[SI-LIST] Re: USB2.0 simulation by XTK!
- From: "David Fogel" <dfogel@xxxxxxxxxxxxxxx>
- To: JackWCLin@xxxxxxxxxxxx,"Si-List (E-mail)" <si-list@xxxxxxxxxxxxx>
- Date: Wed, 11 Dec 2002 10:56:27 -0800
Jack,
You are mixing here two separate issues. The High Z series element between
the two pins has to do with the automatic parsing of a diff net by XTK. The
translator puts a high impedance (~ 1MEG) resistor between the two pins of
the transmitter. This has no effect on the simulation results. If the model
is properly constructed and the net is properly extracted then the display
should show you a roughly symmetrical waveform around the X axis. This is
the A+B summation of the diff signals at the receiver. It has been working
correctly for quite some times.
David Fogel
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx
[mailto:si-list-bounce@xxxxxxxxxxxxx]On Behalf Of Jack W.C. Lin
Sent: Wednesday, December 11, 2002 2:58 AM
To: Si-List (E-mail)
Subject: [SI-LIST] USB2.0 simulation by XTK!
Dear All SI friends:
I am doing USB2.0 simulation by XTK. But I found I can't get a correct
voltage swing for D+ and D- signal. For high speed mode, the voltage swing
should be around -400mV to +400mV. But the result from simulation is around
0 to +400mV. I check the waveform on reference load at driver end, it's
amplitude is 0 to +400mV. But differential type simulation by XTK seems to
connect two differential pin with series High Z. It will not generate D+
with 0 to +400mV and D- with 0 to -400mV at driver end. I add two 45 ohm
resistor to GND for D+ and D- at far end (USB connector) seperately. How can
I get correct voltage swing for D+ and D-? Modified IBIS model or others?
Thanks
Jack
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