HMC576LC3B's 1, 3, 7, 9 pins and bottom pad are ground. So these pins should be connected PCB's ground. Also It's described in datasheet.
However, evaluation PCB's GND pins don't be connected PCB's ground, like open pins. I'm confused what is the right way.
Anyone help me thank you.
On the HMC576 (as well as the HMC507 which someone also inquired about recently) there are no internal connections to the N/C pins so they can be left floating (soldered to a pad of course)…