I'd like to use the HMC980 to control the power on/off sequencing of my HMC7357 but I am not sure if I want the constant drain current feature of the HMC980 since the drain current can go as high as ~1350 mA. The questions I have are:
1 - Is there a bias sequencer part that holds Vgg steady and lets Idd very with RF drive power?
2 - If I use the HMC980, what bias current do I set it to? The datasheet is specified for an Idq of 1200 mA, but in the plots for power compression for the HMC7357 (pages 4-5 of datasheet) the drain current is not constant - implying that the device was tested under constant gate voltage.
My application is very sensitive to efficiency and linearity, so if I want to operate at 8 GHz and at the P1dB point, the power compression curve says drain current needs to be >1300 mA.
What I really want is a constant gate voltage controller that provides the correct power sequencing for a GaAs pHEMT, such as the HMC7357, but I could not find one of those, and I'm hesitant to use an active controller that varies gate voltage to hold a steady drain current on a device that has been characterized under a constant gate voltage.
Any advice out there?