I'm designing with LNA to receive a BW = 8 MHz signal (channel BW = 25 kHz), see block diagram:
There is a case where an in-band channel signal (or blocker) which is strong enough saturates the LNA input and then degrades the linearity of the channel of interest.
To avoid this case:
I plan to use a coupler + power detector to measure the in-band power in this case and attenuate the LNA input power in case the blocker is too strong, so that the LNA operates in the linear zone (this also protects the LNA in case the maximum input rate is exceeded).
Maybe use an RF limiter instead of attenuator to protect the LNA input. My question here is: when the in-band blocker is attenuated by the limiter (the limiter is not linear any more), what about the useful signal (at another channel)? Does the useful signal pass through the limiter normally or does it also suffer from the non-linearity of the limiter?
Are there other ways to avoid high-power, in-band blockers?