StratixIV GX and SFP

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I want to communication with 2.5GHz SFP (small form-factor pluggable) models using GXB_RX and GXB_TX pins. In SFP, the tx and rx are AC coupled LVPECL signals.

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At 2.5Gbps per lane, you do not need to use a Stratix IV GT device, you can use a GX device (your title mentions GX, but your post says GT).

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My questions are,

1. how to link GXB_RX and GXB_TX pins with SFP? Just connect them directly or using some voltage level change chips? In the schematic of StratixV developboard, they connect directly.

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Now you say Stratix V! Which device are you really using?

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2. What PCML standard should chose, 1.4 V PCML, 1.5 V PCML or 2.5 V PCML?

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Whatever the transciever power supply is on your development kit.

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3. In configing ALTGX ip, the Vcm is 0.82V or 1.1V?

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You can configure it for either. However, I don't think either will be compatible with LVPECL, so you would want to AC-couple your SFP signals.

Cheers,

Dave