急，关于运放的问题

chaoxianzhu

请各位指点一下，一个两级的运放，前级是差放管，后级是共源做输出，怎样通过加电容电感的方法增加他的增益贷款呢？

Young_W

放大器的增益主要和“小信号负载"有关，增加感性负载可以增加高频时的增益
带宽常常有电路中的零点和极点的位置觉得，通过增加一个右半平面零点可以抵消一左半平面极点，从而增大带宽，推荐看看allen的书

shiunger

Right half plane zero will degrade the phase margin.
You'd better move the zero to left half plane.

jiandanxiaoyu

First, get value of compensation cap, C=gm/wt. Then you can use some methods, such as to make the freq. of zero be equal to the freq.  of second dominant pole, or to push the zero even to the LHP, which means increase the value of resistor and this method can increase your bandwidth 20%.