| 摘要 |
A signal amplifier connected to a photodetector that converts a received optical signal to a current signal includes: a preamplifier converting the current signal to voltage and supplying the resultant voltage signal; a main amplifier amplifying the voltage signal supplied from the preamplifier and in which at least the input stage is made up from a differential circuit; two or more follower circuits provided between the preamplifier and the main amplifier and supplied with the voltage signal; resistors of equal resistance provided for each follower circuit on the paths between the output of the preamplifier and each input of the main amplifier; and a capacitor having one end connected to one of the resistors and the other end connected to ground. A low-pass filter for detecting the average potential of the voltage signal is configured by the capacitor and the resistor that is connected to the capacitor. |
