一个恒定跨导的cmos运放

qerqing

跨导恒定的原理不太懂，文章里说保持Ip+In=IT  可不知道为什么会相等，电路虚线部分不太懂

qerqing

这是图片
C:\Documents and Settings\Administrator\桌面

qerqing

怎么插图片啊？

qerqing

file:///C:/Documents ，这是图片

qerqing

我设的下载不要钱这是一篇IEEE论文，题目是1v rail to rail constant-gm cmos op amp 今年5月份的 getPDF.pdf (205.43 KB , 下载次数: 208 )

2009-10-10 19:49 上传

点击文件名下载附件

qerqing

帮帮忙了

lgy737

下载扣了5元

sspa

ulsi123

School paper, school paper, use it at your own risks!

I downloaded and read the paper, here's a summary of these two authors' ideas:

1. You need to push the two diff pairs M1-M2 and M4-M5 to weak inversion region;
2. Constant-gm is achieved by keeping the total tail currents of the two diff pairs constant (gm is proportional to the drain current);
3. The gm control circuit is a replica bias, and Ip is controlled by the input common mode voltage.

The Vibas for M7 & M8 could be more tricky, but the authors have never mentioned it in the paper.

So IMHO, if the headroom is not an issue, go for traditional ways to design constant-gm opamps.

qerqing

谢谢楼上的答复，m7,m8应该是一直被偏置在饱和状态吧，如果m4,m5截止的话，m1,m2,m7,m8不就是折叠式共源共栅结构吗，m7 ,m8的偏置应该好处理吧