12位单斜ADC的设计

Design of 12-Bit Single-Slope ADC

介绍的单斜ADC(Analog-to-Digital Converter,ADC)应用于三维成像激光焦平面读出电路,将读出电路检测到的电压模拟信号转换为数字信号,便于后续的信号处理。根据焦平面阵列规格、对信号精度和速度的需求,选择采用单斜结构ADC,其中斜坡发生器和计数器两个模块可以所有列共用,每列只需一个比较器和寄存器。斜坡发生器采用分段电容阵列结构,大大减小了芯片面积。由于ADC精度较高,也对比较器进行了失调校准,同时提出了一种新结构,使得比较器输入范围扩大至轨到轨。提出的ADC基于0.18μm CMOS工艺进行设计,输入电压量化范围为1.1 V,量化精度为12位,转换速度为5 kHz。

The single-slope ADCproposed in this paper is applied to the three-dimensional imaging laser focal plane readout circuit,which converts the voltage analog signal detected by the readout circuit into a digital signal for subsequent signal processing.According to the focal plane array specifications,the signal accuracy and speed requirements,we choose single-slope ADC.Because the ramp generator and counter can be shared by all columns,only one comparator and registers is needed per column.The ramp generator uses a split-capacitor array structure,which greatly reduces the chip area.We also calibrate the comparator offset due to high accuracy requirement of the ADC and propose a newstructure that increases input range of comparator to rail-to-rail.The ADCproposed in this paper is based on 0.18umCMOSprocess,the quantization precision is 12 bits with input voltage quantization range 1.1 V,and the conversion speed is 5 kHz.