does altlvds have termination 100 ohm setting_

You have to set the terminations explicitly. The ALTLVDS_RX component will not do it for you, since it can not know whether you have already used an external termination.

If you use Tcl, the constraint is of the form:

set_instance_assignment -name STRATIXII_TERMINATION DIFFERENTIAL -to $port

where $port is the signal name.

Cheers,

Dave

Hi Dave,

Thanks very much for the information.

Quartus II v11.1 says

"Stratix devices support internal differential termination with a nominal

resistance value of 137.5 Ω for LVDS input receiver buffers."

Strange, it needs 100 Ω, but the internal resistance is 137.5 Ω, why?

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One more question, in my design, rx is assigned to rx(p), and LVDS standard is selected, the corresponding rx(n) is not connected to anything. Will the fitter assign rx(n) automatically to make a pair of them as a singal channel of rx? If so, is the termination still need?

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The pairs are fixed on the FPGA. Quartus will infer the correct n pin. You can either let Quartus infer it, or you can make a pin assignment to the n pin. You just have to name it correctly, eg., "mysignal" for the p pin, and "mysignal(n)" for the n pin.

Cheers,

Dave

--- Quote Start ---

Quartus II v11.1 says

"Stratix devices support internal differential termination with a nominal

resistance value of 137.5 Ω for LVDS input receiver buffers."

Strange, it needs 100 Ω, but the internal resistance is 137.5 Ω, why?

--- Quote End ---

Table 5-31, page 165 of the Stratix II Handbook:

http://www.altera.com/literature/lit-stx2.jsp

Indicates the terminations are 100-Ohms +/-20 percent.

Cheers,

Dave