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针对传统A类两级运算放大器摆率受限的情况,提出了一种新型的AB类两级CMOS运算放大器。仅通过增加一个电阻和电容,就实现了传统A类运算放大器向AB类运算放大器的转变,以及对输出级静态电流的精确控制,极大地改善了摆率,并且不会增加额外的功耗。新的频率补偿方法在保证系统稳定的同时大大增加了单位增益带宽,同时避免了传统补偿所带来的缺点。仿真结果表明,与传统的A类运算放大器相比,提出的AB类运算放大器的正负摆率分别提高到原来的35倍和2.2倍,单位增益带宽提高到原来的5倍。
A class AB two-stage CMOS operational amplifier is proposed in view of the limited slew rate of the traditional class A two-stage operational amplifier. By simply adding a resistor and capacitor, the transition from traditional Class A op amps to class AB op amps and precise control of the quiescent current of the output stage is achieved, dramatically improving slew rates without adding extra power. The new frequency compensation method greatly increases the unity gain bandwidth while ensuring system stability, while avoiding the disadvantages of traditional compensation. The simulation results show that the positive and negative slew rate of the proposed class AB op amps are increased by 35 times and 2.2 times respectively and the unity gain bandwidth is increased by 5 times compared with the traditional class A op amp.