一种应用于ADC带曲率补偿的高精度带隙基准源

摘要

设计了一种应用于工作电压为1.8 V的流水型模数转换器（ADC）的带隙基准源。与传统电流模式带隙基准源不同，该带隙基准源采用曲率补偿技术，降低了温度系数，提高了精度。分析提高电源抑制比的方法，设计低压共源共栅电流镜偏置的折叠式共源共栅运放，提高了带隙基准源的电源抑制比。采用CSMC 0.18μm CMOS工艺，获得了900 mV的带隙基准， Spectre仿真结果表明，带隙基准源正常启动，在-40~125℃温度范围内温度系数低至3 ppm/℃，低频时的电源抑制比达89 dB。%A high⁃accuracy bandgap reference source used for curvature compensation of 1.8 V pipeline ADC was designed. Different from traditional current⁃mode bandgap reference source,the curvature compensation technology was adopted in this bandgap reference source,which reduced low temperature coefficient and improved precision. The methods to improve PSRR are analyzed in this paper. A folded cascode amplifier with the bias of high⁃swing cascode current mirrors was designed,which im⁃proved PSRR of bandgap reference source. Based on the CSMC 0.18 μm CMOS process,the bandgap reference gains an output voltage of 900 mV. Simulation results indicate that the circuit can start up normally,the temperature coefficient is 3 ppm/℃ be⁃tween -40 ℃ and 125 ℃ and the PSRR is 89 dB at low frequency.