这种运放单位增益响应曲线是否正常？能用不？

AcoAco

回复 16# feynmancgz

Please  understand that at  least intentionally I  do not advise bad design practices. I did not say ringing is typical for a manufactured product since in first place I avoid a designs with less than 16 degree of phase margin and I try to do anything possible to eliminate bumps close to gain plot unity gain crossings. In fact I try so hard to make gain plot as straight as possible around unity gain crossing. Therefore I myself had never seen those ringings in my manufactured designs at all (I am not even familiar with ringing. To my luck I have never seen even an  un-optimal transient behavior) .  What we are talking here is a persons attempt to design an op-amp and during the initial phase of his/her design seeing ringings in the simulations ( At least it is what I understood since there is no mention nor photos of a ringing taken on a scope).

                               
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What is typical is bode diagram with almost zero gain margin during initial design phase as shown on the bode gain plot (as I described it typically occurs with very low power designs due to high parasitic capacitance's and high node impedance's  and I tried to give a few hints to fix that. After fix is done there would be at least 15 degree phase margin and no ringing.

Ideally bode gain plot should be a straight line with no nearby bump up (at least minimally a decade away but farther away the better as long as design constraints/budget allows it)  after passing the unity gain frequency (i.e. all high order poles and zeros ideally positioned at least a decade away of unity gain crossing, better if farther away)  but this requires some design effort with today's very low power designs because high R and C at the nodes and requires some compromises.


I hope this clarify the misunderstanding.


请您理解，至少我不建议故意糟糕的设计手法。
我并没有说振铃是典型的生产的产品摆在首位，因为我用不到一个16度的相位裕度，避免设计中，我尝试做任何可能获得口岸消除颠簸接近单位增益曲线。事实上，我着急使增益曲线尽可能地直，左右交叉的单位增益。阻尼振荡，因此我从来没有见过那些在我的设计制造（我什至不熟悉的铃声。我的运气，我从来没有见过，甚至一个非最佳的瞬态行为）。我们这里所说的是一个人试图设计一个运算放大器和他/她设计的阻尼振荡在初始阶段在模拟中看到的（至少我的理解是正常的，因为那里是没有提及的振铃拍摄的照片一个范围内）。



什么是典型的兆头图几乎为零增益余量在最初的设计阶段，如在波特增益情节（如我所描述它通常OCCURS非常低的功率设计由于高寄生电容的和高的节点阻抗的和我试图得到一些所示提示来解决这个问题。修复程序后，将至少有15度的相位裕度和无振铃。

理想的情况下获得波德图上应该没有附近的凹凸了（至少10年之遥的直线，但距离越远的更好的微创只要作为设计的限制/预算允许它）的统一增益频率合格后（即所有高为了极点和零点理想的位置的单位增益交叉至少十年的路程，更好，更远），但是这需要一些努力，今天的低功耗设计，节点设计，因为它的高R和C，需要一些妥协。

我希望澄清误解。

huanggc1989

回复 21# AcoAco


    AcoAco，are you a foreigner? If not, no intention to offend，why is your translation from English to Chinese so weird?

AcoAco

回复 22# huanggc1989

I realize many posts are pure Chinese and majority of forum people do not know English. I do not know Chinese, but I want to help, so I use Google to translate for those people who do not know English (Particularly to reply the ones who ask in Chinese). I also use Google to translate Chinese and translation is indeed funny   but through some brain work I understand what translated context is meant.This method works so far with this forum though, since pop up windows contents are not translated by Google, I could not figure out how to attach files and do similar activities so I only write if I could give a useful good answer to others  requests.

fortissimo.g

回复 23# AcoAco


    Could u pls recommend some analog design forums ?

AcoAco

回复 24# fortissimo.g

I guess it is not allowed to post other forum names (normally all the forums prohibit such activity). I do not want to get into trouble with forum management. I am sorry.

needforspeed

回复 10# AcoAco


    高人，人家都没说结构

selfsalvation04

all of you are  great analogic IC designers . i hope you can share some typical  circuit  structures or other proplems we always  have to  deal. especially  green IC designers, just like me .  thank you !

huanggc1989

回复 23# AcoAco


    that is really a pleasure to communicate with a foreign designer here, and thanks for your help……by the way,I don't know much about the relationship between the "gain margin" and the stability of the opamp, could you recommend some references about that? thank you~

lgy747

我对外国人接触得不多（都是培训或研讨会场合，我从未出过国），他们，欧洲人，美国人，日本人，韩国人，给我的印象是有修养，懂礼貌，不摆架子，敬业，专业知识强，尤其日本人，特别谦恭。然而在几个外国技术论坛上，我看到的情况是，就专业技术而言，平均水平很一般，不比我们强很多，所以整体来说外国人和我们一样，有牛人，也有垃圾，呈正态分布。当我看到某公司某些人无论什么事，芝麻绿豆的事就打越洋电话请教他亲爹，一打就1个多小时，最后心满意足地，屁颠屁颠地回到他的座位时，我就作呕。在这里，我同样看到了某些人！