Abstract: An optical subscriber transmission system is formed of an office center unit and a plurality of subscriber units connected to the office center unit in parallel via an optical fiber, in which system a downward signal is transmitted from the office center unit to the plurality of subscriber units via the optical fiber and upward signals are transmitted from the plurality of subscriber units to the office center unit. The optical subscriber transmission system includes a signal level detecting unit for detecting a level of the downward signal from the office center unit which is received by a subscriber unit, and a control circuit for controlling, based on a detected signal level obtained by the signal level detecting unit, an upward signal to be transmitted from the subscriber unit to the office center unit so that a level of the upward signal is decreased in accordance with an increasing of the detected signal level.

Abstract: In an equalizing amplifier that equalizes an electric signal obtained from a light signal received via an optical transmission path, an AGC circuit generates first and second signals from the electric signal by referring to a threshold voltage. The first and second signals are complementary signals. An offset compensation circuit generates a first difference signal based on a difference between the first and second signals, compares the first difference signal with a first reference signal, and outputs, as the threshold voltage, a resultant error signal to the AGC circuit. The threshold voltage is varied so that it is located in the center of an amplitude of the electric signal whereby an offset of the AGC circuit can be compensated for.

Abstract: A high speed electronic circuit has a cascode circuit configuration and is provided with a bias current source (CS.sub.0) between an emitter and a base of a load transistor (Q) in the cascode circuit configuration for compensating a base-emitter voltage (V.sub.BE) of the transistor to eliminate an adverse effect of charging and discharging at a stray capacitor (C) which can be connected between the base and the emitter of the transistor. The high speed electronic circuit can be applied to an; circuit, a level shift circuit, a level shift discrimination circuit, a signal distribution circuit, a signal synthesization circuit and a frequency band control circuit.

Abstract: An integrated circuit device including: at least one semiconductor chip (3) having a plurality of circuit elements; a package (21 to 24) enclosing the semiconductor chip with a hermetic seal; and a strip line unit (15-2, 11-1b, 11-2, 20 and 23:15-1, 11-1, 11-2, 11-3, 12-1 and 20) for connecting the circuit elements in the semiconductor chip to circuit outside of the package. The stripline unit having a microstrip line structure and a triplate strip line structure serial-connected to the microstrip line structure and connecting the outside circuits. The triplate strip line structure has a characteristic impedance equal to that of the microstrip line structure so that the strip line unit satisfies the required impedance matching.

Abstract: An integrated circuit device including a stacked layer unit having a plurality of stacked layers each having an insulation layer and at least one conductive layer strip formed on a surface of the insulation layer, and at least one chip mounted on the top of the insulation layer and having a plurality of circuit elements. The IC device also includes at least one first conductive member formed in the stacked layer unit, having a low inductance for first signals applied thereto and operatively connecting the first signals to be transferred between the circuit elements. The IC device further includes at least one second conductive member formed in the stacked layer unit, having a higher inductance for the first signals than that of the first conductive member and operatively connecting second signals to be transferred between the circuit elements the stacked layer unit, the chip, and the first and second conductive members are enclosed by a package and sealed with a hermetic seal.

Abstract: A semiconductor device provided with signal lines which connect a chip, provided at a top portion of a package, with external terminals provided at a bottom portion of the package. The signal lines have portions formed along side surfaces of the package. Ground surfaces are formed at predetermined distances on two sides of the high-speed signal lines. A coplanar waveguide is formed by the high-speed signal lines and the ground surfaces, so the impedance of vertical portions of the high-speed signal lines is matched to the circuits connected thereto.