| 摘要 |
PURPOSE:To easily perform an operation test by constituting the testing circuit of a carry look-ahead circuit by a dynamic inverter whose input is the output signal of a logical gate. CONSTITUTION:By inputting the output of a NAND gate 14 to the dynamic inverter 11, the output of the inverter 11 is changed from high to low. In this case, when a signal 7 is not activated, the signal 7 is at a low level at all times so that pulses are not generated to the output 14. Thus, the output 12 remains at a high level at all times. When only an arithmetic result is considered, since carry transmitted through the internal part of an arithmetic device is outputted for carry output 10, a normal result can be obtained. However, since the carry is not looked ahead, a highest operational frequency is lowered. Also, when carry look-ahead conditions are active at all times and a fault occurs, since the correct carry output 10 is not obtained, the fault is easily discriminated. |
