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You are faced with this seemingly simple question:
What is the connection and difference between bypass (capacitor) and decoupling (capacitor)?
To put it bluntly, most readers are unable to clearly say the exact answer, and even many so-called senior engineers are not immune.
So, as if it had been agreed for a long time, I opened my browser and searched for relevant information on the Internet, trying to find the answer to the question, but unfortunately, the so-called experience on the Internet may not be correct, and I do not know these so-called Who wrote the experience in the first place, anyway, it is reprinted a lot on the Internet, and there is nothing new at all. It is safe to say here: the information on this question is varied, and even a lot of it seems to be contradictory, however, even if you go through it all, there will be no clear answer, and even more people are more confused.
Let's take a look at what the mainstream views on this issue are on the Internet. Let's hold a review conference first, and then give our final answer (one family's words, for reference only):
Comments: If nothing else, there are pictures similar to the following to supplement the above text:
It is really well-illustrated, detailed, penetrating and penetrating. This statement may be easily accepted by most engineers. However, it is still reluctant to explain the difference between decoupling capacitors and bypass capacitors from the different positions of capacitors. Ridiculous! In other words, do not agree with this statement, completely disagree!
Comment: This information should be relatively pertinent, and it is quite close to the idea of our article "The Working Principle of Bypass Capacitors", but the difference between the two is still not clearly pointed out. Is there a difference between bypass capacitors and decoupling capacitors? Of course there is! The difference is big!
Comments: I don't know what I'm talking about, just copy a little from the east and a little from the west! Who said that decoupling capacitors are generally large, isn't 100nF decoupling capacitors very common? And who said bypass capacitors are for high frequencies?
Comments: I don't know whether the original author wrote this passage in this way, or reprinted it like this, four words, it's a mess! It has also been reposted by thousands of people, and even given the word "incisive". It is conceivable that the information on the Internet is seriously distorted, and the reposter has never seriously read the experience that he considers "incisive".
Do you have a capacitor with a distributed inductance of 5uH? If the inductance has 5uH, is it still called distributed inductance? 5nH is the correct solution! Since the resonance frequency of the 0.1uF decoupling capacitor is 7MHz, why the resonance frequency of the 1uF and 10uF capacitors is above 20MHz, which is higher than the resonance frequency of the 0.1uF capacitor. 1nF, 10nF is the correct solution!
However, here's what I'm trying to say: If you read this paragraph with all "decoupling capacitors" replaced by "bypass capacitors", which do you think is correct? Because in the article "The Working Principle of Bypass Capacitors", we also probably indicated that bypass capacitors mean this. Is it wrong in my article, or is the information on the Internet wrong?
Are you getting dizzy? The screenwriters, don't give a shit, reveal the answer, hurry up!
In fact, the difference and connection between the two are very simple, in one sentence: decoupling is bypass, bypass is not necessarily decoupling!
We often mention decoupling, coupling, filtering, etc., which are called from the perspective of the specific functions played by capacitors in the circuit. These names belong to the same concept.