| 摘要 |
PROBLEM TO BE SOLVED: To observe the power supply voltage value and its fluctuating value in a semiconductor integrated circuit in a noncontact state. SOLUTION: On a voltage value on a power supply wire 1 in the semiconductor integrated circuit 10, the period of a constant frequency carrier wave signal is modulated by using an FM modulating circuit 3 built in the semiconductor integrated circuit 10. This constant frequency carrier wave signal is outputted as a radio wave from a transmitting side antenna 4 arranged in the semiconductor integrated circuit 10. The radio wave is received by a receiving side antenna 5 to be converted into a voltage value by an FM demodulating circuit 6. The converted voltage value is observed by an oscilloscope 7 connected to the FM demodulating circuit 6. The transmitting side antenna and the receiving side antenna 5 can be realized, for example, by wiring (1 to 2 cm) on a printed board.
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