Subject: [IBIS-Users] Re: [IBIS] ECL Termination Voltage Question
From: Bob Ross (bob@teraspeed.com)
Date: Tue Jan 13 2004 - 08:56:04 PST
Tom:
My responses are in your text.
Bob
Fisher, Thomas wrote:
> All,
>
> I have a PECL driver that I am modeling that has a non-standard load (pi
> network to ground) which results in a larger Vod. (1.2-V vs. 800mV)
> What happens during simulation is the single-ended waveform depicts a
> slowness of the rising edge which results in a plateau effect on the
> rise/fall of the differential waveform. (It looks great when simulating
> in TISpice) Most (P)ECL termination is going to be 50 ohms to Vtt for
> both non-inverting and inverting outputs whereas Vtt = Vcc – 2-V. Under
> the load I am simulating we are using 200 ohms to ground. (customers’
> request)
>
>
>
> Having said that, looking in the 3.2 spec on page 78 under ramp rates
> model_type for output_ECL it mentions 50 ohm resistor to the termination
> voltage (Vterm = Vcc – 2-V). Is this Vterm embedded into the
> specification?
Yes
Is there a way to specify that the load is 200 ohms to
> ground?
Yes, but you must use the [Rising Waveform] and [Falling Waveform]
method and describe the waveform. This will override the [Ramp]
keyword, which cannot correctly specify the situation you describe.
I believe this might be causing the abnormality. Any
> help/insight would be appreciated. Thanks in advance.
>
>
>
> Regards,
>
> Tom Fisher
>
>
>
-- Bob Ross Teraspeed Consulting Group LLC Teraspeed Consulting Group LLC 2926 SE Yamhill St. Device Modeling Division Portland, OR 97214 13610 SW Harness Lane 503-239-5536 Beaverton, OR 97008 http://www.teraspeed.com 503-430-1065 bob@teraspeed.com 503-246-8048 Direct|------------------------------------------------------------------ |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
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