How to get an output of 100V from a 3.3 V pulse waveform?
The TI DRV2700 is a a part that is specifically designed to generate high voltage pulses for driving piezos. It has a built in boost converter for generating the 105V high voltage output from a 3-5v input. 

You can read more about it here...

http://www.ti.com/product/DRV2700