# what's Meant by Coupling - RF Cafe Forums

The original RF Cafe Forums were shut down in late 2012 due to maintenance issues. Original posts:

guest
Post subject: what's meant by coupling Posted: Mon Sep 12, 2005 4:58 am
i m an undergraduate and starting out in circuit analysis and design and hope to go on to do something in rf field 'cause i like it a lot. i've a very basic question to ask...when people talk about ac coupling capacitor, what they do really mean? exactly, what does coupling exactly mean? i know blocking cap blocks dc signal, bypass cap open circuits the dc signal but i'm not exactly sure what's meant by dc coupling or ac coupling.

any explanation w/ or w/o example will help a lot! thanx

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IR
Post subject: Posted: Mon Sep 12, 2005 6:03 am

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Coupling means how much the signal will pass forward from one point to another. AC coupling is done by means of series capacitor. As the frequency increases the reactance of the capacitor drops, according to the ratio of Xc=1/2*pi*f*C.

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- IR

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guest
Post subject: Posted: Mon Sep 12, 2005 6:37 pm
hi IR, this means that a series capacitor that is used for ac coupling is then also a dc block??

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IR
Post subject: Posted: Mon Sep 12, 2005 11:30 pm

Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Exactly!!

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Best regards,

- IR

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YZ-israel
Post subject: Posted: Wed Sep 14, 2005 1:33 am
you can say DC coupling is the same as High Pass Filter.
It will blocked the DC and the lower Freq. and pass the higher freq.

the 3 dB point for this filter depend on the capacitor and the impedance.[/img]

Posted  11/12/2012

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