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Original question:

DS90UB913A-Q1: Unexpected behavior of serdes

DS90UB913A-Q1: The waveform of DOUT and RIN

na na78
Guru 16770 points
Part Number: DS90UB913A-Q1

I attached captured waveform for confirmation of normal serdes operation.(DS90UB913A and DS90UB914A)

E2E_post.xlsx

The Setup sheet shows measuring point.

And Measurement 1 and Measurement 2 shows result with questions.

1.

In the sheet of Measurement 1, there is a common mode voltage and it seems to be varied.

Is it correct behavior?  If not correct, can you point the cause of it?

2.

In the sheet of Measurement 2, the waveform is greatly different from the waveform at measurement 1.

(But the there is no issue for serializing and deserializing operation)

Is it normal waveform?

BestRegards

  • 0
    TI__Mastermind 30515 points
    Hi Na,
    yes, it is correct as FPD-Link III supports bi-direction application in your case including forward channel and back channel. the FC is used for video data transmission plus some bandwidths for control signals such as I2C etc.. the back channel is used for control signal such as I2C, GPIO etc.

    regarding the difference between measurement1 and measurement2, it is due to the cable (~7m) channel loss and reflection which impacts the high speed signal transmission. so inside UB914a, it has internal adaptive EQ to compensate the FC signal loss.

    regards.
    Steven