一种高增益高驱动能力的运算放大器

运算放大器作为模拟集成电路和数模混合集成电路中的核心模块之一,其性能决定着整个电子系统的品质。本文提出了一种新颖的高增益高驱动能力运算放大器结构,其第一级采用共源共栅结构提高增益,第二级采用提出的跨导增强型推挽输出级,在保留高增益的同时,实现高驱动的性能。此外,基于本文提出的跨导增强型推挽输出级结构,可进一步分裂密勒补偿结构产生的极点,从而在使用较小密勒电容的情况下提升运算放大器稳定性。基于0.35μm BCD工艺对提出的运算放大器进行验证,结果表明在静态电流为84uA时,该放大器在3V^5V的供电电压下,低频增益为95dB,-3dB带宽在100Hz,单位增益带宽在14.4MHz附近,输出抽灌电流可分别达到15.6mA和2.4mA。

Operational amplifiers, whose performance determines the quality of entire electronic systems, are one of the core modules in analog integrated circuits and digital-to-analog mixed integrated circuits. A novel high-gain and high-drive operational amplifier is proposed in this paper. A cascode structure is adopted as the first stage to improve the gain, and the second stage is realized by the proposed transconductance-enhanced push-pull output stage, which can achieve high drive performance while retaining the high gain. In addition, with the help of transconductance boosting in proposed circuit structure, the poles generated by Miller compensation structure can be further divided. This can enhance the stability of operational amplifiers even with a smaller Miller capacitance. The presented operational amplifier has been verified in a 0.35 IX m BCD process. The results show that the low frequency gain of the amplifier is 95dB, and the -3dB bandwidth is 100Hz with 14MHz unit gain bandwidth. The output source and sink current can reach 15.6mA and 2.4mA, respectively with 84 Ix A quiescent current.