Hello, is it safe to leave unused output (for example VR2) of HMC1060 floating? Or should I keep the capacitor between VR2 and RD2 (for stability)?
All unused outputs require a 10nF capacitor to ground. No feedback capacitor between VRx and RDx is required for unused outputs. For example if you do not require VR2 connect a 10nF capacitor from VR2 (pin 11) to ground.