| 摘要 |
PURPOSE:To obtain large SN ratio without any decrease in a load impeadance of an optical receiver element at high frequency band by a method wherein a band- pass filter is built with positive utilization of static capacity which is accompanied by optical reciever element and an input of an amplifier. CONSTITUTION:By a band-pass filter being built between an optical receiver element 1 which has a stray capacity 4 and an amplifier 3 which has an input capacity 5 operational frequency band is widened. That is to say the element 1 is grounded through a resistor 2, and an inductance 7, and a variable capacitor 10 is put between the element 1 and the amplifier 3 in series. And beteen an inductance 7 and the connecting point of the element 1 and resistor 2, an inductance 6 and a variable capacitor 9 which are grounded respectively are added, and between the capacitor 10 and the amplifier 3 an inductance 8, a variable capacitor 11 and a resistor 12 which has the same resistance value as the resistor 2 are also added, and another terminals of them are grounded respectively. By this method there is no decrease in the load impeadance of device 1, and no attenuation takes place in signal voltage. |
