audio/videoZONE Products for the week of May 26, 2003
Intersil Corporation Says . . .
EL9110: Differential Receiver/Equalizer For Video
Over Cat-5 Cable Applications
New Elantec EL9110 offers high bandwidth, low power consumption
Intersil Corporation, a world leader in the design and manufacture of high performance analog and wireless networking solutions, unveiled the first device in a new family of differential receivers/equalizers for video over CAT-5 cable applications. Intersil's Elantec EL9110 features 150 Megahertz (MHz) of bandwidth at -3dB and consumes only 33mA from a 5-volt supply. The EL9110 is ideal for use in twisted-pair receiving, VGA over twisted-pair and security video applications.
"The EL9110 is the first device in a new family of differential receivers/equalizers designed specifically for equalizing video," said Sameer Vuyyuru, director of marketing for Video and Op Amps for Intersil's Elantec Product Group. "Drawing from many years of high performance analog and op amp expertise, we were able to design a product that delivers the performance, low power consumption and reliability that video switch manufacturers demand."
The Elantec EL9110 is used in video switches that typically traverse
1000 foot of cable. The EL9110 contains a high-speed differential receiver
with five programmable poles. The outputs of these pole blocks are summed
into an output buffer. Equalization length is set with the voltage on a
single pin.
analogZONE Says...
Watching this product do its stuff rather reminded me of the first high-frequency PLL I ever built; you push the button and it just works. With the EL9110 you just adjust the control voltage until the signal reflections disappear, and adjust the gain level until the signal at the end of a length of CAT-5 cable is back to rights. The demonstration I received was for both 100 m and 300 m of standard cable.
The secret is that virtually all CAT-5 cables are just about identical in their characteristics. Above 1 MHz skin effects in the twisted pairs increases high-frequency attenuation, but because of cable similarities a single equalizing law can be applied to all.
The architecture of the EL9110 starts with a common-mode extension system for direct-coupled systems (needs to be disabled when ac coupling is used) that reduces the voltage at both inputs of the differential input amplifier as the common-mode signal rises toward the supply; the opposite applies when the common-mode input signal falls, maintaining the amplifier within its common-mode input range. After the amplifier the signal passes to a summing stage which is also fed with a little low-frequency boost and the high-frequency equalizing boost. The control voltage (relative to a common reference for both the equalizer and the following gain stages) varies between about 0.2 V to 1.0 V for 100 m to 300 m of correction. The gain stages (Intersil terms it as "contrast") offers a ±6 dB range to allow for double-terminated loads. The final operation is to convert the differential signal to a single-ended output.
Performance is out beyond 100 MHz with shorter cable lengths and the gain bandwidth is severely rolled off at higher frequencies to reduce noise bandwidth. Positive and negative PSRR are better than 60 dB out to 100 kHz, while THD is better than 55 dB out to 20 MHz. The slew rate is quoted at 1.5 V/ns driving a double-terminated 75 ohm load and the offset voltage is a typical -10 mV with a range from -300 mV to +300 mV.
This is ±5 V supply part with a typical no-load quiescent of about 30 mA and a shutdown lower than 0.8 mA. The outputs can swing within 1.5 V of the rails.
This is a unique part that will enable completely innovative systems; when combined with Power-over-Ethernet capabilities - and one has to believe that Intersil will be offering such solutions - there is the probability of complete security system control and video delivery being over a single CAT-5 cable. That would reduce the installation of such systems down to the level of a person with the ability to mount a camera and absolutely no technical experience. Because of the similarity of manufacturing techniques I would think that the system would work well with other standards of twisted pair cables. With some intelligence available in an application it should also be possible to automate the adjustments by looking at a single transition in the signal.
The EL9110 is in production in QSOP-16 and is priced at $6.75 in 1000-piece lots.