Help for a 5V to 15V level shifter
It sounds like you want some sort of interface glue between a 
FPGA DE2 board cyclone II from altera (generating PWM generation)
and a ARCAL 2108 driver.

The 2108 requires a 15 VDC power supply connected to its VDD and GND pins.
I'm guessing your FPGA is getting power from a 9V DC power adapter plugged into a mains outlet, right?
You need a similar 15 VDC power adapter plugged into the same power source -- mains power -- to power the 2108.

The 2108 also has a "logic input voltage" Vim, and two data inputs InA and InB.
The datasheet claims that those inputs support "CMOS or HCMOS input level ... All logic inputs are Schmitt trigger type.".
So I'm guessing the 2108 board runs InA and InB into something like a CD4093, which runs fine from a "logic input voltage" of 5V or 15 V. (Could you look at the board and tell us the part number of the IC on the 2108 board connected to those inputs?)

The datasheet says that with Vim connected to 5 V,
the input thresholds are 2.6 V and 1.3 V.
It appears that you can directly connect the pins from the DE2 board -- "VCC5" pin (+5 VDC) and 2 digital output pins that PWM from 0 V to 3.3 V -- to the 2108 board -- with Vim set to +5 VDC -- without any interface glue.

(If you did need to do logic-level translation, Step up 3.3V to 5V for digital I/O and "3V Tips ‘n Tricks" have some ideas).