一种低压恒跨导轨对轨CMOS运算放大器设计  

Design of a low-voltage constant transconductance rail-to-rail CMOS operational amplifier

作　　者：高瑜宏 李俊龙 Gao Yuhong;Li Junlong(Lvliang University,Lvliang 033000,China)

机构地区：[1]吕梁学院

出　　处：《电子技术应用》2020年第1期48-51,56,共5页Application of Electronic Technique

摘　　要：介绍了轨到轨恒定跨导运算放大器输入级电路设计。所提出的电路通过使用虚拟输入差分对动态地改变输入差分对的尾电流来获得恒定跨导gm。引起总跨导gm变化的因素是输入对和虚拟输入对在共模输入电压变化时不能同时生效,当输入对关闭时输入对的尾电流晶体管处于三极管区域当共模电压变化时,虚拟输入对将在输入对之前从截止区域进入亚阈值区域。在低电源电压设计中,此因素的影响更突出。为了解决这个问题,采用添加补偿电流源到每个虚拟输入差分对的尾电流晶体管,以降低跨导gm的变化。所设计的运算放大器输入级的gm变化误差约为±2%。This paper presents a rail-to-rail constant transconductance operational amplifier input stage. The proposed circuit changes the tail current of the input differential pairs dynamically for a constant-gmby using dummy input differential pairs. The problem which causes total gmvariation is input pairs and dummy input pairs can not take effect at the same time with the com-mon-mode input voltage changes, because the tail current transistor of the input pairs are in triode region when the input pairs are turned off, the dummy input pairs will enter subthreshold region from cut-off region before the input pairs when common-mode voltage changes. The effect of this problem is more obviously in low supply voltage design. To solve this problem, compensate cur-rent sources is added to the tail current transistors of each dummy input differential pairs for lower gmvariation. The gmof this Op Amp ′ s input stage varies around ± 2 %.

关 键 词：轨对轨 运算放大器 补偿电流 

分 类 号：TN431.1[电子电信—微电子学与固体电子学]