斩波运放讨论

jiang330226

有没有人做过斩波运放啊！大家讨论一下啊！关于PSS＋PNOISE仿真
我做完PSS+PNOISE仿真后，可以在频谱图上看出，奇次斩波频率处有运放输入对管和负载管的1/f噪声，但是这个噪声值相当大，达到了V/sqrt(Hz)了，后面经过低通滤波后也有几十mv/sqrt(Hz),这是不是有什么问题啊！大家有没有相同的 问题？

audiopa

斩波的频率大于信号的带宽＋corner频率，小于运放带宽的1/10。

jiang330226

楼上的兄弟，运放的带宽是指闭环3dB的带宽还是运放的单位增益带宽呢？多谢！

lqlcug

   问一个问题，.noise是要在.ac下使用的，如果用斩波的话，那得用瞬态分析吧，而做瞬态分析的时候好像没有噪声模型啊，楼主是怎么做到斩波时候仿真噪声的，希望指导一下

chengyue2006

xiexieO(∩_∩)O谢谢

nesta

   

原帖由 lqlcug 于 2008-11-18 08:39 发表

                               
登录/注册后可看大图

   问一个问题，.noise是要在.ac下使用的，如果用斩波的话，那得用瞬态分析吧，而做瞬态分析的时候好像没有噪声模型啊，楼主是怎么做到斩波时候仿真噪声的，希望指导一下

spectra可以做到

needforspeed

   

原帖由 nesta 于 2009-3-23 17:57 发表

                               
登录/注册后可看大图

spectra可以做到

can you elaborate your method.
I have tried chopper stabilization tech. on an integrator(for a sigma delta modulator), but I could not see any effect of chopper stabilization.
I think it's impossible to simulate chopper satbilization in nosie analysis or pnoise analysis.

prof3

   

原帖由 needforspeed 于 2009-3-27 04:31 发表

                               
登录/注册后可看大图

can you elaborate your method.
I have tried chopper stabilization tech. on an integrator(for a sigma delta modulator), but I could not see any effect of chopper stabilization.
I think it's impo ...

1. For simulation method, acutally some new tools provide transient noise simulation. For other tools, you can try it see the effect by injecting noise to the transient  simulation

2. For chopper stabilization tech. on an integrator(for a sigma delta modulator), 100% sure you can see the effect.  I guess you fail to see it mainly due to either you did not put the source or simulation method wrong.

You can very easily experience the effect of chopper by inject a DC in your integrator of your SDM loop. Do FFT after simulation and you will find DC component is much lower with Chopper.

needforspeed

   

原帖由 prof3 于 2009-3-27 05:58 发表

                               
登录/注册后可看大图

1. For simulation method, acutally some new tools provide transient noise simulation. For other tools, you can try it see the effect by injecting noise to the transient  simulation

2. For chopp ...

thanks for you comments.
I know that new version of spectre have been added transient analysis.I never ran such analysis. I guess this analysis dose not make sense ifyou have only several runs.
I agree with you that by injecting a dc at input of integrator we can experience chopper stabilization. I meant thatit impossible to see chopper stabilization effect in normal noiseanalysis or pnoise analysis.

pz5921087

看看好不好