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Altera_Forum
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16 years ago

SerialLite II

Hi, I am trying the seriallite IP on the Stratix II GX signal integrity board and implement a loop back funtion with one TX and one RX. I found that when I disconnected only one of the diff...
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Altera_Forum
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16 years ago

Kent,

yes this is reasonable. A differential input essentially detects the crossing of the plus and minus inputs. If you disconnect an input, internal circuity may or will bias the this pin. This is often/always the case in AC-coupled connections. If the connected signal crosses this bias level the circuit will detect these crossings without distinction. It will probably suffer at higher bit rates, unless the connected signal is totally symmetric around the bias-level of the unconnected pin. Again if you have AC-coupling this will usually be the case.

Regards,

Josy