Electronic digital logic circuitry – Interface – Current driving
Patent
1996-08-22
1998-05-05
Westin, Edward P.
Electronic digital logic circuitry
Interface
Current driving
326 81, H03K 19094, H03K 190175
Patent
active
057480117
ABSTRACT:
In the output buffer circuit, when an enable signal is inputted to deactivate the main buffer circuit (MB1) and further when a voltage higher than the first supply voltage V.sub.DD is applied to the output terminal (I/O), since the fifth P-type transistor (QP2) is turned on, the voltage at the output terminal is applied to the gate of the third P-type transistor (QP1), so that this transistor (QP1) is perfectly turned off. Therefore, it is possible to prevent unnecessary current from flowing from the output terminal (I/O) to the first supply voltage (V.sub.DD) terminal through the third P-type transistor (QP1). Further, since the sixth P-type transistor (QP4) is turned on, the voltage at the output terminal is applied to the gate of the second P-type transistor (QP6) through the sixth P-type transistor (QP4), so that this transistor (QP6) can be perfectly turned off. Therefore, it is possible to prevent unnecessary current from flowing to the first supply voltage (V.sub.DD) terminal through the first and second P-type transistors (QP5 and QP6). Further, since a voltage higher than the first supply voltage will not be applied to the gate oxide film of the second to sixth P-type transistors all formed on the same N-type substrate, it is possible to prevent the manufacturing process from being complicated.
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Nogami Kazutaka
Takahashi Makoto
Kabushiki Kaisha Toshiba
Roseen Richard
Westin Edward P.
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