This paper proposes a color mixing control system that provides adjustable color mixing using pulse-modulation
light brightness period control while driving red-green-blue (RGB) light-emitting diodes (LED). The proposed control
system includes a clock unit that provides a first clock signal and a second clock signal with a frequency lower than that
of the first clock signal. Three control units are coupled to three LEDs emitting three different colors, respectively.
Each control unit is operated based on the clock signals and a corresponding set of first and second reference values
output to a driving pulse signal to the corresponding LED. Using four bit digital signal control, 4096 different colors and
16 gray levels can be provided by the digital pulse width modulator (DPWM) system. The system works using a single
5V power supply with a maximum clock frequency of 1MHz.