AFE5818EVM: AFE5818EVM+TSW1400EVM : Please tell me how to calculate the output power

Hello Hiroshi,

-23.862dBFS corresponds to -13.862dBm

With -50dBm input signal, the total gain in the signal path seems to be around 36dB.

Based on the AFE settings, LNA gain is 18dB, PGA gain is 24dB, Attenuation is 18dB and with open termination there is an additional 6dB.
That sums up to 30dB.

We are not sure where the additional 6 dB gain comes from.

Can you measure the peak to peak of the signal at the input of the AFE?

Hi Praveen,

Thank you for your fast response.

I understood your comments.

<My understanding>

* Full-scale = 2Vpp = 0.707Vrms = 10*log(0.707^2/50) = 10dBm

* -23.862dBFS = 0.707Vrms * 10^(-23.862/20) = 0.04533Vrms = 10*log(0.04533^2/50) = -13.862dBm

* Total Gain = 18dB + 24dB - 18dB = 24dB

* If input is not terminate then Total Gain = 24dB + 6dB = 30dB

* -50dBm + 30dB = -20dBm = -30dBFS or -50dBm + 24dB = -26dBm = -36dBFS : This is calculated value

I confirmed the input signal voltage with J6.

The result is as follows.

This input power is -30dBm because I could not measure with -50dBm. 

Input voltage in J6 is 21mVpp = -29.576dBm

EVM has a passive termination register (R24).

Therefore I think this result is appropriate.

[Q]

I confirmed it with -16dBm input.

The result is 10.14dBFS ! Why is it beyond 0dBFS ???

Do you have any gain in HSDCpro with AFE5818 configuration ?

Can you confirm it ?

Best Regards,

Hiroshi Katsunaga

Hi Pravenn,

How is the investigation going now?

Best Regards,
Hiroshi Katsunaga

Hello Hiroshi,

Have you tried with the -30dBm signal on all channels?
What does the GUI report as the Fundamental tone amplitude?

Hi Praveen,

Thank you for your response.

We confirmed your request.
The results are as follows.

<Input Condition>
5MHz, 7mVrms (-30.09dBm)

<Test Results>
Channel 1 : -11.7dBFS
Channel 2 : -11.8dBFS
Channel 3 : -11.7dBFS
Channel 4 : -12.1dBFS
Channel 5 : -12.1dBFS
Channel 6 : -12.6dBFS
Channel 7 : -12.2dBFS
Channel 8 : -12.2dBFS
Channel 9 : -12.1dBFS
Channel 10 : -12.0dBFS
Channel 11 : -12.0dBFS
Channel 12 : -11.9dBFS
Channel 13 : -11.8dBFS
Channel 14 : -11.9dBFS
Channel 15 : -12.0dBFS
Channel 16 : -11.8dBFS

Best Regards,
Hiroshi Katsunaga

Hi Praveen,

Do you have any update ?

Best Regards,
Hiroshi Katsunaga

Hi Hiroshi,

I apologize for the delay in my response.

I will need to take the data from the AFE5818EVM based on the customer settings.
Currently I am occupied on another time critical project and I will be able to get the data from the AFE5818EVM only during middle of next week.

Thanks for your understanding and patience.

Hi Praveen,

Do you have any update ?

Best Regards,
Hiroshi Katsunaga