topic Re: KW38 BLE RF output power level in Wireless MCU

KW38 BLE RF output power level

rmzj — Thu, 14 Jul 2022 08:47:38 GMT

Hi Sir,

We measured KW38 BLE RF output power level is about 3.1dBm at ch39(2480 MHz) after tuning rf matching. But I see KW38's output power level can be up to 5 dBm with LDO-HF bumped.

I am not sure if LDO-HF bumped is enabled or not on our Board. Could you please tell me how to enable LDO-HF bumped function on KW38?

HW: MKW38

Software: a binary code (connectivity software from SDK_2_6_15_FRDM-KW38) was loaded into KW38.

Re: KW38 BLE RF output power level

jasonchiang — Sat, 23 Jul 2022 15:12:38 GMT

Hi Robin,

Sorry for late.

I checked connectivity S/W, GENFSK_ConfigurePower inside genfsk_utils.c. I saw BumpPaPowerUp function enabled for Hi Power. We have Hi Power 31 and Lo Power 31 command. Just check if you perform Hi Power 31 from your console below.

In parallel, I am working to clarify if any H/W modification required. I will give you update soon.

Re: KW38 BLE RF output power level

rmzj — Mon, 25 Jul 2022 07:23:19 GMT

Hi Jason,

Measured same RF power level about 3.1 dBm whether to set Hi power 31 or Lo Power 31.

Re: KW38 BLE RF output power level

jasonchiang — Tue, 26 Jul 2022 14:37:21 GMT

Hi Robin,

Thanks for reply.

Your results is not the same as mine here. I can got the test results below using FRDM-KW38.

Hi Power 31 mode, I got around 3.3 dBm output.

Lo Power 31 mode, it is 1.6dBm output

May I have your help to test again to verify the attached bin file generated from my side and see if there is different output level using Hi power / Lo power mode for your board ?

I am still working with our expert internally the way of achieving 5dBm output power either from H/W or S/W viewpoint.

Re: KW38 BLE RF output power level

rmzj — Thu, 28 Jul 2022 02:02:49 GMT

Hi Jason

We tried to download your bin file to another board which we didn't fine tune the matching.

No difference between Hi power 31 and Lo power 31

And our KW38 is set to bypass mode. any impact for RF power?

Re: KW38 BLE RF output power level

jasonchiang — Fri, 29 Jul 2022 13:38:57 GMT

Hi Robin,

Sorry for late. See my setup and test results below.

4.5dBm output power at SMA connector port. Overall loss (from RF pin to SMA connector) = 0.67 dB, So 4.5+0.67=5.17 dBm. It meets typical output 5dBm of KW38 specification. Please be noticed that 5 dBm typical is KW38 RF pin output. I also attached the bin file which I tested and the FRDM-KW38 board setup(default setting is buck mode) for reference. From the results, it may say LDO-HF bumped is enabled at NXP frdmkw38_connectivity_test project file.