一种低温度系数带隙基准源设计

摘要

The effect,caused by the input offset of the operational amplifier,can be reduced by the utilization of two bipolar in series in bandgap references.But in CMOS process,the forward beta is so small that the current of base has a significant effect on the collector current,which leads to a large drift for the reference voltage.To solve this problem,a base current compensating technique is proposed in a low temperature coefficient bandgap reference.The circuit adopts TSMC 0.25μm process,the simulation results show that the temperature coefficient is 8.44ppm/℃,the reference drift 1.85mV within -55℃ to 125℃.The current of the power only increases 0.5 μA after adopting base current compensation circuit.%采用两个三级管基极－发射极串联的带隙基准可以降低运放失调电压的影响，但是在CMOS 工艺中，三级管的正向电流放大倍数β很小，导致三极管基极电流的分流会对发射极电流产生很大影响，带隙基准输出存在较大温漂。为了解决这个问题，提出了一种带基极电流补偿的低温度系数带隙基准源电路。电路设计采用 TSMC 0．25μm 工艺，经过 spectre 仿真验证，进行－55℃－125℃的温区扫描，基准随温度变化范围为1．85mV，相应的温漂系数为8．44ppm ／℃，加入基极电流补偿电路后电源电流只增加了0．5μA。