The presence of the amplifier is crucial since with my 12Ω load the output peak current may be near to 2A.
My main problem with this configuration is that my square wave generator is (and must be, for my project) adjustable. So, I can choose its amplitude value and set it from 0 to 20V, while the voltage supply is 24V.
Since the voltage supply is 24V, there will be a huge voltage drop between collector and emitter terminals, which will become heat.
Do you have an alternative configuration which avoids this problem?
It's exactly the same problem of a general linear voltage regulator. In such a case it's solved by choosing a PWM switched mode regulator. But that's true for a DC voltage regulator. Is there a similar configuration for a square wave voltage regulator?