Successive comparison type AD converter

Abstract

The invention relates to a successive comparison type AD converter. The successive comparison type AD converter comprises: an AD conversion module, a reference voltage conversion module, a comparison module and a successive approximation register. A reference voltage is compared with an input voltage in the comparison module after being converted by the reference voltage conversion module. The successive approximation register adjusts the next reference voltage according to a comparison result output by the comparison module. The invention has the following advantages: a used capacitance quantity can be greatly reduced; a circuit area can be greatly reduced. Therefore, the converter is especially suitable for a system which needs using multipath AD simultaneously. Preferably, the converter is especially suitable for being applied in a touch chip. Because the touch IC needs to collect multipath capacitances, the multipath AD converts of the invention can be used simultaneously.

Description

technical field [0001] The invention relates to an analog-to-digital conversion circuit in the field of digital integrated circuits, in particular to a novel successive comparison AD converter. Background technique [0002] Charge-transfer successive comparators are commonly used circuits in integrated circuits. The structure of the traditional charge-transfer successive comparator is as follows: figure 1 As shown, among them, Vin is first pre-sampled, and the charge of VIN is stored in all capacitors, and the digital quantities of 0 and 1 are generated by successively multiplying and reducing the capacitance and comparing it with Vref. However, in this circuit, since a large number of capacitor arrays are required, and in the production process of integrated circuits, the unit capacitor occupies a relatively large area, and the cost performance is not high. And in order to get better performance and eliminate noise, quite a lot of capacitors are needed to make a symmetric...

AI Technical Summary

Problems solved by technology

However, in this circuit, due to the need for a large number of capacitor arrays, and in the production process of integrated circuits, the unit capacitor occupies a large area, and the cost performance is not high.

And in order to get better performance and eliminate noise, quite a lot of capacitors are needed to make a symmetrical structure, so it is not suitable for small integrated circuits or circuits that require multiple ADs

Images