| 摘要 |
PURPOSE:To provide an optical receiving device which can correct the peaking of frequency characteristic caused by a parasitic inductor and the parasitic capacity by connecting a coil, a capacitor and a resistance in parallel to each other at the post stage of a preamplifier. CONSTITUTION:A resonance circuit consists of a coil 4, a capacitor 4 and a resistance 6 at the post stage of a preamplifier 3. When an optical signal is inputted to a photodetector 1, a current flows to the photodetector 1 in response to the optical level. This current is taken out by a bias resistance 2 as an electric signal and amplified and outputted by the preamplifier 3. The impedance of the resonance circuit is maximized by the resonance frequency defined by the coil 4 and the capacitor 5, and the level of the resonance frequency is decided by the resistance 6. The amplitude of the output signal received from a terminal 10 is reduced at a level close to the resonance frequency owing to increase of the impedance of the resonance circuit. Thus it is possible to correct the parasitic capacity of the photodetector 1 and the peaking of an inductor and to flatten the frequency characteristic by giving the characteristic adverse to the peaking of the photodetector 1 to the resonance circuit. |
