Is there a way to calculate when an amplifier will block by knowing its IP3?
If not, is there any way to calculate the blocking capabilities of an RF amp,
such as an LNA?

Thanks!

Mike

s there a way to calculate when an amplifier will block by knowing its IP3?
If not, is there any way to calculate the blocking capabilities of an RF amp,
such as an LNA?

Mike-

I understand the IP3 (third order intercept point?) is related to
intermodulation. This concerns when a signal just starts to interact with
another, generating additional signal(s). IP3 certainly relates, but I doubt
it is sufficient to calculate the point where blockage occurs. Depending on
linearity, intermodulation can occur well below a level where the amplifier is
blocked.

Blocking is the extreme case. An amplifier is blocked and stops amplifying
when it is saturated. One might analyze this condition by considering the
maximum peak-to-peak output being equal to the supply voltage. Saturation
occurs when an input signal's peak-to-peak voltage exceeds the supply voltage
divided by voltage gain. Any higher input will produce the same peak output.
In the process, gain for a weaker signal decreases as the stronger signal
approaches saturation.

In the case of an LNA, subsequent stages can be blocked even though the LNA is
operating in its linear range.

Does this help?

73, Fred, K4DII