摘要
针对传统高精度运算放大器输入偏流、失调较大的问题,提出了一种新的偏流补偿结构,通过对输入级拓扑结构和器件方面的改进,使输入偏流比同类运放降低一个数量级以上,同时保持了良好的输入失调,提升了运放的精度;中间级通过设计自举结构,使用少量器件获得了较大的增益,输出级使用了class AB输出结构,避免了交越失真;同时设计了电流增强结构提升了输出级的驱动能力。电路基于标准双极工艺进行设计,仿真结果表明,25°C时输入偏置电流为24.34 pA,失调电流为0.64 pA,失调电压为4.98μV。
Aiming at the problem of large input bias current and offset in traditional high-precision operational amplifier,a new bias current compensation structure is proposed.By improving the topology and device of input stage,the input bias current is reduced by more than one order of magnitude compared with the same kind of operational amplifiers,and good input offset is maintained,which improves the precision of the operational amplifiers;In the middle stage,a bootstrap structure is designed,so a small number of devices are used to obtain larger gain.In the output stage,a class AB output structure is used to avoid crossover distortion.At the same time,a current boost structure is designed to improve the driving ability of the output stage.The circuit is designed based on a standard bipolar process.The simulation results show that the input bias current is 24.34 pA,the offset current is 0.64 pA and the offset voltage is 4.98μV at 25℃,respectively.
作者
任保佳
魏海龙
白欢利
REN Baojia;WEI Hailong;BAI Huanli(Xi’an Microelectronics Technology Institute,Xi’an 710065,China)
出处
《电子设计工程》
2022年第11期163-167,共5页
Electronic Design Engineering
关键词
运算放大器
低偏置电流
低失调
高增益
operational amplifier
low bias current
low offset
high gain
