Subject: Problem with clocked driver

From: "Hassan Ali" <[email-masked]>
Date: Thu, 31 Aug 2000 13:18:27 -0500

I'm trying to create an IBIS model of a differential driver from its
encrypted HSPICE model. The driver operates with the P and N outputs each
terminated with 50 ohm to VDD (=1.8V). This driver has a couple of unusual
characteristics:

- transient simulation shows that at time=0 the driver output is around
950mV regardless of the input stimulus voltage.
- the driver has a clock input as one of the driver subcircuit parameters.
The driver output follows the driver input stimulus only upon receiving a
rising clock edge.

Does anybody know how I should go about creating the IBIS model of this
driver (say using s2ibis2 program)?

Thanks.

Hassan.

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From: "Hassan Ali" <[email-masked]>
Date: Thu, 31 Aug 2000 16:24:33 -0500

Just in case my question wasn't clear, I'm attaching below a PDF file that
illustrates the driver behaviour. The PDF file shows three plots. The top
plot is the driver output for the input stimulus shown in the middle plot
and the clock input shown in the bottom plot.

Please observe that the driver output stays low disregarding the input
stimulus change from low to high. The output only changes to high when the
driver receives a rising clock edge. The challenge here is on how to
generate the V-I curves?

Any ideas?

Thanks.

Hassan.

-----Original Message-----
From: Ali, Hassan [KAN:0G15:EXCH] 
Sent: Thursday, August 31, 2000 2:18 PM
To: ibis
Subject: Problem with clocked driver

Thanks.

Hassan.

---

From: "Muranyi, Arpad" <[email-masked]>
Date: Fri, 1 Sep 2000 08:03:52 -0700

Ali,

This buffer seems to have flip/flop in it which doesn't seem to get
initialized correctly at t=0 and both its pullup and pulldown drivers
seem to be on at t=0.  This could be fixed if you could initialize
some of the internal nodes for t=0 using the .IC statement.  However,
you can ignore this and just clock the buffer a few times before you
begin the actual sweep to get the IV curves.

So, to get a pulldown IV curve, I would set the input low, wiggle the
clock and then sweep the IV curve.  To get a pullup IV curve, I would
set the input high, wiggle the clock and then sweep the IV curve.

Arpad Muranyi
Intel Corporation
=====================================================================

-----Original Message-----
From: Hassan Ali [mailto:[email-masked]]
Sent: Thursday, August 31, 2000 11:18 AM
To: ibis
Subject: Problem with clocked driver

Thanks.

Hassan.