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I choose a device，It's lvds output swing is from 250mV~450mV.
But the sink device is a 1.8V LVDS port which require swing from 100mV~300mV,
How can I connect these two devices？
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I assume you are referring to the Vdiff differential amplitude, correct? Those values would be reasonable for LVDS differential P/N voltage swing.
You don't mention it, but most likely the common mode voltage of the driver Vocm is about 1.25V or so, typical for LVDS, both driver and receiver.
So since the minimum output driver amplitude is 250mV > input receiver minimum amplitude 100mV you should be ok.
I question the maximum receiver input amplitude of 300mV with a minimum required amplitude of 100mV; that value does not seem reasonable to me.
So the summary is, assuming the common mode transmitter/receiver voltages are compatible (as I note), a direct DC connection should be ok.
