Issue with Current Measurement During Carrier Transmission on nRF7002DK_nRF5340

[Germain B]

Hello, I have an issue regarding the current measurement of my nRF7002DK_nRF5340. I am trying to measure the current consumed during the transmission of a carrier on a Wi-Fi channel (with oscilloscope). I am using the example: Wi-Fi: Radio test (Multi domain).

However, by following the current measurement instructions https://docs.nordicsemi.com/bundle/ug_nrf7002_dk/page/UG/nrf7002_DK/hw_measure_oscilloscope.html

When I remove the jumper, the carrier disappears; the board stops transmitting. Which is obviously annoying, the initial goal is to know the consumption during transmission.

I followed the instructions correctly, placing a 10-ohm resistor on the footprint R91, and there is no USB power supply.

Did I miss something ?

[Susheel Nuguru]

When you remove or cut the jumper on R91 you are actually disconnecting the VBAT rail from the nRF7002 on the DK board and that makes the radio lose its power so the Wi-Fi carrier just disappears. Your 10 Ω resistor was simply too large and caused so much voltage drop that the module shut off. Use something much smaller, like 0.1 Ω or 1 Ω, feed the board from an external 3.3 V supply once you’ve cut R91, and measure the voltage across the shunt with a differential or math setup on your scope. That way you’ll see the true transmit current waveform without killing the carrier.