We are trying to establish if the Vgate voltage once set at initial power should be monitored and adjusted while RF is passing.
We are going to be powering up with no RF during calibration, with Vgate bias at -4v and increasing towards 0v until the Vdrain current = 250mA.
We are debating if when running do we require to monitor the current once RF is applied or set and leave it.
It depends how you are using the part. The exact bias point is slightly less important if you are running deep in compression near Psat, where the high input power levels cause self-bias. Then quite a simple bias circuit can be effective. The bias point is more important if you are running backed off and require more linear operation. The Idq will drift with temperature, see app note, and there is also Idq change due to charge trapping which is common with GaN processes. It can be useful to have a current sense resistor in the drain and use this to adjust the gate voltage to maintain constant Idq over all conditions, assuming you can remove RF occasionally to re-calibrate Idq. If you are running RF continuously it is slightly more complex. Worth contacting appsupport@qorvo.com if you need further advice on how to bias your device, stating your company name and location.