[SI-LIST] Re: Impedance measurement

  • From: "Jeff Loyer SI" <jeff.loyer.si@xxxxxxxxxxx>
  • To: <dharanidhar.signalintegrity@xxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
  • Date: Wed, 12 Aug 2015 15:09:51 -0700

A TDR is basically a pulse generator and an oscilloscope. If you have
these, you can build your own. You can "crudely" determine the
characteristic impedance of your PCB trace by terminating one end of it with
a variable resistor while you inject a pulse from the other end and observe
that injected waveform with your oscilloscope. When the resistor's value
matches that of the trace's impedance, there will be no reflection at the
termination. This is only going to be a crude approximation, but it used to
be good enough for many applications. For most of today's high speed
signaling, it's not accurate enough, but it's better than nothing.

Good luck,
Jeff Loyer
Signal Integrity Engineering


-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx]
On Behalf Of dharanidhar chatrathy
Sent: Wednesday, August 12, 2015 8:53 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Impedance measurement

I am looking to measure impedance of a trace on a PCB. What is the
simplest way to do. I neither have TDR nor the network analyzer. I am
looking for a crude method of measuring it. Please, suggest ways of doing
it.


------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field

or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list

For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field


List forum is accessible at:
http://tech.groups.yahoo.com/group/si-list

List archives are viewable at:
//www.freelists.org/archives/si-list

Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu


Other related posts:

  1. Home
  2. si-list
  3. Archive
  4. 08-2015