Hi Team,
we are using TGM2635-CP in our design. we are using it for pulsed signal.
The gate voltage for the device is continuous and the Drain voltage is pulsed.
The datasheet says the absolute maximum input power can be given is +33dBm at “85°C , VD = 28 V,Pulsed; PW = 100 us, DC = 10%”.
can we know what is the tolerable input power limit when Device’s drain voltage is off(Gate voltage is present and Drain voltage is zero)?
Thank you,
Obulreddy B
Director-Payload Electronics
Piersight Space
This maximum input rating really applies when PA is biased, this is how it was derived from overdrive tests. You should be operating with input power below this, typically 28dBm. Best practice is to pulse the RF input as well as the drain, as shown in this app note:
https://www.qorvo.com/products/d/da008462
Hi Chris_LS,
Thank you for the reply.
in our design, there is a possibility that input RF will be available at the device but the Drain bias is not(we are working on failure analysis of our circuit). in that situation what happens to device?
The input RF will be well with in +28dBm.
This is OK. This shouldn’t cause any reliability issues. As the app note suggests you can prevent performance issues like transients when you pulse the RF as well as the drain.
Hi Chris_LS, Thank you for the reply.
we have one more query.
we are combining two TGM2635’s outputs by a power combiner. and the power combiner does not have good isolation characteristics.
if PA-1 drain is off and PA-2 drain is ON. some power will be available at the PA-1’s output port(due to power combiner isolation issue).
what would be the limit on reverse power at output port which device can handle?
Note: finally we are combining 8 devices to get required power. I have explained a example scenario above.
Thank you,
Obul.
This isn’t something that is characterized. Do you know the combiner isolation (worst case)? Lack of isolation could cause other issues like even mode oscillations.