the spares of commonly used drivers are hard to find, such as 2sc5570 etc and are very costly too; if get some they may fake ones . i am trying to make a driver using igbts (FGA 25N 120 available cheaply). i wish to use the half bridge topology.
the problem is that usually sine wave is used to drive the transducers,is it a good practice to drive them with square wave? the frequency is 20 khz.what are the drawbacks if square wave is used instead of sine wave?

 

The problem with driving an IGBT with a squarewave is that you must continually charge and discharge the substantial gate capacitance (~3700 pf). As with a MOSFET you need to drive the gate with a current source/sink in order to avoid excessive power dissipation.

 

The transducer data sheet should tell you the limits and characteristics of electrifying it.