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Why the lvds wave of true lvds tx channel is worse than the lvds wave of Emulated lvds tx when use true and Emulated lvds tx at the same time?

Lambert
New Contributor I
868 Views

Hi everyone,

I accounted one problem when I use true and emulated lvds tx at the same time. For Arria V GX FPGA, I use the same lvds_tx ip for Emulated and True lvds tx which serial factor is 2, and Emulated lvds tx has one additional altiobuf ip compared to True lvds tx. In addition, the Emulated IO standard is LVDS_E_3R, True lvds IO standard is LVDS. When I view wave of the pin of Emulated tx and the pin of True tx, I find that the wave of Emulated tx will better than True tx , and the wave of True tx more likes noise, hardly see the waveform as a differential signal. It's so strange. Can anyone give some suggestion?

 

Thanks,

Lambert

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1 Solution
Lambert
New Contributor I
673 Views

The problem is that Emulated and True tx should use the same I/O standard ----- LVDS_E_3R.​

View solution in original post

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4 Replies
Lambert
New Contributor I
674 Views

The problem is that Emulated and True tx should use the same I/O standard ----- LVDS_E_3R.​

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Rahul_S_Intel1
Employee
673 Views

Thanks for the acknowledgment and sharing the solution.

 

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Lambert
New Contributor I
673 Views

Hi RSree,

The above solution is wrong, because I don't insert terminating resistor when I monitor the lvds wave on the true lvds I/O, so it's okay to use lvds standard for the true lvds I/O interface.

 

Lambert

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Rahul_S_Intel1
Employee
673 Views

Hi ,

 it's okay to use lvds standard for the true lvds I/O interface. - okay fine

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