| 摘要 |
PURPOSE:To know exactly the signal voltage of a semiconductor integrated circuit without being restricted by a power supply voltage, by supplying a power source from the outside. CONSTITUTION:When the gate threshold voltage of a MOSFET 3 is '1'V and the resistance value of a load resistance 6 is higher enough than the equivalent resistance value of the MOSFET 3, the output voltage of a signal output terminal 2 becomes a voltage lower by '1'V than the voltage of a signal input terminal 1. Also, when the voltage of 7V is applied in advance to a power source supply terminal 4 from the outside, when the voltage of 5V is applied to the terminal 1, the voltage of about 4V is generated in the terminal 2. Also, when the voltage of 6V is applied, the voltage of 5V is generated. On the other hand, in case when the resistance value of the resistance 6 is not larger enough than the equivalent resistance value of the MOSFET 3, a voltage difference between the terminal 1 and the terminal 2 becomes larger than '1'V. In this way, a signal voltage in the semiconductor integrated circuit can be known exactly.
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