HMC997 and HMC565 Demo-board Capacitors


I am experiencing some differences between my PCB's (replicas of the demo boards) using these integrated circuits and the demo board that I ordered from Hittite. As these differences are the same and occur on the same bands (approx 17 GHz) in both HMC997 and HMC565, I am concluding that my experience is due to different capacitors.

I would like to know, if possible, what are the manufacturers and models of the 100 pF RF choke capacitors used in both these demo boards.

P.S.: The transmission lines impedances (in CPW) were validated using HFSS. They were adjusted to be 50 Ohm.

Thanks in advance,

Hugo Santos

  • Hi,

    Speaking for both EVBs,

    You can use either of the following or any similar capacitor, for those 100 pF CAPs.

    Yageo CC0402JRNP09BN101

    Murata GRM1555C1H101JZ01D

    Kemet C0402C101J5GACTU

    I also attached gerbers for both EVBs. Performance degradation at those frequency can be due to PCB layout. Try to use PCB layout architectures as close to ADI PCB as possible to obtain performance shown on the DS plots.



  • Hi Kagan,

    First of all thanks for your quick answer. I also suspected the PCB layouts as they are not an exact replica of the EVBs. However, the capacitor placement is very similar to the EVB and the length from the IC pins to the capacitors is practically the same as the one of the EVB. I think that this small difference doesn't explain the weird behavior in respect to the demo board. The capacitors beeing used are Kemet C0402C101J5GACTU just as you recommended.

    Kind Regards,

  • The gerbers can be for the newer PCB version.

    I sent you an email for further details of your application setup.