I’m currently working with the QPA1014 and following the recommended biasing procedure. However, I’ve noticed something that seems off and wanted to ask for your input.
When I set the gate voltages for Vg1 and Vg2 to -2.7V as specified, I’m only seeing about -45 mA on the power supply. This seems lower than expected to me.
Do you have any suggestions or insights on what might be causing this? Is this current within the normal range for initial gate biasing, or could it indicate a potential issue?
Hello. The ideal gate voltage setting for proper Idq (Drain voltage without RF input) can vary quite a bit with GaN, both lot to lot and within lots. This is why we specify a bias-up procedure to adjust the gate more positive until the proper Idq is reached:
I had an incident that prompted this question when following this bias up procedure. When I followed this procedure and I set the gate voltage to -2.4V after -2.7V this caused a current spike and damaged my device.
Could you help me understand the right ramp rate V/s that is safe to make sure I don’t damage the device? Is there anything else not in this procedure that would safe guard another event like the one I experienced above? Is there a way to get a sample of this device so that I can replace the one I damaged?
Also, could you help me understand
the proper procedure for drain pulsing the power amplifier?
Do I need to remove RF and reduce gate voltage back down to -6V before pulsing the drain of the PA or do I just follow the biasing up procedure and then I can pulse the drain from 28V to 0V without damaging the device?
Hello. Sometimes one can have DC bias oscillation if the test leads are long. This will cause the Drain current to quickly shoot up and possibly damage the part. Best way to avoid this is to shorten the test leads and/or add a 47 uF capacitor (in proper polarity) to the gate bias leads or at the EVB itself.
The DC bias oscillation will come up quickly as gate bias is made more positive. It is a short-term, usually damaging event. Please email appsupport@qorvo.com for continuing support.
