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分析了MOSFET失配对差分放大器失调电压影响的机理,介绍了降低失调电压提高精度的斩波调制技术的工作机理,在此基础上实现了一种低电压高精度带隙基准电压源设计.利用斩波调制技术有效地减小了带隙基准源中运放的失调所引起的误差,提高了基准源的精度.考虑负载电流镜和差分输出对各±2%的失配时,该基准源的输出电压波动峰峰值为0.31mV.与未应用斩波调制的带隙基准源相比,相对精度提高了约86倍.当温度在0℃到80℃变化时,该基准源的温度系数小于12×10-6/℃.采用0.25μm2P5MCMOS工艺实现的版图面积为0.3mm×0.4mm.
The mechanism of the effect of MOSFET mismatch on the offset voltage of the differential amplifier is analyzed. The working principle of the chopping modulation technique to reduce the offset voltage is introduced. Based on this, a low-voltage and high-precision bandgap reference design is realized. The wave modulation technique effectively reduces the error caused by the offset of the op amp in the bandgap reference and improves the accuracy of the reference. Considering the mismatch of ± 2% for the load current mirror and the differential output, The peak-to-peak output voltage ripple is 0.31mV, which increases the relative accuracy by about 86-fold over the bandgap reference without chopping modulation.The temperature coefficient of the reference source is less than 12 at temperatures ranging from 0 ° C to 80 ° C × 10-6 / ° C. The layout area of 0.25μm2P5MCMOS process is 0.3mm × 0.4mm.