HMC863ALC4 Performance issue: Output power 3 dB less than specified


we currently design a radar using HMC863ALC4.

The problem is that we could not get the spefied output power. It is about 3 dB less.

@24GHz with 6V we should see 28dBm bt could only measure 25dBm.

Is anybody out there who has experience with this device?

Is the a reference design, to get the specified values?

Any comment is highly appriciated!



  • +1
    •  Analog Employees 
    on Sep 21, 2018 6:54 PM

    Hi WiW,

    What is your quiescent drain current set to? With Vdd=6V and Iddq set to 150 mA or greater, you should be able to achieve much closer to RF Pout=+28 dBm than the +25 dBm you measure. Do your DC bias supplies have adequate capacity to allow their current magnitudes to increase in response to increasing RF Pin drive levels? (As shown for Idd on the data sheet plot below, Power Compression @ 25 GHz). Are you driving RF Pin at a fixed power level or are you able to increase RF Pin to see if Pout will increase in response?

    The plot you've attached is for Iddq=350 mA at an Operating Temperature of +25C (defined at the ground paddle). Could the ground paddle of your part be at a much higher temperature? Are you using a heat sink?

    The "reference design" would be the Applications Circuit shown on the data sheet, implemented on a PCB like that of our EVB. The HMC863ALC4 product page contains a link to the EVB's gerber files, which include complete stack up info, material details, etc. See gerber files at link below:

    That gerber package should serve as a useful reference point for implementing a successful design.