| 摘要 |
PROBLEM TO BE SOLVED: To provide an input protection circuit which protects an internal circuit even when serge voltage of negative polarity is applied to an input terminal. SOLUTION: Respective circuit elements constituting the input protection circuit 21 are formed in an area formed on a SOI substrate by trench isolation to insulate the forming areas of the respective elements reliably. Then, when the serge voltage of negative polarity is applied to the input terminal 1, a zener diode 14 constituting a clamping circuits 42N is conducted to turn on a field effect transistor 13 to form a current path from a circuit ground to the input terminal 1 to protect the internal circuit 3. COPYRIGHT: (C)2007,JPO&INPIT
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