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ADS54J60EVM: Count spikes on histogram

Maurício Ferreira
Prodigy 150 points
Part Number: ADS54J60EVM
Other Parts Discussed in Thread: ADS54J60, ADS54J40

Hello,

I'm using ADS54J60EVM and TSW14J56 to analyze the electrical noise of 1GHz photodetector. When plotting the histogram I've noticed that the histogram is off as it seems that there's a spike in the number of counts every 4 or so bins. This also occasionally happens when no input is applied.

Is this behavior expected? 

Thank you for your help!

When no signal is applied:

  • 0
    TI__Guru* 91947 points

    User,

    If your analog input is DC coupled you may have to freeze or bypass the offset correction function. Download the latest version of the ADS54J40 data sheet which has been recently updated to included more information regarding this. This is basically the same part as the ADS54J60 but 14 bits instead of 16.

    Regards,

    Jim

  • 0 in reply to jim s
    Prodigy 150 points

    Hi Jim,

    Freezing the offset correction function after powering up the board seems to have fixed the issue. However, I am not using a DC coupled analog input. Do you have an explanation? Maybe I didn't understand how the DC offset correction block works. Sorry if this is all rather obvious, but I'm  quite inexperienced in these matters.

    Regards