Hello,
I'm working on a project where I need to control two HMC637ALP5E GaAs pHEMT amplifiers using a single AD7293 for gate and drain bias sequencing. I would like to ensure that only one amplifier is powered at a time, and proper bias sequencing (Vgg1, Vdd, Vgg2) is maintained per the HMC637ALP5E datasheet.
The challenge is that AD7293 provides only one PA_ON output to control VDD (typically via a PMOS switch), and if I connect it to both amplifiers, both VDDs are enabled simultaneously, which violates the required sequencing.
Here are my key questions:
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Can I safely leave VDD connected to both amplifiers (via PA_ON) as long as Vgg1 = -2V and Vgg2 = 0V for the one I want to remain off?
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What is the recommended way to switch VDD separately for two PAs using the AD7293? Would using GPIO-controlled PMOS switches after PA_ON be a valid approach?
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Is there any risk of leakage current or damage to the amplifier if VDD is on but gate voltages are in “off” states?
I would appreciate any insights or recommended configurations from the AD engineering team for this use case.
Thanks in advance.
Alireza
