Questions on ST25RU3993-HPEV output power

[SPhun.1]

Hello ST,

We are working with the ST25RU3993-HPEV board to evaluate the RFID chip.

We have performed measurement of the output level on the antenna port and below are the obtained results:

For the internal PA:

Output level set using ST GUI / Expected output power / Measured output power / Voltage measured

0 / 20 dBm / 17.9 dBm / 0.81 V

-3 / 17 dBm / 16.064 dBm / 0.78 V

-6 / 14 dBm / 14.023 dBm / 0.69 V

-9 / 11 dBm / 11.653 dBm / 0.63 V

-12 / 8 dBm / 9.18 dBm / 0.56 V

For the external PA:

Output level set using ST GUI / Expected output power / Measured output power / Voltage measured

0 / 30 dBm / 38.52 dBm / 1.27 V

-3 / 17 dBm / 37.85 dBm / 1.27 V

-6 / 14 dBm / 35.66 dBm / 1.21 V

-9 / 11dBm / 32.86 dBm / 1.14 V

-12 / 8dBm / 30.27 dBm / 1.06 V

Are the expected output power correct for both internal and external power amplifier?

It seems to us that the obtained results from the internal PA configuration are close to the expected one but we are surprised by the obtained measures with the external amplifier.

Any idea that could help us to understand the source of error?

Best regards,

Stéphanie

[SPhun.1]

Hello ST,

Any idea that could help me make progress on that issue?

Thanks,

Stéphanie

[Bart Herse]

Dear Stephanie,

The external PA measurement values indeed do not seem to be right.

Without knowing too much about your measurement setup, I would double check the "reference power offset" and/or attenuator settings at your spectrum analyzer.

Cheers,

B