Question about P-1 in a LNA design with negative feedback

[jeanjean]

question about P-1

when i design a lna using negative feed back ,the P-1 will be worst than don't using it.

i don't know how to explaination it .

anyone have any datum about it ?

thank you !

 

[vfone]

Re: question about P-1

I think somewhere is a misunderstanding. Adding feedback (or degeneration) to an RF amplifier will simultaneously increase P1dB and IP3 (reduced voltage gain, decrease distortion and increase the bandwidth). Negative feedback also has the advantage of making amplifier voltage gain more dependent on resistor values and less dependent on the transistor's characteristics.