nRF54l15 EVM

[zz19930722]

Hello, I have developed a module using 54L15 and am currently measuring its RF performance. On Rohde & Schwarz instruments, I have observed numerous test results regarding EVM, but I am unsure which parameter on the instrument corresponds to the EVM specified in the chip datasheet.

As shown in the figure above, the EVM parameter in the datasheet is 2%rms, but my measurement results are: Abs.RMS EVM Overall (%)：13.39 %rms, Off.RMS EVM Overall(%) ：2.154 %rms. Both seem to exceed the specified limit. Which parameter should I record?

[Simonr]

Hi

The 2%rms EVM in the datasheet is not a maximum limit, but rather the typical expected EVM value across all nRF54L15 SoCs. So 2.154%rms should be well within what's expected here.

It is the offset value and not the absolute that should be used since you're measuring the OQPSK (Offset Quadrature Phase Shift Keying) modulation here. You can find some more information on OQSPK modulation here: https://www.everythingrf.com/community/what-is-oqpsk-modulation 

Best regards,

Simon

[zz19930722]

Thank you for your response. In practical terms, is it correct that the standard for this modulation scheme is 35%rms?

[Simonr]

Hi

IEEE 802.15.4, which uses O-QPSK modulation scheme at 250kpbs. Support for a given modulation scheme is added in the PHY later, but which modulation scheme to use is optional.

Best regards,

Simon