Regarding nRF51822 RF Performance

RE: Regarding nRF51822 RF Performance

dakoya — Tue, 16 Apr 2024 09:08:28 GMT

RE: Regarding nRF51822 RF Performance

seopyoon — Fri, 08 Apr 2016 10:10:09 GMT

Hello Kristin,

I have a question regarding balun and antenna. If I put balun, and have no antenna (leave the SE pin on BAL_NRF02D3 open) would it advertise at lease?? (with low sensitivity)

RE: Regarding nRF51822 RF Performance

bvrm — Mon, 21 Jul 2014 10:09:00 GMT

STMicro's application note AN4111 states a capacitor at the feed line for high power mode (4 dBm) with the BAL-NRF01D3 and nRF51822 QFN.

Does it also apply for the BAL-NRF02D3 and nRF51822 WLCS?

RE: Regarding nRF51822 RF Performance

FormerMember — Mon, 26 May 2014 13:23:51 GMT

Yes, the range with CEAA + balun should be similar to QFAA + discrete. In order to obtain good range with CEAA + balun it is important that you follow the reference layout for CEAA + balun.

RE: Regarding nRF51822 RF Performance

Nazmus Sakib — Mon, 26 May 2014 10:49:28 GMT

Hi Kristin.

Thanks for all your feedback. I like to ask the same ques again with some more information about my next plan.

In my current PCB I used QFAA Package and all discrete antenna components (no Balun). After tuning I achieved around 150 feet range, which is fine for my project.
In my next PCB design I want to reduce the Board size hence, I chooses CEAA Package. For Antenna I'll use Balun BAL-NRF02D3. I'll add a PI Network for tuning.

You already mentioned on your earliest message, QFAA and CEAA RF performance is same. But now I am little bit concern about Discrete components (old Board) vs BAL-NRF02D3 (new Board).

So in my new PCB (CEAA + Balun) with proper Antenna Tuning will I get similar range performance as my old PCB (QFAA + Discrete)?

Thanks in advance.

Regards.

RE: Regarding nRF51822 RF Performance

FormerMember — Wed, 21 May 2014 07:30:37 GMT

Yes, the range is the same for the CEAA (WLCSP) and QFAA (QFN) package when the antenna is tuned.

RE: Regarding nRF51822 RF Performance

Nazmus Sakib — Wed, 21 May 2014 00:08:43 GMT

Hi All.

Is the RF range performance is same for nRF51822 QFAA and CEAA packages?

Actually, I am re-designing my PCB and need to meet smaller size hence chooses the CEAA. Just a bit confused ... with proper Antenna Tuning will I get similar range performance as QFAA?

Thanks in advance.

Regards.

RE: Regarding nRF51822 RF Performance

Nazmus Sakib — Fri, 02 May 2014 15:25:31 GMT

Hi Kristin.

Thanks for all your valuable information.

I achieved around 18M range LoS finally after tuning the discrete parts.

Regards.

RE: Regarding nRF51822 RF Performance

FormerMember — Tue, 29 Apr 2014 08:28:20 GMT

Hi Nazmus,

Normally, the range should be better than 5-7m. When using discrete matching network (instead of balun), the layout of the components should be a copy of our reference layout (or as close to a copy as possible). The reason for this is that the placement and the distance between the components influence the impedance.

Regarding the questions: 1) Yes, the antenna needs an additional pi-network. All the components in the reference layout are for matching the chip to 50 Ohm. And, yes, it is important to tune the antenna.

2) It is very hard to say what range you can obtain using the Johansson balun. By using the Johansson balun, you don't know to which impedance the chip is matched, so even if the antenna is matched to 50 Ohm, there will still be a mistmatch between the chip and the antenna. It is better to use a discrete matching network, beacuse then both the chip and the antenna can be matched to 50 Ohm.

Also note that in order to obtain a stable/non-sensitive antenna, the bottom ground layer should be as large and solid as possible, because ground is the reference for the antenna; the impedance of the antenna is 50 Ohm with respect to ground.

Regards, Kristin

RE: Regarding nRF51822 RF Performance

Nazmus Sakib — Mon, 28 Apr 2014 23:50:58 GMT

Hi Kristin.

Thanks for detail reply.

I redesigned the PCB and did not use the Balun this time. I used the discrete components (L and C). With new PCB I am getting range around 5M to 7M though my expectation is at least 30M (LoS).

I like to ask,

For the RF design based on Discrete components looks like have a PI Model itself (Please see the attached). So to tune Antenna an additional PI Network needed?
I am also planning to make another design using Johanson Balun and PI Model. Do you think, its possible to get 30M Range (LoS) with proper PI Values? Sorry that I can not use the real Balun BAL-NRF01D3 due to its LGA and I am not able to do the assembly.

Yes, with WLCSP room can saved. But for assembly issue I need to stay with QFAA.

Thanks in advance.

Regards.

RE: Regarding nRF51822 RF Performance

FormerMember — Thu, 24 Apr 2014 12:45:58 GMT

Hello,

In RF Things work differently than in regular electronics due to the high frequencies, 2.4 GHz. If the system (chip and antenna) is not matched, there will be reflections in the transmission line, resulting in loss. The chip and antenna can be matched using a 50 Ohms Reference point; matching the chip to 50 Ohm and the antenna to 50 Ohm. Which components that are needed to match the chip and the antenna to 50 Ohm depends on the initial impedances. Therefore, in order for a balun to match the chip to 50 Ohm, the balun has to be designed specifcally for that chip. Since the Johanson balun is not designed for the nRF51822, it will not match the chip to 50 Ohm. That is why the balun BAL*F-NRF01D3 has to be used. The chip antenna is said to have impedance of 50 Ohm. This is however under the test conditions at the manufacturer. Since the antenna impedance depends on the environment, it will not be 50 Ohm when placed on your board. Therefore, an antenna matching network, a pi-network, is needed for tuning of the antenna to 50 Ohm. The pi-network should be placed between the balun and the antenna. By following the suggestions above, the range should normally increase significantly.

If the space on the board is very limited, it is also possible to use the WLCSP package.

Edit: There is a new balun from Johanson technology that can be used with the nRF51822/422 QFN variant, it can be found here.

Regards, Kristin