Hi, I am looking forward to cascade two QPA9127, I have designed a prototype based on the reference design in datasheet. Can i connect the two prototype boards in series and get cascaded configuration? Is there any open source design for cascaded operation that i may follow?
Regards
Nitin Kumar
Hi Nitin,
You can connect two of the QPA9127 evaluation boards in series for more gain, but can you clarify what is the application and spec requirement? Also, we do not have an open-source design cascading two QPA9127 devices.
Hi Liz,
Thank you for the response. I am working on a video transmitter design, it requires output power of 33dBm. I am using QPA9127 as a pre-driver, since the baseband output is around -20dBm, i wish to use two QPA9127 to bring output level around -15dBm and then use another PA in cascade to get 30dBm.
Yeah, you can cascade the QPA9127 boards in series, but just make sure the output of the first one isn’t too high for the second’s input.
ok thank you for the suggestions.
Can you update us on your progress?
Hi @katy443,
I am using custom boards for QPA9127, when cascading two of such boards i am observing a loss of 2-3dBm in output power. e.g. i input -33dBm into first stage, the output is -12.2dBm, this goes into 2nd stage, a 20dB attenuator is used after 2nd stage so that power measurements may be done safely. The output after the attenuator is -14.7dBm.
I’d check the impedance matching between the boards, sometimes that’s enough to cause a little drop