Hi,

I don't know if this is what you mean but there are amplifiers used in sensing and detection applications which are based on radar principles. Here, you may be trying to "sound" a material to observe its structural properties.

In order to partially compensate for the variations in attenuation levels experienced by signals reflected from near and far targets, the gain of the amplifier is usually increased with time, starting from an initial value (when near target echos arrive) to a larger final value (when far target echos arrive at the receiver).

However, I don't know if the term "dynamic gain" is used here. If you are more interested, just read some apps on ultrasound applications.

Regards,

Vivek