LCR parallel resonance

msddw

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Why is the Q of an actual LCR parallel resonant circuit W0L/R? While the Q of an ideal LCR parallel resonant circuit is R/W0L?

userwjp

Why is the Q of an actual LCR parallel resonant circuit W0L/R? While the Q of an ideal LCR parallel resonant circuit is R/W0L?

-The Q values I know are always W0L/R. I want to know where the R/W0L at the end is from.

maychang

“The Q of an ideal LCR parallel resonant circuit is R/W0L?”

Not sure where you saw that Q is R/W0L.

Which book? Post it.

msddw

msddw

Is there any detailed information on this?

maychang

“Is there any detailed information on this?”

The resonance of the RLC circuit is discussed in almost any book on "Circuits" or "Circuit Analysis".

For example

电路 邱关源 第5版.pdf (19.62 MB, downloads: 72)

2019-6-19 15:55 上传

点击文件名下载附件

msddw

msddw

msddw

Q=1/W0CG, isn’t that R/W0C?

maychang

msddw posted on 2019-6-19 16:29 Q=1/W0CG, isn't it just R/W0C?

"Q=1/W0CG, isn't that R/W0C ?"

In your first post you said that "the Q of an ideal LCR parallel resonant circuit is R/W0L ".

msddw

My question is: Why is Q W0L/R when L and R are connected in series and then in parallel with C? And why is it R/W0L when L, R, and C are connected in parallel?

msddw

I can't figure this place out.

maychang

"Q = 1/W0CG, isn't that R/W0C?"

I don't know where Q = 1/W0CG is. There is no such expression on this page.

Pay attention to the expression in the red box. In particular, note that G and R are reciprocals of each other.

msddw

maychang posted on 2019-6-19 17:09 "Q=1/W0CG, isn't it just R/W0C?" I don't know where Q＝1/W0CG is. There is no such expression on this page...

1/W0LG=1/W0L(1/R)=R/W0L

maychang

These two R's are not the same thing.

In the first figure (series resonance), R is connected in series in the resonant circuit. In the second figure, G (that is, R, just take the reciprocal) is connected in parallel with the resonant circuit.

In the previous figure, the smaller R is, the smaller the loss is and the larger Q is.

In the latter figure, the larger R is (the smaller G is), the smaller the loss is and the larger Q is.

So, one must be in the numerator and the other in the denominator.

threetigher

I was confused,,,,