Patent ID: 7411179

Claim:
A photodetector module that is equipped with a photodetector and is connected to a substrate that is a target of transmission of an electric signal which is photoelectrically converted in the photodetector, the photodetector module comprising: an amplifier which amplifies the electric signal from the photodetector; a board on which the photodetector and the amplifier are mounted; a dielectric placed between the board and the substrate; and a lead pin extending through the board and the dielectric to the substrate, so as to transfer the electric signal amplified by the amplifier to the substrate; wherein output of the amplifier includes a capacitance component, and an output impedance of the amplifier is higher than an impedance that matches with the substrate; and thickness of the dielectric in a direction from the board to the substrate is such that an inductance component of the lead pin includes an inductance component canceling the capacitance component of the amplifier, and impedance matching with the substrate can be achieved.