Abstract: A multi-layer substrate comprising: a plurality of metal layers, on each of which a predetermined printed-circuit pattern is formed; and at least one insulating layer formed between the metal layers, wherein the plurality of metal layers includes: at least two high-frequency signal layers for transmitting a high-frequency signal. At least one ground layer provides a ground for the other metal layers, and wherein at least one via hole is formed through the multi-layer substrate to connect the high-frequency signal layers to each other. An impedance-matching hole passes through the ground layer so as to provide a path through which the via hole passes, and wherein a distance between the via hole and the ground layer is adapted for adjustment by the impedance-matching hole to adjust capacitance, so that a quasi waveguide is formed and impedances in part of the hole are matched when a high-frequency signal is transmitted through the hole.

Abstract: An optical receiver module is disclosed with a top open can (TO-Can) structure that includes a stem with holes thereon. The holes pass through both sides of the stem. A photo diode mounted on an upper side of the stem, for converting an optical input signal into an electric current. The optical receiver module includes a trans-impedance amplifier, mounted on the upper side of the stem, converts the electric current output from the photo diode into RF signals having opposite phases, amplifies the converted RF signals, and outputs the amplified RF signals to the outside via corresponding output terminals. Signal leads, passing through the holes formed on the stem, output the RF signals having the opposite phases amplified by the trans-impedance amplifier to the outside. Ground leads, extending from a lower part of the stem, ground the stem to the outside of the optical receiver module.

Abstract: A TO-CAN type optical module for used in an optical communication is disclosed. The optical module includes: a stem provided with optical components mounted on its upper surface and a through hole formed therethrough; a plurality of pins electrically connected to the optical components via the through hole and having a signal-carrying pin protruding from the lower surface of the stem; and a pair of ground pins spaced at both sides from a protruding portion of the signal-carrying pin. The interior of the through hole of the stem has a desired characteristic impedance by the impedance matching of a coaxial cable, and the lower surface of the stem has a desired characteristic impedance by the dimensions of the protruding portion of the signal-carrying pin and the ground pins and the interval between the protruding portion of the signal-carrying pin and the ground pins.