RE: nrf52832 impedance matching with VNA

Jared — Mon, 11 Oct 2021 13:37:21 GMT

Yes that should be correct.

RE: nrf52832 impedance matching with VNA

bstarbuck3 — Fri, 08 Oct 2021 14:22:38 GMT

Hi Jared, thank you for your quick response. I will restate Q3 and Q4 more concisely. On the final prototype PCB, to verify and measure the impedance, do I solder the VNA probe at the point that I want to know the impedance and then also solder the other end to the PCB ground plane?

RE: nrf52832 impedance matching with VNA

Jared — Wed, 06 Oct 2021 14:13:07 GMT

Hi,

[quote user=""]Q1) Should this be 0.8 pF and 3.9 nH or 1.0 pF and 3.3 nH?[/quote]

It depends on the package. For QFN it's the former, for WLCSP it's the latter.

[quote user=""]Q2) At the end of this trace and just before the antenna, should be a pi matching circuit?[/quote]

The kind of the matching network depends on the antenna and what the antenna producers recommend. But in most cases we suggest a Pi network. Yes, the placement is correct.

[quote user=""]

Finally, I need to evaluate this design with a VNA for impedance matching.

Q3) Where exactly do I measure with the VNA? Just after the nrf52 pin but before the nrf52 capacitor and inductor matching components? Or just after the rf trace but before the pi matching? Or both?

The PCB and traces are quite small and I don't see how I could possibly measure this.

[/quote]

See this thread.

[quote user=""]Q4) Should I make another PCB just for measuring this consisting just of everything coming out of the antenna pin on the nrf52? Or just everything from pi matching and antenna.[/quote]

I didn't quite understand this question. The PCB that you're tuning should be the final prototype that contains everything that is going to be included on the board in addition to the enclosure.

best regards

Jared