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Original question:

OPT3101: Calibration Questions

OPT3101: OPT3101 Calibration Questions ----xtalk offset too large

user4370495
Expert 1155 points
Part Number: OPT3101

Dear TI:

I Design a pcb used opt3101  and found xtalk offset too large compared with EVM board. doc.files 
log.doc

readI2C: 88 , addr: 59, data: 18229

readI2C: 88 , addr: 60, data: ffd25a

readI2C: 88 , addr: 59, data: 181e1

readI2C: 88 , addr: 60, data: ffd25a

iphase_xtalk: 18229, qphase_xtalk: ffd25a, iread: 181e1, qread: ffffd25a, mRead: 98785

c0: 16, small: 65536, big: 131072, xtalkScale: 2

（The laser tube is opened to cover the pd receiver tube, and the xtalk is large. ）

Test process：1.Turn on the power， 2.Block pd，do measureAndCorrectInternalCrosstalk、measureIllumCrosstalk，3. remove pd obstacle，do measurePhaseOffset with a fixed distance。
The register read and write are all  ok.

Can you give me some advise how to address the problem ? thanks  

  • 0
    TI__Mastermind 25855 points
    Hi,

    Can you give the amplitude or crosstalk values measured after correction with the PD still masked? I'd like to understand the residue crosstalk you are seeing.

    Best,

    Alex
  • 0 in reply to Alex Bhandari-Young
    Expert 1155 points

    Dear Alex:

    Residue crosstalk,  maybe come from pcb layout, can you help to check on it. thanks

    The current resistance-capacitance magnetic bead components are all purchased according to the reference version of bom.
    The capacitor used is Murata. The pcb is an immersion gold process, and the laser emission module is purchased by a manufacturer specializing in laser ranging modules.

    schematic:

    X6 TOF sch.pdf

    pcb layout: 4-Layer
    top layer:


    Bottom layer:


    GND Layer:


    VCC Layer:


     

     

  • 0 in reply to user4370495
    TI__Mastermind 25855 points
    Hi,

    I am not seeing any glaring problems from first glance over this layout. We can go a bit more in depth if you like. If you share a picture of the setup any details on metal shielding between the emitter and photodiode I can check this as well.

    Section 2.4 Crosstalk and performance of www.ti.com/.../slau791.pdf has some more details as well on debugging crosstalk.

    Specifically refer to the sub-points under "Common problems encountered in this process: • Crosstalk amplitude reported is very high. This could be due to a number of reasons" on pages 4 and 5.

    Best,

    Alex