Transmitter Device Source Termination

Bill Ham bill_ham at ix.netcom.com
Thu Feb 23 03:51:10 PST 2006


* From the T10 Reflector (t10 at t10.org), posted by:
* Bill Ham <bill_ham at ix.netcom.com>
*
Hi,
The transmitter device includes the connector associated with that device. 
That
transmitter device connector needs to be one of those identified as allowed
for
the specific interoperability point in the standard.  I do not recall that
the SMA
is one of those allowed transmitter device connectors.
Note that the transmitter device is not the transmitter chip but rather the
chip,
board traces, any components that are in the path between the transmitter
chip and
the connector and the transmitter device connector itself (which must be
mated to
the connector on the test fixture to gain access to the transmitter device). 
Assuming
the transmitter device connector is not an SMA or similar that is suitable
for direct
connection to instrumentation, you need to also go through a low loss
instrumentation
connector (like an SMA) mounted on a connector adapter test fixture to get to
the
instrumentation.  See the measurements annex B in 1.1.	So in general one
would
make the measurement through two mated connectors, one on transmitter device
and
one on the test fixture to get to the instrumentation cable.  The
instrumentation
connector should be almost invisible.
However, one could use special instrumentation quality cables that has the
device
connector integral to the instrumentation cable. Multiple cables would be
required
to meet the zero length and TCTF load requirements. Since annex B is
informative
and not normative that possibility is legal.  Or perhaps better stated as not
illegal.
This special instrumentation cable, being part of the instrumentation up to
the
transmitter device connector half that is part of the cable, may have issues
with
calibration since the calibration would have to be to the internal part of
the cable
that is directly connected to the mating transmitter device connector
connection
point.	Maybe some smart person could figure out how to do it.	In any case
the
transmitter device measurements for any interoperability point, including the
IT
point, are made through at least the mated connector pair that is part of the
transmitter
device.
There does not seem to be any ambiguity the way the 1.1 standard is presently
written
except that caused by Annex B not being normative.  I lost that battle.
Cheers, Bill
-----Original Message-----
>From: Ramez.Rizk at emulex.com
>Sent: Feb 22, 2006 1:06 PM
>To: t10 at t10.org
>Subject: Transmitter Device Source Termination
>
>Hi all,
>
>
>
>I was looking at the SAS 2 draft Table 44 page 153 and SAS 1.1 Table 43
>page 149.  In both drafts note b for the measurements requirements says
>the following:
>
>
>
>"All transmitter device termination measurements are made through mated
>connector pairs"
>
>
>
>This does not make any reference to the IT compliance point, which makes
>me believe that it can be done with any connector type as long as they
>are mated, for example SMA mated pair.  Is that assumption correct? If
>not, I think we need to clarify it more in the standard.
>
>
>
>Thanks
>
>Ramez
>
Bill Ham
Phone 7x24 978 828 9102
Fax 978 470-0321
*
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