RF Amplifier Design Help

[sreekdr729]

Hi,

I am designing an RF amplifier for the ISM band for a specific project. The idea is range improvement. We attached a CMX90A004 evaluation board to our transceiver module and we achieved increased range. But the same system with the RF amplifier while receiving back signals is attenuating the RX signal. I have turned off the RF amplifier module by driving low to the CONTROL voltage, while in RX mode.

Q1. Is this an expected behavior or a design issue?

I am planning to use an RF SWITCH to switch between the TX path and the RX path. It may work.

Q2. Please suggest the right design approach while considering an RF amplifier for LORA system.

 

[aliarifat794]

To improve sensitivity and range you can add an LNA in the RX path.

 

[danadakk]

Is your RF switch decoupling the PA output when in Rx mode ?

If you are powering it off to rely on disconnect use your Nano VNA and
look at PA output Z to see if its a passive matching network solution,
hence powered off probably still presents 50 ohms onto antenna loading it.