10位40MSPS模数转换器片内基准电压源设计

The Design of the On-Chip Voltage Reference in the 10bit 40MSPS Analog-to-Digital Converter

设计了10位40MSPS的ADC片内面积小、高精度的基准电压源,采用带隙电压源为基本结构,重点设计了一种新型的高增益、宽输入范围的CMOS运算放大器,以提高基准电压源精度;并设计出两组基准电压RET与REB,及其差值为ADC的基准比较电压,以进一步减小绝对误差.采用Chart0.35μmCMOS工艺参数进行了Hspice仿真,所设计的运算放大器增益为88dB,基准电压源的随电源电压变化的偏差小于5mV,温度系数小于10-4/°C.经流片测试所设计的基准电压源能很好地满足ADC的要求.

The on-chip voltage reference in 10 bit 40MSPS ADC has been designed. It features high precision, small area, etc. The band-gap reference is used for its basic configuration. Other innovations include a novel type CMOS operational amplifier with high gain, a wide input range with a view to improving the reference precision and two group voltage references RET and REB, the difference between which acts as the comparative voltage reference to reduce the reference absolute error. The Hspice simulation with Chart CMOS 0.35 μm shows that the op-amp gain is 88 dB, that the standard deviation of the voltage reference is lower than 5 mV and that the temperature coefficient is lower than 10^(-4)/(°C). The testing result shows that the designed voltage reference can meet ADC need after taping out.