limiter for -25dBm?

You could amplify, and limit at higher power.

One more point, after amplification and limiting do not forget to attenuate to the required level.

Is there any other way?(without increasing power)

dear 7rots51
limiter is my chalenge too.and i gona make it.i think one important point that you have to pay attention is frequency.and the other is your device where limiting take place through that.for example i have seen some waveguide port.maybe you gona make some coaxial one?
ask this question and then we can go ahead step by step

my frequency is 1-2GHZ.what solutions for this freq band exist?(except limit at higher power)

dear 7rotes51
do you have any special configuration?
for example do you like to design your limiter for waveguide port or for coaxial?

Assuming you have a way of detecting the modulation, a low power oscillator will lock to an incoming signal over a limited bandwidth and thus provide a constant output level. This is useful for FM but not AM.

modulation is FSK.

to young.microwave.eng:
no.

Limiters are not applicable to AM but PM and FM due to envelope issues.
AGC is the solution for AM.
May I know the end application?