HMC981 driving HMC573

I am working with the HMC981 evaluation board to drive the HMC573 frequency multiplier evaluation board. I am using a supply voltage of 5.5 V and then am stepping the digital supply voltage down to around 3.4 V with a voltage divider circuit.

Based on AN-1363 page 12, there are simple diagnostics that can be done without hooking up a load to partially test the functionality of the HMC981 board. These are all correct.

When I hook up the load of the HMC 573 eval board, Vdrain drops to 0 V.

Has anyone ever worked with this combination before? What could I be doing wrong?

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If I've left out important information by mistake, please let me know and I'll get it included.

Thanks for the time.

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  • For reference, these are the connections being made to the HMC981:

    • Vdd to 5.5 V
    • Gnd to Gnd
    • Vdig to 3.5 V
    • Vdrain to HMC 573 Vdd
    • Vgate to GMC 573 Vgg
    • Gnd to HMC573 Gnd

    I am currently driving the RF in with a 5 GHz signal.

    HMC 981 Vdrain (connected with HMC 573 Vdd) drops to 0 V.

    HMC 981 Vgate (connected with HMC 573 Vgg) stays at Vneg (around -2.46 V).

    I have independently tested the HMC 573. It is working as intended when the correct voltages are applied (around 5 V to Vdd and around -1.3 V to Vgg such that Idd is 92 mA).

    Multiple HMC 981 boards (2) are behaving this way.

    Please advise if you have any idea of what is going on.

Reply
  • For reference, these are the connections being made to the HMC981:

    • Vdd to 5.5 V
    • Gnd to Gnd
    • Vdig to 3.5 V
    • Vdrain to HMC 573 Vdd
    • Vgate to GMC 573 Vgg
    • Gnd to HMC573 Gnd

    I am currently driving the RF in with a 5 GHz signal.

    HMC 981 Vdrain (connected with HMC 573 Vdd) drops to 0 V.

    HMC 981 Vgate (connected with HMC 573 Vgg) stays at Vneg (around -2.46 V).

    I have independently tested the HMC 573. It is working as intended when the correct voltages are applied (around 5 V to Vdd and around -1.3 V to Vgg such that Idd is 92 mA).

    Multiple HMC 981 boards (2) are behaving this way.

    Please advise if you have any idea of what is going on.

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