SAR-type ADC capacitor redistributed array normalized bridge capacitor circuit

Abstract

An SAR-type ADC capacitor redistributed array normalized bridge capacitor circuit relates to an integrated circuit. The low N-bit capacitor array in the invention is composed only of N low-level capacitors, each of which is corresponding to a data bit; the capacitance of the bridge capacitor is 1 unit of capacitance; the bridge capacitor and the data bit capacitor are both composed of X independent unit capacitors, wherein X is a natural number, the value is determined by the location of the capacitor, and the capacitance of each unit capacitor is 1 unit of capacitance. The invention ensures that the entire capacitor array is a unit capacitor, thereby maximizing the conversion linearity of the DA core.

Description

technical field [0001] The invention relates to integrated circuits, in particular to A / D converter circuits with high precision and low power consumption. Background technique [0002] SAR ADC is the classic design scheme of the current mainstream high-precision A / D converter, and its core units are high-precision DAC core, comparator, digital logic and other units. Its static power consumption is mainly concentrated in the DAC core and comparator unit. In order to reduce static power consumption, its DAC core is mostly completed by a capacitor redistribution array, and its conversion accuracy is mainly determined by the internal DAC core unit. [0003] It can be seen from the above that the capacitor redistributed SAR ADC is currently the mainstream low-power, high-precision A / D converter design scheme, and the internal capacitor redistributed array is the core unit that affects the overall ADC conversion linearity. For N-bit SAR ADC, the classic capacitance redistributio...

AI Technical Summary

Problems solved by technology

[0006] Usually, when a process manufacturer manufactures a capacitor array, if all capacitors are unit capacitors, the size of each capacitor and the surrounding environment are completely consistent, the matching of the obtained capacitor array is high (the natural matching degree can be higher than 0.1%); but if the capacitance If there are non-unit capacitors with inconsistent sizes in the array, the matching of the capacitor array in the finished product is poor due to the inconsistent size of the individual capacitors and the surrounding environment (the natural matching accuracy can be lower than 20%)

[0007] In summary, figure 2 Although the segmented capacitor array shown can effectively reduce the number of capacitors used, since the imported bridge capacitor is inconsistent with the size of other unit capacitors in the array, usually after the finished product is manufactured in the craft factory, the mismatch of the bridge capacitor is large. As a result, the conversion linearity of the entire DA core is deteriorated, and ultimately the overall conversion performance of the ADC is deteriorated

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