Abstract: A semiconductor integrated circuit prevents the circuit elements thereof from being destroyed by a surge current flowing therethrough when the semiconductor integrated circuit is electrically charged and improves the electrostatic tolerance thereof.

Abstract: An integrated circuit device for frequency conversion in a CATV tuner, in which the signal output from an oscillation circuit section has an improved phase noise characteristic. The mixer circuit section, including an RF input port, an LO input port, and an IF output port, and an oscillation circuit section connected to the LO input port of the mixer circuit section, may be formed on one semiconductor substrate, or on separate substrates. The mixer circuit section uses an FET as a nonlinear element and the oscillation circuit section uses a bipolar transistor as an oscillation element. By this constitution the phase noise of the signal outputted from the oscillation circuit section can be made small.

Abstract: A fixed subscriber unit is connected to one or a plurality of wire telephones through wire and to a radio base station, which is connected to a public network, through radio to mediate communication between a telephone, which is connected to the public network, and the wire telephone. The fixed subscriber unit includes a supply state detection unit for detecting an electric power supply state from an external power supply. The fixed subscriber unit further includes a supply control unit for detecting reduction of a voltage supplied from the external power supply and a power failure on the basis of the detected result of the supply state detection unit, and setting a voltage supplied to the wire telephone to a value smaller than a rated voltage when the reduction of the voltage or the power failure is detected. The rated voltage is a voltage supplied to the wire telephone when the voltage supplied from the external power supply is normal.