-analog converter, a compensation capacitor, a comparator and a digital logic circuit. The calibration circuit is used to calibrate the offset of the comparator in the analog-to-digital conversion and the mismatch of the corresponding bit capacitance of the main digital-to-analogue converter. In the analog-to-digital conversion, the corresponding control code of the calibration digital-to-analog converter is the calibration code of the offset of the comparator, the mismatch calibration code of the conversion bit capacitance and the weight reference voltage of the conversion bit capacitor. The invention can eliminate the influence of the offset of the comparator and the mismatch of the capacitance, especially the high 6-bit capacitance, in the conversion process, so as to improve the precision of analog-to-digital conversion.
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Description

technical field

[0001] The invention relates to the field of semiconductor integrated circuits, in particular to a successive approximation analog-to-digital converter (Successive Approximation Register ADC, SAR ADC) calibration circuit. Background technique

[0002] Successive approximation analog-to-digital converters are widely used in medical equipment, high-speed data acquisition systems, digital signal processing, spectrum analysis, industrial equipment, communications, and engines.

[0003] The error and parasitic effect of the device in the manufacturing process limit the improvement of the accuracy of the SAR ADC. In order to further improve the accuracy, it needs to be calibrated. Contents of the invention

[0004] The technical problem to be solved by the present invention is to provide a successive approximation analog-to-digital converter calibration circuit, which can improve conversion precision.

[0005] In order to solve the above technical problems, the...

Examples

Embodiment Construction

[0044] like figure 1 As shown, in the embodiment of the present invention, the successive approximation analog-to-digital converter includes a main digital-to-analog converter 1 , a calibration digital-to-analog converter 2 , a compensation capacitor Cc, a comparator 3 , and a digital logic circuit 4 .

[0045] The main DAC 1 is a charge scaling DAC composed of a binary weighted capacitor array 101 .

[0046] The calibration digital-to-analog converter 2 is a voltage scaling digital-to-analog converter composed of resistor strings.

[0047] The output terminal of the main digital-analog converter 1 is connected to the first input terminal of the comparator 3, and the input terminal of the main digital-analog converter 1 is connected to the input voltage Vin, the reference voltage Vref and the ground Vgnd through the switch array 102 one of them. figure 1In the shown embodiment of the present invention, the main digital-to-analog converter 1 is composed of a binary weighted c...