Pulse width modulation is used in power converters to modulate a reference signal into gating pulses for IGBT switches. This conversion can be carried out using analog circuits or digital circuits, such as DSPs and microcontrollers. A more efficient and faster solution is the use of field programmable gate arrays (FPGA). This paper demonstrates how to build a variable pulse-width modulation (PWM) waveform based on Xilinx FPGAs. It involves the design, VHDL coding, functional and timing simulation and synthesis using Spartan/sup TM/-II FPGAs. Simulation results have proven the design principles and theoretical analysis.