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ADL5535 1PdB - 1dB Compression Point Unterstanding

Hi Folks,

please could you help me to explain the fact, that the ADL5535 has a higher 1dB compression point than the power supply allows?


Example:

1dB P1 = 18.6dB as lowest in statistic, according to Fig.11. of the datasheet.

 

18.6dB is 72.44mW into a 50 Ohm load.

U = SQRT (P*R) = SQRT (72.44mW * 50) = 1.9Vrms

Upeak = 1.9Vrms * sqrt(2) = 2.69V


To run Upeak-peak the Voltage swing is: 2 * 2.69V = 5.38V.

This should be the voltage on the 50Ohm termination.

If we consider the internal driver has a 50Ohm series termination, the driving voltage must have 10.77V. Considering no extra headrom for the transistors to drive the load.


How can the outputpowerlevel of at least 18.6dB be explained?

Is the datasheet correct?


Thanks.


 

Parents
  • Based on S22 from the datasheet at 1000Mhz, it looks to me like the real part of the output impedance for the ADL5535 is 31.5 ohms, with a reactance of -4.9 ohms. I have to admit to being a little confused here since the S-parameters are apparently in dB format and the the tabular values for S22 magnitude do not seem to correspond to the plotted values for return loss in the datasheet, particularly at the lower frequencies.

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  • Based on S22 from the datasheet at 1000Mhz, it looks to me like the real part of the output impedance for the ADL5535 is 31.5 ohms, with a reactance of -4.9 ohms. I have to admit to being a little confused here since the S-parameters are apparently in dB format and the the tabular values for S22 magnitude do not seem to correspond to the plotted values for return loss in the datasheet, particularly at the lower frequencies.

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