一种恒跨导轨对轨CMOS运算放大器的设计  

Design of a Novel Constant Gm Rail-to-Rail CMOS Op-Amp

作　　者：薛超耀[1] 韩志超[1] 欧健[1] 黄冲[1] 

机构地区：[1]西安电子科技大学电路CAD研究所,陕西西安710071

出　　处：《电子科技》2013年第9期121-123,130,共4页Electronic Science and Technology

摘　　要：设计了一种新颖的恒跨导轨对轨CMOS运算放大器结构。输入级采用轨对轨的结构,在输入级采用4个虚拟差分对管来对输入差分对的电流进行限制,使运放的输入级跨导在工作范围内保持恒定。输出级采用前馈式AB类输出结构,以使输出达到全摆幅。仿真结果显示,在5 V电源电压和带有10 pF电容与10 kΩ电阻并联的负载下,该运放在共模输入范围内实现了恒跨导,在整个共模输入范围内跨导变化率仅为3%,输出摆幅也达到了轨对轨全摆幅,运放的开环增益为108.5 dB,增益带宽积为26.7 MHz,相位裕度为76.3°。A novel constant transconductance rail-to-rail CMOS operational amplifier is proposed in this paper. Its rail-to-rail input stage consists of four MOSFETS as dummy differential pairs to limit the current of the differential pair to provide a constant transconductance value within the ranges for the operating region. A front-feed class AB output stage is used to ensure that the output swing achieves rail-to-rail. The simulation results show that the input common-mode range reaches rail-to-rail with a variation of the gm of only 3 % ; the Op Amp performs an open-loop gain of 108.5 dB, the unity gain bandwidth is 26. 7 MHz, and the phase margin 76. 3°when the circuit driving a output load of 10 pF//10 kΩ under 5 V power supply.

关 键 词：轨对轨 恒跨导 AB类输出级 CMOS运算放大器 

分 类 号：TN792[电子电信—电路与系统]