| 摘要 |
PURPOSE:To attain a high speed operation while performing countermeasure against noise at probing. CONSTITUTION:A signal received at probing is inputted from an input terminal 11 and waveform-shaped in a buffer circuit 1 and noise superimposed on the signal is eliminated by a hysteresis characteristic of the buffer circuit 3 having a feedback resistor 4. On the other hand, an input signal such as a clock signal received in the usual operation of a semiconductor integrated circuit is received from an input terminal 12 and waveform-shaped by a buffer circuit 3. The level of the input terminals 11, 12 is kept to a low level by pull-down resistors 13, 14 respectively when the signal is not received. Then either of the signals is alternatively outputted from a NOR circuit 5 and the signal from which noise is eliminated is outputted to an output terminal 15 via an inverter 6 at probing and the signal from which noise is not eliminated is outputted usually. |
