讨论一下offset

rocflying

2级放大器的比较器结构，为了减小systen offset，第2级放大管的w/L是不是一定要满足使第一级负载管的VGS=VDS？
貌似这样的话比较器的延迟有点大，增益也不容易提高。

要是第二级放大管的W/L随便取，system offset最大是不是 Vcc/Avo ？

fishbone53

我不会，但是我帮你顶

sxzong_hit

路过，帮顶~~

tianbian360

yes, only this can decrease the system offset.
1, Do your current mirror matching, so VGS=VDS is ok.
2. gm high(input pair work weak inversion region)
3. DC gain hign

tianbian360

4, Input pair size Big Enough

wind2000sp3

This is a trade-off, speed and offset, to improve both, you can enlarge the tail current. But you will fall into another trade-off: speed and power dissipation.
You need to find out your requirement and optimize the parameter you really want, then sacrifice others won't make you upset.

liiru

原来高手都是用英语搞定一切，看来英语真的很重要啊！

goodsilicon

   

This is a trade-off, speed and offset, to improve both, you can enlarge the tail current. But you will fall into another trade-off: speed and power dissipation.
You need to find out your requirement ...
wind2000sp3 发表于 2010-5-17 10:49

                               
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说得有点玄，但好像没理解搂主的意思。。。。

magicdog

计算 system offset，把delta Id折算到输入的delta Vth上去
通常很少去优化第2级的w/l来满足Vgs=Vds，对第一级的delta Id带来的offset采用长沟道器件可靠性要好很多.

baby02204270

系统偏移电压,有公式的