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Regarding square wave (~7.8125 kHz) is present at RCLK_OUT (J3) - ADA2200

Hi, 

I have started to use an ADA2200 for the purpose of employing it as a Lock-in Amplifier. 

For starting the operation, I am following the document - ADA2200SDP-EVALZ (Rev. 0) (analog.com).

On page 3, point no. 8, it is mentioned that "Verify that a square wave (~7.8125 kHz) is present at RCLK_OUT (J3). Connect RCLK_OUT to VINP (J7) with an SMA cable".

I am doing that, but getting a frequency of around 63 kHz. I am not sure why this is happening. I would be grateful if you could kindly help me sort this out. 

Thank you in advance 



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[edited by: Shaumik at 11:57 AM (GMT -5) on 1 Mar 2022]
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  • Hi Shaumik,

    I've contacted the assigned engineer for this generic, in the mean time can you share your setup configuration and scope shots for this? It will also help if you can send an actual picture of your board.

    Thanks,

    Kristine

  • Hi Kristine. Please find the document attached for your reference, Let me know if you have any doubts. DOCX

  • Hi Kristine. Can someone help me out with this? A slight help to get it working will go a long way whereby I can spend my time finding out the operation in detail. I am not able to solve why the frequencies are not matching with what is given in the manual after initial basic connections?

  • Hi Shaumik,

    Apologies for the late response, I'm currently looking into this and trying to obtain a board to also bench it on my side. I'm just curious, ADA2200 is not recommended for new design as this generic would be discontinued, would you want another generic for your application? or is there a specific reason why you're currently testing ADA2200?

    Regards,

    Kristine

  • Thanks, Kristine for your reply. Actually, I had purchased it a few months earlier and was not aware that ADA2200 will be discontinued. I was trying to work with the ADA2200, because this is the first time I am building a lock-in amplifier. Earlier, I have used lab based lock-in amplifiers. So, I thought since I have already bought it, if I can learn with this, I can implement my knowledge for future boards as well. 

    Since it will be discontinued, we can go for any other option that can be used as a lock-in amplifier with both amplitude and phase measuring capability for our future designs. Can you suggest an alternative?

    We will go for manufacturing with that and thus we will need something which we can use over the next few years. 

    Regards

  • Hi Shaumik,

    I see. You can check AD630 or LTC6943. In AD630 DS page 18, there is a reference circuit for lock-in amplifier section:

    Also, LTC6943 DS page 10:

    Let me know if you have any specs in mind for your requirement so we can help you in selecting a better amplifier.

    Hope this helps!

    Regards,

    Kristine

  • Thanks Krtistine. I will start checking this. In the meantime, if you can let me know the issues with ADA2200, please do let me know. If I can sort this out now, this will help me when I start working with the AD630 or LTC6943. I will go through the same. 

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