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
page, please do.
Below are all of the forum threads, including all
the responses to the original posts.
Post subject: decoupling and coupling.. Posted: Fri Apr 21, 2006 3:50 am
Joined: Sun Apr 09, 2006 8:48 pm
good day everybody,
explanain definition of coupling and decoupling? what is their's purpose? how is their connection in RF matching
Post subject: Posted: Fri Apr 21, 2006 8:33 am
Joined: Mon Jun 27, 2005 2:02 pm
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.
Post subject: Posted: Fri Apr 21, 2006 9:11 am
Joined: Sun Aug 03, 2003 2:02 pm
Location: Erie, PA
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
…just another data point.
- Kirt Blattenberger
Progenitor & Webmaster