| 摘要 |
A power supply circuit produces a supply voltage to be supplied to a microprocessor which is an integrated circuit. A transmission line type noise filter includes a signal input terminal, a signal output terminal and two ground terminals corresponding respectively to the signal input terminal and the signal output terminal. The transmission line type noise filter eliminates a high-frequency component of DC voltage applied to the signal input terminal and outputs it from the signal output terminal. A first power supply line pattern, formed on a printed-circuit board, connects an output terminal of the power supply circuit with the signal input terminal of the transmission line type noise filter. A second power supply line pattern connects the signal output terminal of the transmission line type noise filter with a power supply terminal of the microprocessor. A ground land pattern is connected with an external ground potential through via holes and makes a connection between the two ground terminals.
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