LTC6560 range walk error

Hi ADI expert,

I have a LIDAR application and my signal chain like as: APD-->LTC6560 --> Comparator --> FPGA.

Since to LTC6560 showed output response time different when small or larger current input, usually called range walk error. Pls refer to as picture figure10.

Any method to reduce the walk error at LTC6560? Thanks.

Best Regards.

Ray Wang.

  • 0
    •  Analog Employees 
    •  Super User 
    on May 25, 2021 9:24 PM

    Hi RayW,

    I got the information below from some folks who have experience in this regard:

    "Walk error is caused by implementing a threshold in the comparator and not the TIA.

     

     

    One effective method to cancel walk error is to detect both the rising and falling edge times and take the average.

      "

    I'm hoping this might help answer your question?

    Regards,

    Hooman

  • 0
    •  Analog Employees 
    •  Super User 
    on May 26, 2021 4:16 PM in reply to Hooman

    Hi again RayW,

    Another expert suggested the following regarding the comparator "walk error" you raised:

    "If you have two comparators set at two different thresholds you can  get the edge slope and get a better estimate of the leading edge."

    I hope these comments help you out.

    Regards,

    Hooman

  • Hi Hooman,

    Thanks for your reply.

    For the LTC6560, this method did not work. It is because the LTC6560 make the rising time all line up and push the fall time based on the signal input. I mean the output waveform from TIA is not symmetrical due to amplitude. If it is not symmetrical, this method does not work. Any other suggestion? 

    Ray Wang.