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oscillation of HMC447

Category: Hardware
Product Number: HMC447

Hi all,

    The hmc447 is not working properly on my board when 26G input and 5V power are well supplied,there is a large signal output at 5Ghz around when i checked the output.And the signal is hung and moved which is like self-oscillation.What's worse, the part will no longer work normally when this happen.That menas i have to replace it with a new part if i want to get to work properly.

I have some questions about  hmc447:

1.Does it need a DC-blocked capacitor when there is  a hmc519 before hmc447? i see the output of hmc519 is DC blocked internally from the datasheet,so i didn't add a dc capacitor at the input in my design.

2.when the hmc447 worked abnormally,i checked the input impedance of hmc447 which is 1.5 ohm instead of 50 ohm.Which may cause this happen?


  • Hi,  It sounds to me like the input experienced electrical overstress.  The ESD rating on this device is not very high either (class 1A).  It could be that this was an ESD event during assembly.  Or it could be due to some interaction with the HMC519 after assembly.  It would be a good idea to send the bad unit into ADI's failure analysis and see if they can distinguish the failure mode.  To do this you would need to contact your local sales support to start this process.