| 摘要 |
<p>PURPOSE: To reduce a leakage current resulting from a boosted voltage when a high voltage changeover circuit is not selected even when the cut-off characteristic is deteriorated by connecting 1st, 2nd, 3rd NMOS transistors(TRs) as specified so as to reduce a threshold voltage of the TRs. CONSTITUTION: A gate voltage VG applied to gates of 1st and 2nd NMOS 11, 12 is at a ground level and a gate voltage VENB applied to a gate of the 3rd NMOS 13 is at a power supply voltage level in the case of non-selection. In this case, a source voltage of the 3rd NMOS 13 is a voltage lower than the power supply voltage VCC by a threshold voltage of the NMOS 11. Thus, the cut-off characteristic of the NMOS 13 is improved and a leakage current from the boosted voltage VPP is reduced. Since the source and the gate of the 2nd NMOS 12 are at a ground level on the other hand, the same leakage current as a conventional current is produced. Since the leakage current results from the power supply voltage VCC applied to the terminal 16, the boosted voltage VPP is not reduced.</p> |
