A Low-power High-Linearity Switching Method of Successive Approximation ADC Capacitor Array

Abstract

The invention discloses a low-power and high-linearity switching method for successive approximation register (SAR) ADC capacitor array, which belongs to the technical field of the super low-power design of successive approximation ADC. The method belongs to a switching method of three baselines (Vref, Vcm=Vref / 2 and Gnd=0) based on top-plate sampling; therefore, the scale of the corresponding capacitor array can be reduced by 75% from that of the traditional structure. According to the method, switch control time sequence is initialized; a logic switching mode is utilized featuring the reasonable combination of the down switching and the up switching of capacitors. Under the condition that parasitic capacitance is not considered, the power consumption incurred from capacitor array conversion is only 1.2% of that of the traditional structure; when the parasitic capacitance at the top plate is 10% per unit of capacitor and the parasitic capacitance at the bottom plate is 15% per unit of capacitor, the power consumption incurred from capacitor array conversion is only 1.3% of that of the traditional structure. In addition, compared with the available switching schemes, the method could realize the significant improvement in the linearity of a D / A conversion structure inside an SAR ADC.

Description

technical field [0001] The invention belongs to the technical field of integrated circuits, and relates to successive approximation ADC capacitor arrays, in particular to a low-power-consumption and high-linearity switching method for successive approximation ADC capacitor arrays. Background technique [0002] With the advantages of low power consumption, the charge redistribution successive approximation (SAR) ADC with capacitor array as the main structure has been widely used in implanted bioelectronics systems such as EEG and ECOG, especially those based on upper plate sampling. Triple reference (V ref , V cm =V ref / 2 and Gnd=0) capacitor array switching method, the number of unit capacitors in the corresponding capacitor array is only 1 / 4 of the traditional structure, which is very suitable for application in implantable biomedical electronic systems. In the charge redistribution SAR ADC, the switching mode of the capacitor array not only affects the power consumptio...

AI Technical Summary

Problems solved by technology

The traditional charge redistribution SAR ADC capacitor array switching method corresponds to a large capacitor array, which is not conducive to the optimization of area, matching performance, power consumption and speed

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