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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
  • The datasheet states "Input and output internally matched to 50 Ω", so I've naively connected the input to a matched source and the output to an Agilent spectrum analyzer directly, and the measured results are:

    However, I will run some simulations to check if the "not so 50 ohm" matching could cause the difference...

Reply
  • The datasheet states "Input and output internally matched to 50 Ω", so I've naively connected the input to a matched source and the output to an Agilent spectrum analyzer directly, and the measured results are:

    However, I will run some simulations to check if the "not so 50 ohm" matching could cause the difference...

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