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How to characterize a LVDS transmitter?

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vbhupendra

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LVDS Transmitter

my lvds transmitter is of cmos switch type. how do i characterize it ?
what is the simulation setup should i use ?
 

suhas_shiv

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LVDS Transmitter

Hi,

Please go thru the LVDS specifications. You can get some information here

https://www.national.com/appinfo/lvds/0,1798,100,00.html

The output swing has to be between 250mV - 450mV with a 100 Ohm resistor. Thats means the current should be atleast 2.5mA. You should bias your transmitter for around 3.5mA. Also keep in mind that the output common mode level should be in the range 1.125V - 1.375V (ideally 1.25V).

Try doing a DC analysis first to set your bias and then do a transient analysis to see the output. Most of the times, the input to the transmitter is either a LVTTL or LVCMOS. It can be different in some cases. It depends on your application.

Ideal LVTTL input would be a square wave( Vil max =0.4V, Vih min 2.4V). You can try simulating with 0 to 3V pulse or maybe 0.2V to 2.6 V pulse. Again set your input tr and tf depending on what your application is.
 

lianghuamo

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LVDS Transmitter

How to modeling the bondwire and the wire on the PCB?
 

dumbfrog

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Re: LVDS Transmitter

Follow the EIA/TIA-644 Spec

VOS, VCM, VD, speed, etc.
 

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