amplifier not band-limited in cascade

[Xavipersonal]

When i verify the cascaded amplifiers with ADS S-parameter simulation, i get a nice curve showing that i obtain 60 dB gain at the IF frequency, which is what i want.
However, for real implementations 60 dB of gain can become a problem if the amplifier is not band-limited, i.e. by having filters in between cascaded stages. I dont undertand why can not band-limited amplif. became a problem?


thanks in advance

 

[BigBoss]

There is some mismatch between the stages.That's why you loose the gain..

 

[Xavipersonal]

but all the amplifiers have its own matching network.

 

[WimRFP]

Hello,

When you are using fast components and your impedance matching is broadband, you might get parasitic oscillations (far away from the intended frequency band) due to feedback from output to input.

Depending on the processing of the IF signal, out of band noise may disturb further processing. When filters in between, out of band noise is suppressed.

When there are other (strong) signals present around the IF amp, these signals may result in considerable output (at the IF amp), this also may give problems (intermodulation, clipping).

 

[BigBoss]

but all the amplifiers have its own matching network.

Post your schematic here and let's check it out.