运放的偏置电路

wqrqr

偏置电路，偏置电流也会影响的

g9213706

用電流源的角度下去設計才對，用偏壓點的角度想常常沒辦法跑遍所有CORNER

eli20060909

Thanks

Chilton

Current source has high output impedance therefore it's usually not that difficult to generate a "startup/Iref" block for an OpAmp. Base Iref also can be tailored for the bias current requirement of the input/output stages. Usually people starts from architecture design, followed by input/output stages and finish with startup/Ibias cell, with the assumption that you already know how to do a known-good startup/Ibias circuit.

How do you know how good your Ibias cell work? Well, a quick look would be to read the datasheet. A good Ibias cell is PVT robust, so you will find the unloaded supply current for your design is relatively tight with regard to PVT, and this info can be found from the IC's datasheet.

peleGuo

可能自己实践一次，就得到答案了。

草莓咖啡因

很有帮助的帖子，我也初学模拟电路设计，也在迷惑偏置电路该如何设计，除了上述的观点，不知道，偏置电路和主电路一切设计，协调仿真是否可行呢？

azhen1987

因为设计中,我们更看中的是运放支路电流的大小,偏置电压虽然说可以转换成偏置电流,但是受工艺随电源电压的影响,我们不能确定到底需要一个多大的偏置电压,而用偏置电流通过电流镜象给运放,这个电流相对稳定.

peleGuo

我认为，从事物发展客观顺序上，应该是先确定拓扑，再设计偏置。

ebook128

个人觉得运放中作为电流源的管子应该用电流镜偏置，而其它cascode级别的偏置电压可以先用理想电压源替代，然后进行电路调试，最后把理想电压源用其它偏置电路替代。但是肯定会对电路性能有影响，这个还需进一步分析。如果分析得透彻，反而可以指导你如何设计偏置电路。

luweiwei

能结合具体电路来讲就好了。