What is the difference between P1dB parameter and output power parameter ?

[amirke]

Are they the same parameter ?

 

[OldRFguy]

For small signals the output of an amplifier will simply be the input signal level plus the gain. Due to the limitations of the device itself, any matching networks around it, and the power supplies it is running from, a point will be arrived at where the input signal can be increased but the output level is no longer simply the input level plus the small signal gain; the amplifier is now begining to operate in compression. When an increasing signal level has made the small signal gain drop by 1dB the amplifier has reached the P1dB point which, for a small signal amplifier is often regarded as its operating power as above this level distortion will rise quite rapidly.

In many older books you will often see a rule of thumb that gives the IP3 or third order intercept of an amplifier as approximately 11dB above the P1dB point although for modern devices this figure can now be much higher; the Triquint WJ1510 for example has a P1dB of 20dB and an IP3 of 43dBm.

I hope this helps.