please could you help me to explain the fact, that the ADL5535 has a higher 1dB compression point than the power supply allows?
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?
RF Amplifiers such as the ADL5355 are biased using a choke inductor at the output. The choke inductor behaves as a DC current source, setting the DC voltage at the output to Vdd, the supply voltage.This permits the device to swing between ground and 2Vdd. Hope that clear things up.