An on-chip temperature detection device includes: a bipolar type power transistor; a mirror transistor in which a collector current, which is proportional to a collector current of the power transistor, flows; a current detection section that detects the collector current of the mirror transistor; a voltage detection section that detects a voltage between a base and an emitter of the power transistor; and a calculation section that calculates a chip temperature of the power transistor, based upon the collector current of the mirror transistor detected by the current detection section, and upon the voltage between the base and the emitter of the power transistor detected by the voltage detection section.

In solid state relay circuit including a metal oxide field effect transistor connected for switching current to a load circuit, a latch circuit including first and second transistors connected to monitor a voltage caused by current in the load circuit and to shunt current away from the field effect transistor in response to current overload in the load circuit, the first and second transistors having temperature characteristics such that they turn on in response to different voltages at different temperatures, the improvement including a second means for turning on the latch to shunt current away from the field effect transistor in response to the voltage caused by current in the load circuit, the second apparatus including temperature compensating apparatus for matching the temperature characteristics of the first and second transistors of the latch circuit whereby the latch turns on at the same voltage in the load circuit over the typical operating range of the device.

A transistor is protected from excessive power dissipation in the event of a shorted load condition by alternately turning the transistor off for a relatively long period of time during which a capacitor is discharged through a resistor network and turning the transistor on for a relatively short period of time during which the capacitor is charged through a diode by the voltage developed across a resistor connected in circuit with the transistor.

A integrated circuit, high impedance, current source/sink for wireless communications systems comprising one or more inverted bipolar junction transistors, and a method of ensuring high output impedance at RF frequencies. Mixers, differential amplifiers and transconductance amplifiers are disclosed as is the physical structure of bipolar transistors including heterojunction transistors.

A semiconductor integrated circuit comprises a transistor which has a first electrode, a second electrode and a third electrode, said transistor conducting a current of a first power source from the second electrode to the third electrode by a power supplied to the first electrode; a driver to supply said first electrode with power for driving said transistor; a reference voltage circuit to generate a reference voltage which is variable in response to temperature of said transistor, said reference voltage being used as the reference for comparison; a comparative voltage circuit to generate a comparative voltage which is variable in response to a current flowing from said second electrode to said third electrode, said comparative voltage being compared with said reference voltage; and a controller which receives said reference voltage and said comparative voltage and which supplies a control signal to said driver, said control signal being based on a result of the comparison between the comparative voltage and the reference voltage to control the power supplied to said first electrode.