Gradation voltage selecting circuit, driver circuit, liquid crystal drive circuit, and liquid crystal display device

摘要

A gradation voltage selecting circuit inlcudes a plurality of gradation selecting MOS Tr groups, M-pieces half gradation voltage MOS Tr groups, a switching portion and a control portion. Each of the plurality of gradation selecting MOS Tr groups corresponds to one gradation voltage. The M-pieces half gradation voltage MOS Tr groups are connected to each other in series. The control portion supplies a second signal in response to a second display data. The first gradation selecting MOS Tr group selects a first gradation voltage in response to the second signals. The second gradation selecting MOS Tr group selects a second gradation voltage in response to the second signals. The first and second gradation selecting MOS Tr groups and the M-pieces half gradation voltage MOS Tr groups voltage-divide a gradation voltage between the first gradation voltage and the second gradation voltage into (M+2) equal parts in response to the second signal, and generate (M+1)-pieces half gradation voltages. The switching portion selects and outputs one of the (M+1)-pieces half gradation voltages into the display portion in response to the second signal. The (M+1)-pieces half gradation voltages are determined by ON resistance of the first and second gradation selecting MOS Tr groups and the half gradation voltage MOS Tr group.