Hitachi-Kokusai Electric Inc.

Shoji Fujimoto

Masaki Suto

Takashi Uchida

Hidefumi Ito

Junetsu Urata

Disclosed is an amplifier apparatus that corrects mismatching of the filter transmission characteristic due to a change in the temperature of the amplifier apparatus itself and thereby stably amplifies the high-frequency signal. The amplifier apparatus converts a signal to be processed into one having an intermediate frequency band to thereby execute amplification processing. It comprises a local oscillator the oscillation frequency of that can be altered, a first frequency converter that converts the signal by the use of the oscillation frequency from the local oscillator into an intermediate frequency, a first band pass filter that band-limits the signal having the intermediate, an amplifier that amplifies the signal of the intermediate frequency that has passed therethrough, a second band pass filter that band-limits the signal of the intermediate frequency that has been output therefrom, a second frequency converter that converts the signal of the intermediate frequency that has passed therethrough into the original frequency by the use of the local-oscillation frequency, a temperature sensor that detects the temperature of each of the first and second filters , and a controller that alters the oscillation frequency of the local oscillator in correspondence with the detected temperature and thereby stabilizes the transmission characteristic of each of the first and second filters irrespective of the change in the temperature.

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Tokyo, Japan

Shoji Fujimoto