Designers can deliver up to 10 Gbits/s
of Ethernet over 30 m of copper cable
thanks to a pair of developments from
Phyworks Ltd. The 24 AWG twin-ax
cable is terminated in SFP+ connector
assemblies that employ the company’s
PHY2060 active equalizer, CDR,
and retimer IC (see
the figure).
The PHY2060 was originally developed
for optical-fiber applications, but it
adapts well to the copper medium. The
complete assembly achieves error-free
transmission with a latency of just 120
ns at 30 m.
This technology is ideal for interconnecting
servers and other equipment in
datacenters. With at least 80% of datacenter
cables less than 30 m long, a copper
interconnect approach offers great
cost savings. Optical-fiber cables based
on the Ethernet 10GBaseSR standard
are the best for such high-speed connections,
but they’re very expensive, ranging
from $400 to $600. Designers can also
use the 10GBaseCX4 copper cable standard,
which transmits over four parallel
3.125-Gbit/s channels.
These cable assemblies are large, bulky,
and heavy, though, and they consume
considerable power. They also still cost
more than $7 per meter. Furthermore,
CX4 cable assemblies need line-card
mounted quad retimers and quad preemphasis
drivers as well as the printed-circuit board (PCB) space to support
eight data lanes. The new Phyworksbased
cable assemblies are 40% smaller,
30% lighter, and far less bulky than CX4
cable. A 30-m cable is expected to cost
around $150.
While Phyworks doesn’t make the
cable assemblies, the PHY2060 is being
used in modules and cable assemblies
currently in trials by cable and connector
OEMs. It’s primarily a receiver chip,
so two devices are used at each end of
the cable. Phyworks expects a singlechip
transceiver using the same effective
equalization and retime capability in the
near future.
