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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 ADL5535 is indeed internally matched to 50ohms on the input and output ports. Keep in mind, it's a broadband match so there will likely be some variance in the impedance profile. Table 3 provides the de-embedded s-parmaters, while the Figure 5 provides the embedded s parameter profile which includes board losses.

    I verified that the amplifier exhibits 18.5dBm at 190MHz of P1dB as specified in the datasheet using the evaluation board, signal generator and a spectrum analyzer. The source and load for the measurement was 50ohms. Please refer to my post dated Feb 6 for an explanation on how these amplifiers can exhibit higher compression levels.

    If you aren't to duplicate this result, then it's possibly a bad part or a test setup issue. Have you duplicated this result on another device?

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  • The ADL5535 is indeed internally matched to 50ohms on the input and output ports. Keep in mind, it's a broadband match so there will likely be some variance in the impedance profile. Table 3 provides the de-embedded s-parmaters, while the Figure 5 provides the embedded s parameter profile which includes board losses.

    I verified that the amplifier exhibits 18.5dBm at 190MHz of P1dB as specified in the datasheet using the evaluation board, signal generator and a spectrum analyzer. The source and load for the measurement was 50ohms. Please refer to my post dated Feb 6 for an explanation on how these amplifiers can exhibit higher compression levels.

    If you aren't to duplicate this result, then it's possibly a bad part or a test setup issue. Have you duplicated this result on another device?

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