MRFX1K80H 174-230 MHz VHF Doherty with Vertical Planar Transformer

[Antoine]

Hello,

In the reference design "MRFX1K80H 174-230 MHz VHF Doherty with Vertical Planar Transformer", I'd like to know if you can provide some details about the planar transformers T1 and T2: what is the impedance ratio of the 2 planar transformers used, and do you have some source or link that I can read in order to better understand how it works. I can't find some litterature on the web about planar transformer in high power applications...

My goal is then to tune this reference design board in order to cover a lower frequency range (and so I assume that I will need to design some new transformers).

Thanks for you help, and best regards,

Antoine

[Brooke]

Hi Antoine,

Could you found the way how to simulate the planar transformer with ADS or AWR?

I am searching document for this topic at the moment, but there is limited literatures on the website.

You can contact me with private mail: brooke.liu@iclound.com.

Best Regards,

Brooke

[Antoine]

Hi Brooke,

Yes I succeed in doing some ADS simulations: the dxf of the vertical planar transformers are available for download on the NXP website, so I use it to perform some EM simulation.

Here are what I obtained for the 2 vertical planar transformers used in this design:

So as we can see both are 4:1 impedance ratio transformers.

Hope this helps,

Best regards,

Antoine

[Brooke]

Hi Antoine

Thanks for your reply.

I used your same way for simulation the 4:1 planar balun.

Download the DXF file from NXP website, and import into ADC for setting up the EM model. And then simulation to obtain impedance.

Would you find the way to optimize the size of the balun? I want to use small bandwidth of this kind balun. While the reference design from NXP side is a little bit large for us.

Thanks again for your time.

Best Regards,

Brooke

[ErikaC]

Hello,

Unfortunately, we have no any reference documents from NXP describing designing planar baluns. Please refer to Ampleon application note describing very similar design with the BLF578:
https://www.ampleon.com/search.html?q=AN10858

Hope this helps.

[Antoine]

Hello Erika,

Thanks for your feedback, and for the link, it's interesting.

Concerning the MRFX1K80H 174-230 MHz VHF Doherty with Vertical Planar Transformer reference design, do you just know the impedance ratio of the vertical planar transformers ? Maybe 1:1, or 4:1 ?

Thanks !

Antoine