nRF51 conducted power

[travisf]

I measured the conducted power on the PCA10028 demo board and get ~2dBm out when I set the output power to +4dBm. It appears the PCA10028 is using a discrete balun. Is 2dB expected through the balun? Is there any data for the IC balun used in the reference design for expected loss when connected to the nRF51?

I'm using the radio_test.c in the SDK to setup the radio for CW.

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edit: numbers over frequency for PCA10028 MHz TX power conducted (dBm)

• 2400 1.61
• 2410 1.73
• 2450 1.90
• 2480 1.79

[travisf]

I saw in the datasheet for the balun that 2dB is expected for insertion loss.

[Øyvind Karlsen]

Hi,

Have you accounted for cable loss? The cable loss for these measurements in our lab is typically around 0.5dB.

Some information is available through the user guide for the development kit. Be aware that the insertion loss of the discrete balun is dependent on component variations. From the information found in section 5.8 on RF measurements in the user guide we can see that the typical loss of the coaxial connector and associated probe will be around 1dB at 2440MHz. If you then add the cable loss you will see numbers that more closely resemble the expected 4dBm.

A quick overview of IC baluns can be found here under development tools and software. A quick look at one of the baluns that Johanson provide for the QFN48 package shows an typical max insertion loss of 0.9dB.

Hopefully this makes things a bit clearer. Best regards,

Øyvind