这个运放第二级怎么工作的？

typhoon222

这个运放红色框内这部分是怎么工作的呢？

AcoAco

typhoon222 发表于 2019-10-9 10:00
图更新了下

Within the dashed line, there is a second phase, "Class AB", with no feedback other than the Miller capacitor. The leftmost four transistors invert the first stage output to drive the n-ch output transistors. These four transistors operate in Class A mode. The left 2 of the leftmost 4 transistors are constant current pull-up p-ch (labeled Pm) and pull-down n-channel (labeled Nn) whose current depends on the state output p-channel state (if the output p-ch off => Nn off). When Nn is turned off, Pn will output an n-ch gate pullup. The diode-connected device limits the gate voltage of the output n-ch. There is another weak current sink device in parallel with the diode-connected device, most likely one of the op amp shutdown devices (or ENABLE or DISABLE). The overall op amp operates at class AB. The total complete circuit is an operational amplifier with a "negative feedback" from its output to the input. Two capacitors are Miller capacitors for op amp compensation (stability).

fcm5658779

中间那两个管子的源级接啥

AcoAco

它是一个反相单级运算放大器，用于驱动n通道输出。 原理图很小，所以我看不到细节，但看起来它已配置为单位增益缓冲器。

typhoon222

fcm5658779 发表于 2019-10-8 16:36
中间那两个管子的源级接啥

接电源，图更新了下

typhoon222

AcoAco 发表于 2019-10-8 22:05
它是一个反相单级运算放大器，用于驱动n通道输出。 原理图很小，所以我看不到细节，但看起来它已配置为单位 ...

图更新了下

fcm5658779

红色部分与第二级构成一个负反馈，可以稳定输出电压的共模电平。

老尤皮

是class AB，红色部分是为了得到输出级nmos的驱动电压

typhoon222

老尤皮 发表于 2019-10-9 10:43
是class AB，红色部分是为了得到输出级nmos的驱动电压

右下方那个二极管连接的管子是做什么的？输出端电容是米勒补偿？

Thomas_Bai

1) 你确定这是运放？第二级输出是反馈回输入的?
2) 网上有没有paper参考？