Improved 10-bit differential capacitance segmented coupling type DAC

Abstract

The invention discloses an improved 10-bit differential capacitance segmented coupling type DAC. The improved 10-bit differential capacitance segmented coupling type DAC comprises a positive secondary capacitance array, a positive coupling capacitor, a positive main capacitance array, a negative coupling capacitor, a negative main capacitance array and a sampling switch. The improved 10-bit differential capacitance segmented coupling type DAC uses a 12-bit differential DAC to realize the 10-bit differential DAC, the gain error of a 1-LSB is avoided, and the static property of the DAC is improved; and meanwhile, the positive secondary capacitance array, the positive main capacitance array, the negative secondary capacitance array and the negative main capacitance array realize the smaller capacitance through replacing the lowest capacitance in the DAC by unit capacitors in series, and the problem of oversize area due to improving the DAC precision is avoided. The improved 10-bit differential capacitance segmented coupling type DAC has good static property and takes up small area.

Description

technical field [0001] The invention relates to the field of integrated circuit chips, in particular to an improved 10-bit differential capacitive segmental coupling type DAC. Background technique [0002] Successive approximation analog-to-digital converters have the characteristics of moderate speed, moderate accuracy and low power consumption, and are widely used in signal acquisition systems. Differential successive approximation analog-to-digital converters can suppress interference such as power supply noise compared with single-ended ones, and are generally used in 10-bit to 12-bit successive approximation analog-to-digital converters. The basic structure of the differential successive approximation analog-to-digital converter is as follows figure 1 As shown in the figure, the circuit is mainly composed of differential DAC, switch network, comparator and successive approximation control logic. The use of capacitive differential DAC can realize signal sampling withou...

AI Technical Summary

Problems solved by technology

However, due to the coupling capacitance and the unit capacitance C U There is a relationship of non-integer multiples, so this will bring great problems to the layout design of the DAC. It is difficult to match the capacitors, which will affect the actual capacitance of each capacitor of the DAC and cause the performance of the DAC to decline.

[0005] image 3 For the prior art 10-bit differential capacitive segment coupled DAC structure, it is relative to figure 2 In the early 10-bit differential capacitive segmented coupling DAC, the fringe capacitance was removed, and the coupling capacitance C 6 、C 17 The capacitance value is determined as C U , which can well solve the problem of DAC capacitance matching, but introduces a certain gain error

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