RE: [IBIS-Users] Oscillator output

Garry

I assume you are asking - I have a buffer that is continuously clocking, how
do I extract the IV curves so I can make a IBIS model?

I've had to do this in the past on similar components. The VT tables are
relatively easy except you do not have a good trigger point for your scope.
Ideally you would trigger off one event that is synchronous to the clock
output and measure the clock output with your scope when terminating the 50
Ohm load to both ground and Vdd. You cannot trigger off the signal itself
because the trigger point will change when you change the termination
voltage. This will invalidate the timing relationship between the edges.
So, if your oscillator has complimentary outputs trigger on one and measure
the other. If not you will have to find some other way of triggering the
scope that preserves the correct timing.

The IV curves will be more time consuming to acquire. We have done this by
using the 50 Ohm load and incrementally changing the termination voltage.
Every increment in Vt will give you the IV curve by looking at the top and
bottom of the output on the scope. One you have swept the termination
voltage between ground and Vdd for a 50 Ohm load you may want to go back and
reduce the load to say 25 Ohms to get more of the curve, depending on your
component's characteristics.

I hope this helps

Tom Dagostino

Teraspeed Consulting Group LLC

Device Modeling Division

13610 SW Harness Lane

Beaverton, OR 97008

503-430-1065

tom@teraspeed.com

Teraspeed Consulting Group LLC

2926 SE Yamhill St.

Portland, OR 97214

http://www.teraspeed.com

Teraspeed (SM) is the service mark of Teraspeed Consulting Group LLC

  -----Original Message-----
  From: owner-ibis-users@server.eda.org
[mailto:owner-ibis-users@server.eda.org]On Behalf Of
garry.felker@conexant.com
  Sent: Wednesday, April 07, 2004 5:12 PM
  To: ibis-users@server.eda.org
  Subject: [IBIS-Users] Oscillator output

  IBIS experts,
  If you have an output buffer that is a self generating oscillator (33MHz)
how would you approach making an IBIS file for it?
  The user is expected to connect to it with an impedance of 240K ohms.
  Thanks
  Garry Felker

  ==================== 04/07/2004 05:17:44 PM MailFilter-2
====================
  This email may contain confidential and privileged material for the sole
use of the intended recipient. Any unauthorized review, use or distribution
by others is strictly prohibited. If you have received the message in error,
please advise the sender by reply email to help@conexant.com, and delete the
message. Thank you.

|------------------------------------------------------------------
|For help or to subscribe/unsubscribe, email majordomo@eda.org
|with just the appropriate command message(s) in the body:
|
| help
| subscribe ibis <optional e-mail address, if different>
| subscribe ibis-users <optional e-mail address, if different>
| unsubscribe ibis <optional e-mail address, if different>
| unsubscribe ibis-users <optional e-mail address, if different>
|
|or email a written request to ibis-request@eda.org.
|
|IBIS reflector archives exist under:
|
| http://www.eda.org/pub/ibis/email_archive/ Recent
| http://www.eda.org/pub/ibis/users_archive/ Recent
| http://www.eda.org/pub/ibis/email/ E-mail since 1993
Received on Thu Apr 8 09:15:15 2004