NRF5340 - QSPI RF performance issue from ERRATA

RE: NRF5340 - QSPI RF performance issue from ERRATA

Kenneth — Wed, 13 Sep 2023 10:12:15 GMT

[quote user="herbata"]Is this correct?[/quote]

The short answer: Yes

The a bit longer answer: Yes, but likely the reduction will be between -95 and -98dBm across the channels for 1Mbps, because it's not a flat 3dB degradtions across the entire 2.4GHz band, you can consider 3dB as the worst number.

Kenneth

RE: NRF5340 - QSPI RF performance issue from ERRATA

herbata — Wed, 13 Sep 2023 09:26:27 GMT

So just to confirm based on NRF5340 datasheet sensitivity list:

• -98 dBm sensitivity in 1 Mbps Bluetooth Low Energy mode
• -104 dBm sensitivity in 125 kbps Bluetooth Low Energy mode

would become when operating QSPI + BLE simultaneously with the 1.8V supply:

• -95 dBm sensitivity in 1 Mbps Bluetooth Low Energy mode
• -101 dBm sensitivity in 125 kbps Bluetooth Low Energy mode

Is this correct?

RE: NRF5340 - QSPI RF performance issue from ERRATA

Kenneth — Tue, 12 Sep 2023 14:26:05 GMT

Hello,

So you are referring to this errata that have two workarounds:
https://infocenter.nordicsemi.com/topic/errata_nRF5340_Rev1/ERR/nRF5340/Rev1/latest/anomaly_340_133.html

"Use one of the following:

Use VDD voltage between 1.7 V and 2.0 V to limit the degradation of RX sensitivity to 3 dB across the channels.
Ensure that QSPI and radio are not operating concurrently."

Your question is about how to understand the first workaround regarding degradation of RX sensitivity:

If your supply voltage is between 1.7V and 2.0V the sensitivity degradation will not be more than 3dB during QSPI usage, if your supply voltage is higher than 2.0V the sensitivity degradation can be higher than 3dB. Have in mind that the degradation is not flat across the 2.4GHz band, so if you are making a BLE device it may not be noticable by the user that you have sensitivity degradation on some of the channels in the 2.4GHz band during QSPI usage, since the device will frequency hop continously and thereby indirectly mask out that QSPI may be causing increased packet loss at given times and channels.

Kenneth