| 摘要 |
PURPOSE:To reduce a capacitance between signal lines relating to the propagation of a carry signal and to propagate the carry signal at high speed, by providing two MOSFETs which open/close a carry propagation signal. CONSTITUTION:When the carry propagation signal P is at a prescribed level, the MOSFETs 12 and 13 are opened, and carry input signals CI and NCI of positive logic and negative logic inputted from respective source of the MOSFETs are outputted to output terminals 8 and 9 respectively as carry output signals CO and NCO of positive logic and negative logic. Also, when FETs 12 and 13 are cut off by the carry propagation signal P, signals generated by a carry signal deletion circuit 14 or a carry signal generation circuit 15 are outputted to the output terminals 8 and 9 as the carry output signals CO and NCO of positive logic and negative logic respectively. In such way, it is possible to reduce the capacitance on the signal line relating to carry propagation, and to propagate the carry signal at high speed.
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