Differential input voltage charge scaling SARADC

Abstract

The invention discloses a differential input voltage charge scaling SARADC, belongs to the field of integrated circuits, and aims to solve the problem that a common multi-bit SARADC circuit needs a large number of capacitors to occupy the area of a chip. The circuit comprises a VREF voltage divider, a capacitor array DAC1, a capacitor array DAC2, a comparator, an SAR logic circuit and an N-bit register. The capacitor array DAC1 and the capacitor array DAC2 both adopt A + B bit combined DAC (Digital-to-Analog Converter), the high bit A part adopts capacitive scaling, the low bit B part adopts reference voltage scaling, and N is equal to A + B; the VREF voltage divider provides voltage for the capacitor array DAC1 and the capacitor array DAC2; differential input signals VREF-AD and AD are accessed to the capacitor array DAC1 and the capacitor array DAC2, the VREF is a system reference voltage, and the AD is an analog input signal; the capacitor array DAC1 and the capacitor array DAC2 respectively output voltage values for N times under the control of the SAR logic circuit, voltage VO1 and voltage VO2 output each time are subjected to difference comparison by the comparator, a comparison result each time is stored in the N-bit register as an effective bit, and a conversion result formed by N times of comparison is output.

Description

technical field [0001] The invention relates to a DAC circuit structure in a successive approximation register type (SAR) analog-to-digital converter (ADC), and belongs to the field of integrated circuits. Background technique [0002] One of the most important functions of signal processing is converting between analog and digital signals. The function of the analog-to-digital converter (ADC) is to convert the input analog signal into the corresponding binary digital character code. Since the analog signal is continuous in time and amplitude, while the digital code is discrete, the ADC system includes a signal sampling and holding process. The successive approximation type in the ADC type is essentially a binary search method. Taking the random number in 1-16 as an example, first determine whether the number is larger or smaller than 8. If the number is larger than 8, then whether it is larger than 12. larger or smaller than 12. The third search narrows down the range of...

AI Technical Summary

Problems solved by technology

[0017] The purpose of the present invention is to solve the problem that the commonly used multi-bit SAR_ADC circuit requires a large amount of capacitors to occupy the chip area and the layout cannot be highly matched, the single-ended analog signal input has weak anti-interference ability, and cannot meet the design requirements of multi-bit high-speed and high-bandwidth ADCs, and provides A differential input voltage charge scaling SAR_ADC

Images