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RE: XAUI electrical issues

DC "impedance" is not defined well. You probably want to say that DC
resistance can not be measured. The impedance at the required frequency
range of the traces is needed in order to define the return loss
requirement. For trace impedance of 100 ohm +/- 10 ohm as defined in the
draft, receiver impedance of 80-120 ohm can be used in order to meet the 10
dB return loss requirement. There is no contradiction between the two and
the impedance can be measured even if the capacitors are integrated in the
chip, however I agree that the receiver impedance requirement is not
necessary as long as the trace impedance tolerance is defined.
Israel Greiss,   Chief Technology Officer, MystiCom Ltd.
P.O. Box 8364,      Netanya 42504,          Israel
Tel: 972-9-8636450	            FAX: 972-9-8636466

-----Original Message-----
From: Kesling, Dawson W [mailto:dawson.w.kesling@xxxxxxxxx]
Sent: Friday, September 22, 2000 12:57 AM
To: 'stds-802-3-hssg@xxxxxxxx'
Subject: XAUI electrical issues

2. Both transmitter and receive impedances are defined by the 10 dB return
loss requirement. There does not appear to be a need to define DC
"impedance" as 100 ohms since a) it contradicts the return loss requirement
due to normal parasitic capacitances and b) it is not directly measurable if
AC coupling capacitors and resistive terminations are both integrated into
an IC.
Dawson Kesling
Intel Corporation
916 855-5000 ext. 1273