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RE: 850 nm solutions


Thanks for informing us the need for a short jumper cables.

Probably, the 850 nm VCSEL solution for a short jumper is also a very

Furthermore, VCSEL is EMI free.  I saw so many EMI issues on the reflector
due to the copper cables, which will consume a lot of resources from
development and add cost to the product.
I think, for 10GbE short jumper, we should focus on VCSEL solution.

A serial 10 Gbps VCSEL transceiver, using installed MM fiber can reach 50
meter with the optimum launch, and easily reach 20 meter even use the
non-realistic OFL bandwidth, 160 MHz-km.

A 4 parallel lines of copper at 6 meter is not necessarily cheaper than a
serial 850 nm VCSEL at 50 meter solution which is EMI free.


Edward S. Chang
NetWorth Technologies, Inc.
Tel: (610)292-2870
Fax: (610)292-2872

-----Original Message-----
From: owner-stds-802-3-hssg@xxxxxxxx
[mailto:owner-stds-802-3-hssg@xxxxxxxx]On Behalf Of THALER,PAT
Sent: Wednesday, April 26, 2000 2:08 PM
To: Rick Walker; stds-802-3-hssg@xxxxxxxx
Subject: RE: 850 nm solutions

Infiniband will be using something very similar to the HARI interface over
short copper links though the distance goal is, I think, 6 m. To travel over
short copper cables, it may make sense to use a 4 wide signal from HARI
rather than 10 Gbit/s serial.

-----Original Message-----
From: Rick Walker [mailto:walker@xxxxxxxxxxxxxxxxx]
Sent: Wednesday, April 19, 2000 4:58 PM
To: stds-802-3-hssg@xxxxxxxx
Subject: Re: 850 nm solutions

> Jim Tatum writes:
> But why does it matter? Why limit the users? Why not put in the table. It
> costs nothing.  Just put in what the model and data tell us to.  It is
> my opinion that a large percentage of 10GB style links are going to be
> very short, less than 10m.  If you look at the way many fiber ports
> are being used today, many are in the 10m range.  Also, since copper
> cables are going to be EXTREMELY challanged to go that distance at
> 10GB, why not let the market choose the lowest cost solution using
> 850nm VCSELs and 62.5um fiber?

FWIW, I agree that 10G across CAT-6 or other twisted pair would be very
difficult.  However 10G across coaxial cable is fairly easy.  It can be
done with 0.1" diameter coaxial cable using simple NRZ data encoding.  A
simple FIR pre-equalizer can double this distance.  Without a doubt
copper would be the cheapest solution for links under 10M.  I would
estimate a mature chipset price of about $50 per end and $15 for the

This performance was demonstrated in 1998 using a 25GHz bipolar chipset.
See: Walker, R. C., K. Hsieh, T. A. Knotts and C. Yen, "A 10Gb/s
Si-Bipolar TX/RX Chipset for Computer Data Transmission" , ISSCC Digest
of Technical Papers 41(February 1998), 302,303,450.

A Copper PHY was voted down by the committee because it was thought that
there was no market for this type of low-cost short distance link.

kind regards,
Rick Walker