| 摘要 |
PROBLEM TO BE SOLVED: To provide a limiter circuit that prevents damage to a low noise amplifier connected, and widens a range of normal operation by limiting a range of saturation of the amplifier.SOLUTION: The limiter circuit exemplarily includes: a PIN diode connected between a ground and an input terminal of a low noise amplifier connected to a high frequency input terminal and having a constant saturation input power range; a transmission line a quarter wavelength long at a predetermined frequency having one end connected to the input terminal of the low noise amplifier and the other end grounded; and means for, when a signal within the saturation input power range is input to the input terminal of the low noise amplifier, connecting a series connection of a power setting resistor and a constant voltage power supply between the other end of the transmission line and the ground to lower the signal input to the input terminal of the low noise amplifier to a signal within a normal input power range at a lower power level than the former range before input to the input terminal of the low noise amplifier. |
