| 摘要 |
A thin-film transistor circuit (10) has a main thin-film transistor (Trl) and an input gate protection device (11) formed by first and second subsidiary thin-film transistors (Tr2) and (Tr3) connected in series and to the gate electrode (1) of the main thin-film transistor (Tr1). The gates (4 and 7) and one of the main electrodes (5 and 9) of each of the first and second subsidiary thin-film transistors (Tr2 and Tr3) are connected. The other main electrodes (6 and 8) of the first and second subsidiary thin-film transistors (Tr2 and Tr3) are connected together so that only one of the first and second subsidiary thin-film transistors (Tr3 and Tr3) conducts when a voltage above a threshold voltage is applied to the gate electrode (1) of the main thin-film transistor (Tr1). The first and second subsidiary thin-film transistors (Tr2 and Tr3) have channel regions (20) of a length (L) selected for causing breakdown of the other one of the first and second subsidiary thin-film transistors (Tr2 and Tr3) when a given voltage greater than the threshold voltage is applied to the gate electrode (1) of the main thin-film transistor (Tr1), thereby rendering both the first and second subsidiary thin-film transistors (Tr2 and Tr3) conducting.
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