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ad8334

Category: Hardware
Product Number: AD8334
Hi ,
I have designed a Variable Gain Amplifier (VGA) circuit using the AD8334, bypassing the internal LNA section.
 Instead, I am applying an external differential signal directly to the VGA inputs (VIP1 and VIN1). The output of the AD8334 drives a THS4131 differential amplifier.
Currently, the AD8334 IC is overheating immediately upon power-up.
I have detailed my schematic layout below [or: attached the schematic details]. Could you please review the configuration and share your feedback on what might be causing the overheating?
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  • Hi Ian,


    Thanks for your feedback and recommendations regarding the AD8334.
    I will measure the supply current during power-up and update you with the findings.
    Regarding the LMD pins: We are using a total of 16 AD8334 ICs on a fully assembled PCB. Connecting a 0.1 µF capacitor to each individual LMD pin  would require adding 64 capacitors using jumper wires. Instead of connecting individual capacitors for the four LMD pins on each IC, can I short the four LMD pins of a single IC together and connect them to ground through a single 0.1 µF capacitor?
    Additionally, I will remove the clamp resistor (allowing the default limiting level to revert to 4.5 V p-p), monitor the IC current and heating, and update you tomorrow.

    Thanks and regards,
    Keshav
Reply
  • Hi Ian,


    Thanks for your feedback and recommendations regarding the AD8334.
    I will measure the supply current during power-up and update you with the findings.
    Regarding the LMD pins: We are using a total of 16 AD8334 ICs on a fully assembled PCB. Connecting a 0.1 µF capacitor to each individual LMD pin  would require adding 64 capacitors using jumper wires. Instead of connecting individual capacitors for the four LMD pins on each IC, can I short the four LMD pins of a single IC together and connect them to ground through a single 0.1 µF capacitor?
    Additionally, I will remove the clamp resistor (allowing the default limiting level to revert to 4.5 V p-p), monitor the IC current and heating, and update you tomorrow.

    Thanks and regards,
    Keshav
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