| 摘要 |
PROBLEM TO BE SOLVED: To more stably operate an active element by preventing a noise produced by the active element from being reflected into the active element. SOLUTION: A power supply line consists of a closed circuit line 4 whose circumferential length is equal to a guide wavelength with respect to a desired frequency, a 1st power supply line 1 connected to the close circuit line 4 and a power supply section of the active element, a 2nd power supply line 2 that is connected to the close circuit line 4 at a position apart from a connecting point of the 1st power supply line 1 on the close circuit line 4 by about 1/4 of the guide wavelength and connected to a power supply and to ground via a capacitor connected in parallel with the power supply, and a 3rd power supply line 3 that is connected to the close circuit line 4 at the position apart from the connecting point of the 1st power supply line 1 to the close circuit line 4 by about 1/2 of the guide wavelength and connected to ground via the capacitor and a resistor connected in series. Thus, a noise produced from the active element is given to the close circuit line 4 via the 1st power supply line, all of the noise is outputted from the 3rd power supply line and terminated by the termination resistor via the capacitor connected in series with the resistor.
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