LVDS Transceiving on a 5m cable

Hello,

You are probably looking for a LVDS buffer/repeater.

Please go to ti.com and search for "LVDS repeater" an example is the DS90LV004

Regards.

Hello, 

First I would like thank you for your answer.

So this device allows me to amplify my LVDS with its internal configurable pre emphasis mode. The outputs match to amplified LVDS,Those can be transferred with a 5m- cable.

How could I determinate the cable lenght  vs LVDSFrequency? To receive the amplified LVDS,must I use another device for a data processing ,like serDes,or i don't need it.

Do you know what is pre emphasis "high","medium"?Because the amplification levels aren't said 

Thank you.

The cable will have a low pass frequency characteristic.  The actual characteristic will be dependent upon the type of cable that you are using, and the length.   If the low pass characteristic is such that the signal degradation at the receive end is liable to create errors, then the cable must be compensated for.   There are two main ways to compensate for the loss characteristic of the cable and different systems use one, the other or both.  The first method is to use a driver to drive the signal into the cable which has a complementary high pass characteristic.  Depending on how it is done, this is called either 'Preemphasis' or 'De-emphasis'  The other method is to put a high pass filter in the receiver, which is commonly known as equalization.  

Thank you for your answer. I have discovered a Texas Instruments device called "Buffer/Repeater", here the datasheet :http://www.ti.com/lit/ds/symlink/ds90lv004.pdf .

There is a pre emphasis mode that allows to boost signal. There is a note that said " The repeater function is especially useful for boosting signals for longer distance

transmission over lossy cables and backplanes". According to you, must I use a very sheldied cable ? beacuse i want to use a category 5 cable, it may be too much!

Thank you for your reading.

The loss will be a function of both frequency and cable length.   CAT 5 cable was designed for characteristics of up to 100MHz, so if you are using it at the maximum data rate of 1.5Gbps of the 'LV004, you are operating well beyond what CAT 5 was intended to run at.  On the other hand, your distance of 5m is not that long.   Belden 1583A Cat 5e cable is specified for a loss of 0.22dB/m at 100MHz, or 0.32dB/m at 200MHz - so at 200 MHz (which will support 400Mbps data rates), you have approx 1.6dB of attenuation at the 5m length - which is quite manageable.   Chances are, with only 5m you would be able to exercise the 'LV04 at it's full 1.5Gbps data rate through 5m of CAT5 cable.

Thank you for your answer.

Ok,  a  Belden 1583A Cat 5e cable allows to have a low attenuation . With a such low attenuation, it is not probably necessary to use a buffer /repeater like the LV004 or a SerDes? or it is better  to use the LV004 with its pre emphasis mode ,to amplify the LVDS in order to have a workable signal? 

Thank you for your reading.

It is not necessarily better - if you over emphasize the signal, then you have too much high frequency content, and this could lead to ringing at the receiver which would result in poor quality transmission as much as underemphasis.

The DS90LV004 pre-emphasis is programmable (via the PEM pins), and so you can select the optimum level of pre-emphasis in your particular application.