| 摘要 |
A half adder includes a first drive stage having an input and connected at its output a carry output and a second drive stage having an input and connected at its output to an addition data output. Further, a circuit is provided to precharge the inputs and the outputs of the first and second drive stages at a first timing so as to put these drive stages in a first logic condition, and then to put these drive stages in an operable condition at a second timing later than the first timing. A first logic stage is connected to a data input and a carry input, respectively, so as to generate a first logical signal to the inputs of the first and second drive stages, when the data input and the carry input assume a first logic level, thereby to put the drive stages in a second logic condition opposite to the first logic condition. Futhermore, a second logic stage is connected to the output of the second drive stage and having inputs connected to the data input and the carry input, respectively. This second logic stage is adapted to forcedly change the logic level of the second drive stage output when the data input and the carry input assume a second logic level opposite to the second logic level and at a third timing later than the second timing.
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