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结合精确度和稳定性的要求提出了一种适合宽范围电容负载的CMOS运放.在多径嵌套式密勒补偿结构中加入一个抑制电容,得到适合各种电容负载的稳定性.为了证实稳定性的提高,对该结构进行了理论分析并计算得出数学表达式.基于这种新的频率补偿结构,利用CMOS 0.7μm工艺模型设计了样品芯片.测试结果表明该运放可以驱动从100 pF到100μF负载电容,直流增益为90dB,最小相位裕度为26°.该运放在100 pF负载情况下单位增益带宽为1 MHz,抑制电容仅为18 pF.
In order to meet the requirements of accuracy and stability, a CMOS op amp suitable for a wide range of capacitive loads is proposed, and a suppression capacitor is added to the multipath nested Miller compensation structure to obtain the stability suitable for various capacitive loads. Stability of the structure, the theoretical analysis of the structure and calculate the mathematical expression based on this new frequency compensation structure, the use of CMOS 0.7μm process model design of the sample chip.The test results show that the op amp can drive from 100 pF to 100μF load capacitance with a dc gain of 90dB and a minimum phase margin of 26 ° The amplifier has a unity gain bandwidth of 1 MHz and a suppression capacitor of only 18 pF at 100 pF load.