Monotonic switching method and circuit for successive approximation type analog-digital converter

Abstract

The invention relates to a monotonic switching method and circuit for a successive approximation type analog-digital converter. The monotonic switching method and circuit are used for n-bit analog-digital conversion. The monotonic switching circuit comprises a comparator and (n-1) bits of binary system switching capacitors, an upper electrode plate of the first capacitor in each pair of capacitors is connected with a positive phase input end of the comparator and a difference input signal end VINP, an upper electrode plate of the second capacitor in each pair of capacitors is connected with a negative phase input end of the comparator and a difference input signal end VINN, and a lower electrode plate of each pair of capacitors is selectively connected with reference voltage VREF or a ground end GND. Sampling is carried out through the upper electrode plates, primary power consumption is avoided, the unit capacitor number is reduced, switching power consumption is greatly reduced through the monotonic switching method, and the circuit is simple and reliable in structure.

Description

technical field [0001] The invention relates to the field of digital-analog hybrid integrated circuit design, in particular to a method and circuit for monotonous switching of successive approximation analog-to-digital converters. Background technique [0002] The switching process of the successive approximation analog-to-digital converter with traditional structure is as follows: figure 1 shown. figure 1 where C is the unit capacitance, V INP , V INN is the differential input signal, V REF is the reference voltage, GND is the ground terminal, V DACP is the comparator positive input, V DACN It is the negative input terminal of the comparator, and MSB (Most Significant Bit highest capacitance) here refers to the maximum capacitance. figure 1 In the sampling phase, the upper plates of all capacitors are connected to the input common-mode voltage V CM , the lower plate is connected to the differential input signal. After sampling, disconnect the upper plate of the capa...

AI Technical Summary

Problems solved by technology

It can be seen that the problem of the switching timing of the traditional structure is: more capacitance is required, resulting in greater power consumption

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