A liquid crystal display (LCD) device having an LCD panel with a plurality of pixels is disclosed. The LCD device includes gate and data driving circuits to provide a gate pulse and a data voltage to the pixels, respectively, and a timing controller to control the gate and data driving circuits. The LCD device also includes a backlight unit to provide light to the liquid crystal panel. The backlight unit includes a light source having at least one LED channel, a driving voltage generator to supply a driving voltage to the LED channel, and an LED driver to supply a conditional pulse width and amplitude modulation (CPWAM) signal to the LED channel. The CPWAM signal has a pulse with an amplitude and a width that are both variable from one period of a predetermined length to another period of the predetermined length.