I'm system engineer, so don't know well about PHEMT or HEMT chip.
I'd like to use HMC598 and HMC-ALH382, HMC-ALH476 like doubler or AMP.
These chips are required some bias sequence.
You can find PDF file about bias
//Design and Implementation of a Bias Sequencing Circuit for the HMC463LP5 Low Noise Amplifier//
that circuit is method how to make proper bais sequence.
They say VGG should be turned on than VDD. I understood it and It did good.
But, when VGG is turned off, is it okay?
I think VDD will be turnd off after VGG. It may be problems.
But that application note notice only tuned off speed by using VDD' capacitor.
Now, I want to know correct bias sequence.
Could I ignore bias when chips are turnd off?