| 摘要 |
PURPOSE:To keep the reception sensitivity high in a certain frequency range with a modulation frequency as the center by providing an amplifier with the notch filter characteristic for frequencies in the vicinity of the signal modulation frequency. CONSTITUTION:A photodetector 1 receives modulated light like infrared rays and photoelectrically converts it by reverse bias. An amplifier 2 which amplifies the output of the photodetector 1 has a certain amplification factor with the fundamental frequency of modulation of infrared rays or the like as the center and has the notch filter characteristic in the vicinity of the fundamental frequency. Thus, the reception sensitivity is kept high in a certain range with the modulation frequency as the center, and the gain of a specific frequency can be considerably reduced before reception of noise from the external, and the output of a light reception module has a high ratio of signal components and is easily handled. |
