Abstract: Pulse width modulation systems and methods are described. In one aspect, a pulse width modulation system includes a register and a code word generator. The code word generator has an input for receiving a specified output frequency and a specified duty cycle and is operable to generate code words of different lengths. The code word generator is operable to generate a base code word having a length set to achieve the specified output frequency and having a thermometer code value set in accordance with the specified duty cycle. The code word generator is further operable to load the register with a code word pattern including a sequence of one or more copies of the base code word.