| US 7,474,290 B2 | ||
| Semiconductor device and testing method thereof | ||
| Masami Makuuchi, Yokohama (Japan); Norio Chujo, Tokyo (Japan); Kengo Imagawa, Fujisawa (Japan); Ritsuro Orihashi, Tokyo (Japan); and Yoshitomo Arai, Ohme (Japan) | ||
| Assigned to Renesas Technology Corp., Tokyo (Japan) | ||
| Filed on Nov. 05, 2004, as Appl. No. 10/981,715. | ||
| Claims priority of application No. 2003-378595 (JP), filed on Nov. 07, 2003; and application No. 2004-310341 (JP), filed on Oct. 26, 2004. | ||
| Prior Publication US 2005/0122300 A1, Jun. 09, 2005 | ||
| Int. Cl. G09G 3/36 (2006.01) | ||
| U.S. Cl. 345—87 [345/690; 345/88; 345/55] | 4 Claims |
| 1. A semiconductor device having a liquid crystal driver circuit,
wherein said liquid crystal driver circuit comprises: a gray-scale voltage generator circuit; a gray-scale voltage selector
circuit which receives gray-scale voltage generated in said gray-scale voltage generator circuit and selects gray-scale voltage
corresponding to gray scale; and a buffer which temporarily retains information regarding gray-scale voltage selected in said
gray-scale voltage selector circuit and gives said retained information to said gray-scale voltage selector circuit, and
said gray-scale voltage selector circuit further comprises:
a selector circuit that selects gray-scale voltage generated in said gray-scale voltage generator circuit based on an output
from said buffer;
an amplifier circuit which, in a gray-scale voltage test of said semiconductor device, compares the gray-scale voltage selected
in said selector circuit with reference voltage generated for testing said gray-scale voltage, amplifies differential voltage
between those voltages, and outputs the comparison result as binarized voltage from an external terminal; and
selection means which selects either said reference voltage or output of said amplifier circuit as information to be input
into said amplifier circuit.
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