What matching components should be used for the 5x5 QFN package?

[rezarethink]

According to the datasheet, the smaller 5x5 QFN (ESP32-D2WD) part the output impedance is 35+j10 which is different than the larger 6x6 package. What matching components would be recommended that part vs the old part (which has a different output impedance)?

Also, I noticed that there are no matching components on the sparkfun esp32 board but it works fine. Why is that?

Thanks,
Reza

[Franco]

Hi Reza, in the Sparkfun esp-32-thing schematic, I can see the matching circuit. https://cdn.sparkfun.com/assets/learn_t ... ematic.pdf
As far as the ESP32-D0WD you can use this circuit.

ESP32-D0WD.png (13.42 KiB) Viewed 15297 times

Let us know.

[Lucas.Hutchinson]

You should use a PI matching network (like that shown in the post above).

However please bare in mind that you will probably have to tune this network by altering the values of the conductors and capacitors depending on your circuit layout and antenna choice.

[rezarethink]

Although the sparkfun schematic might have those components in it, they only populate a small cap on the PCB, which is strange. Also, the sparkfun uses the 6x6 package and we use the 5x5 which has a different rated output impedance. There are references for the components used to match the 6x6 but nothing for the 5x5.

My main question is - what's a good starting point for matching components for the 5x5mm package?

-thanks in advance-

[Franco]

Hi Reza, the schematic I had posted before was from an early version of ESP-WROOM-32U. The datasheet http://espressif.com/sites/default/file ... eet_en.pdf has just been published and you can check the final schematic on page 15
[img]

ESP-WROOM-32U Pi filter.png (81.33 KiB) Viewed 15157 times

[/img]
I hope this helps.

[WiFive]

So wroom32 is switching from tapped capacitor matching to pi matching?

[Franco]

I checked the ESP-WROOM-32 (with PCB antenna) and the schematics on page 17 shows a similar Pi matching circuit.

[WiFive]

WROOM-32 has tapped capacitor matching circuit, so does WROVER.

WROOM-32D/U has pi circuit.

Interested to know reasons and effects.

[Franco]

On this document it is stated "feature optimized antenna and RF performance" https://www.linkedin.com/feed/update/ur ... 1742822400

[WiFive]

That is interesting so will there be an update to wrover modules too?