Post Go back to editing

HMC783(764,765,807) userguide error?

I'm using HMC783 in my design recently, but I find the user guide of hmc783 is incompatible with it, while it is similar to hmc700 about register discription on Reg 0Dh GPO_SPI_RDIV Register (page A-21). The user guide mentions D1 & D0 pins, but HMC783 does not have these pins. I'd like to watch the REFDIV output signal on LD_SDO pin to check whether the chip is working or not. So can anyone give some advice about HMC783 ? Thank you very much !

My email is

  • Hi there,

    You are correct in that these pins which appear on the HMC700 stand alone PLL are not available on the HMC783LP6CE Integrated VCO/PLL synthesizer. The user guide is wrong. Since it sounds like you're not using the evaluation board, I recommend reading back REG 0Fh, should be '1' if locked. Can also view output on spectrum analyzer by probing RFout (and / or REF input) with 50Ω 'sniffer' made from an SMA with a short piece of coax with exposed center conductor. You can use the attached 12GHz, 50MHz REF / PFD Integer mode register file as a starting point, simply adjust the settings based on your reference & PFD frequency.

    Best Regards,

  • Hi Marty,

    It is exciting that the chip now can output a signal with the frequency I need with the help of the register file you provided. Thank you very much!