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AD8132 wrong output behaviour on PCB

Category: Hardware
Product Number: AD8132

Hello,

I am designing a system with an RF front end which is converted by an ADC. I use an AD8132 as a single-ended to differential converter. 

I have tested this chain thanks to the evaluation breakboard EVAL-FDA-1 and everything was OK. But now on my custom PCB, the AD8132 output is unexpected. You can find the schematic implemented on my PCB and the input signal level (It is consistent on my new PCB and the breakboard) :

 

Unfortunately now on my PCB the output is inverted (the positive output is below the negative output and inverted), moreover the output voltage level is very low. As it can't be a schematic mistake(check during a couple of days), I assume is a PCB routing one. 

Do you have any clue why this behaviour happens? Which rules are compulsory to implement in the PCB layout to avoid any critical issues ?

Thank you so much for your future help.

Adrien

Top Replies

    •  Analog Employees 
    May 15, 2023 +1 suggested

    Hi  

    Can you provide a picture or snippet the schematic that was created? I am not an expert on this field but will contact someone that can provide answers to your concerns.

    Also, did the note…

  • Hi  

    Can you provide a picture or snippet the schematic that was created? I am not an expert on this field but will contact someone that can provide answers to your concerns.

    Also, did the note on the datasheet about Layout, Grounding and Bypassing checked and applied? You can check it on page 25 of the datasheet. Since the design is OK using the evaluation board, we can refer to it as a baseline to create the PCB design.

    And if possible, can you provide the output voltages of the circuit especially on each node if the expected voltage values are the same with the result on the calculator.

    Regards,

    JE