Liquid crystal display driver including a voltage selection circuit having optimally sized transistors, and a liquid crystal display apparatus using the liquid crystal display driver

摘要

A liquid crystal display driver includes a first selecting circuit configured to select a voltage from a first voltage range based on a digital signal; and a second selecting circuit configured to select a voltage from a second voltage range based on the digital signal. A voltage which is applied between a diffusion layer and a back gate of a first MOS transistor contained in the first selecting circuit is smaller than a voltage which is applied between a diffusion layer and a back gate of a second MOS transistor contained in the second selecting circuit. Also, an offset length of the first MOS transistor is shorter than that of the second MOS transistor. The liquid crystal display driver may further include a voltage generating circuit configured to supply gradation voltages of the first voltage range and the second voltage range to the first and second selecting circuits. One of the first and second selecting circuits outputs one of the gradation voltages based on the digital signal.