What is the purpose of Carrier cancellation and Log amplifier in RF chain.

[Sumeet66]

Hello ST community,

What is the purpose of Carrier cancellation circuit and Log amplifier in RF chain? We are making a standalone circuit design on our own pcb, Do we need to include that in our design?

Thanks and Regards,

Sumeet Patil

[Bart Herse · Accepted solution]

Hi,

the carrier cancellation is used to suppress the carrier which leaks into the receiver (Self-Jammer).

It is strongly recommended to implement this part of the circuitry.

Log amplifier: If you are referring to the power detector which is connected to the 20 dB directional coupler - this could be left out, it is not necessary.

Cheers,

B

[Sumeet66]

Thank you for the reply,

So, we can omit 20 dB coupler also?

[Bart Herse]

​Exactly, the 20 dB Directional Coupler could be removed as well in case the power detector functionality is not implemented.

Cheers,

B

[Sumeet66]

Hi Bart,

Thanks for response, I have a question what is the role of power detector? Is it used to measure receive power or transmit power?

Another question I have, we want to introduce fail safety mechanism, such as our MCU should be able to diagnose where in the RF chain there is failure?

For example, we want to check electronically whether power amplifier has failed or not? Can you give us some ideas, on how to diagnose RF chain issues.

Look forward to hearing from you.

Thanks and Regards,

Sumeet Patil