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?
If I've left out important information by mistake, please let me know and I'll get it included.
Thanks for the time.
For reference, these are the connections being made to the HMC981:
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.