A low-powerlow-voltage slew-rate enhancement circuit for two-stage operational amplifiers  

作　　者：束晨 许俊 叶凡 任俊彦 

机构地区：[1]State Key Laboratory of ASIC&System,Fudan University,Shanghai 201203,China [2]Microelectronics Science and Technology Innovation Platform,Fudan University,Shanghai 200433,China

出　　处：《Journal of Semiconductors》2012年第9期131-136,共6页半导体学报（英文版）

基　　金：supported by the National Science&Technology Major Project(No.2009ZX03007-002-02);the Program of Shanghai Subject Chief Scientist(No.08XD14007);the Shanghai Municipal IC Design Special Program(No.097062);the Special Research Projects for PhD Education(No.20100071110026)

摘　　要：A novel circuit is presented in order to enhance the slew rate of two-stage operational amplifiers. The enhancer utilizes the class-AB input stage to improve current efficiency, while it works on an open loop with regard to the enhanced amplifier so that it has no effect on the stability of the amplifier. During the slewing period, the enhancer detects input differential voltage of the amplifier, and produces external enhancement currents for the amplifier, driving load capacitors to charge/discharge faster. Simulation results show that, fora large input step, the enhancerreduces settling time by nearly 50%. When the circuit is employed in a sample-and-hold circuit, it greatly improves the spur-free dynamic range by 44.6 dB and the total harmonic distortion by 43.9 dB. The proposed circuit is very suitable to operate under a low voltage （1.2 V or below） with a standby current of 200 μA.A novel circuit is presented in order to enhance the slew rate of two-stage operational amplifiers. The enhancer utilizes the class-AB input stage to improve current efficiency, while it works on an open loop with regard to the enhanced amplifier so that it has no effect on the stability of the amplifier. During the slewing period, the enhancer detects input differential voltage of the amplifier, and produces external enhancement currents for the amplifier, driving load capacitors to charge/discharge faster. Simulation results show that, fora large input step, the enhancerreduces settling time by nearly 50%. When the circuit is employed in a sample-and-hold circuit, it greatly improves the spur-free dynamic range by 44.6 dB and the total harmonic distortion by 43.9 dB. The proposed circuit is very suitable to operate under a low voltage （1.2 V or below） with a standby current of 200 μA.

关 键 词：slew-rate enhancement two-stage operational amplifier low-voltage operation low-powerconsump- tion 

分 类 号：TN722.77[电子电信—电路与系统] TN949.12