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PHEMT bias sequencing circuit

Question asked by yckim on May 1, 2016
Latest reply on May 9, 2016 by kkaya


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?