Custom Search
Over 10000 Pages Indexed
Your Host
Click here to read about RF CafeKirt
Blattenberger

... single-
handedly
redefining
what an
engineering website
should be.

View the YouTube RF Cafe Intro Video Carpe Diem!
(Seize the Day!)

5CCG (5th MOB):
My USAF radar shop

Hobby & Fun

Airplanes and Rockets:
My personal hobby website

Equine Kingdom:
My daughter Sally's horse
riding business website -
lots of info

•−•  ••−•    −•−•  •−  ••−•  •
RF Cafe Morse Code >Hear It<

Job Board

About RF Cafe©

RF Cafe E-Mail

decoupling and coupling.. - RF Cafe Forums

Because of the high maintenance needed to monitor and filter spammers from the RF Cafe Forums, I decided that it would be best to just archive the pages to make all the good information posted in the past available for review. It is unfortunate that the scumbags of the world ruin an otherwise useful venue for people wanting to exchanged useful ideas and views. It seems that the more formal social media like Facebook pretty much dominate this kind of venue anymore anyway, so if you would like to post something on RF Cafe's Facebook page, please do.

Below are all of the forum threads, including all the responses to the original posts.


ngks79
Post subject: decoupling and coupling.. Posted: Fri Apr 21, 2006 3:50 am

Lieutenant

Joined: Sun Apr 09, 2006 8:48 pm
Posts: 2
Location: Penang
good day everybody,

Can anybody explanain definition of coupling and decoupling? what is their's purpose? how is their connection in RF matching circuit?

Thanks


Top

IR
Post subject: Posted: Fri Apr 21, 2006 8:33 am

Site Admin


Joined: Mon Jun 27, 2005 2:02 pm
Posts: 373
Location: Germany
Hello ngks79,

AC or RF coupling is done with a series capacitor which its purpose is to deliver only the alternating or high frequency signal and block the DC in order not to vary the operating point of the active device (Usually transistor or amplifier). These series capacitors are often connected between a matching network and the input or output of the device. Their capacitance should be calculated in a way that their reactance is low in the lowest frequency of operation (not more than few ohms).

Decoupling means suppressing high frequency signals, this is usually done in supply voltages by connecting capacitors between the supply and GND rails. The capacitors short high-frequency signals (Interferers and noise) to GND.

_________________
Best regards,

- IR


Top

Kirt Blattenberger
Post subject: Posted: Fri Apr 21, 2006 9:11 am

Site Admin


Joined: Sun Aug 03, 2003 2:02 pm
Posts: 308
Location: Erie, PA
Greetings:

A similar question was asked of me the other day at work on a related topic, and that was: What is the difference between a decoupling capacitor and a bypass capacitor? The questioner had been told by his college professor that a decoupling capacitor was used in series with an RF signal to block DC, and that a bypass capacitor was used on DC supply lines to shunt AC to ground.

IR's response is in line with my own usage of the term "coupling capacitor" for one used to pass RF and block DC. The terms "decoupling capacitor" and "bypass capacitor" are used interchangeably almost universally in technical literature and on all of the online electronics dictionaries (and app notes) I checked. Both terms describe a capacitor used to conduct AC to ground, or at least away from the signal path.

…just another data point.

_________________
- Kirt Blattenberger
RF Cafe Progenitor & Webmaster


Posted  11/12/2012
A Disruptive Web Presence

Custom Search
Over 10,000 pages indexed! (none duped or pirated)

Read About RF Cafe
Webmaster: Kirt Blattenberger
    KB3UON

RF Cafe Software

RF Cascade Workbook
RF Cascade Workbook is a very extensive system cascaded component Excel workbook that includes the standard Gain, NF, IP2, IP3, Psat calculations, input & output VSWR, noise BW, min/max tolerance, DC power cauculations, graphing of all RF parameters, and has a graphical block diagram tool. An extensive User's Guide is also included. - Only $35.
RF system analysis including
frequency conversion & filters

RF & EE Symbols Word
RF Stencils for Visio

Product & Service Directory
Personally Selected Manufacturers
RF Cafe T-Shirts & Mugs

RF Cafe Software

Calculator Workbook
RF Workbench
Smith Chart™ for Visio
Smith Chart™ for Excel