Kabushiki Kaisha Toshiba

Tokyo Shibaura Denki Kabushiki Kaisha

Kazuo Imanishi

Masaru Hashimoto

Makoto Mori

Akihiro Iida

An AC switch device of the present invention comprises an n,region formed on a p-type semiconductor substrate, first and second p-type regions separately formed in the n,region, a first source region (n,region) and a first sense region (n,region) separately formed in the first p-type region, a second source region (n,region) and a second sense region (n,region) separately formed in the second p-type region, first and second channel regions formed in upper parts of the first and second p-type regions located between the first source region (n,region) and the first sense region (n,region), on the one hand, and the second source region (n,region) and the second sense region (n,region), on the other, a first gate electrode formed above the first channel region with a gate insulating film interposed, and a second gate electrode formed above the second channel region with a gate insulating film interposed.

AC switch device used for switching AC circuit and AC switch circuit having the AC switch device

Among a plurality of power supply circuits arranged in a power supply monolithic integrated circuit, output voltages of power supply circuits except for an external microcomputer power supply circuit are monitored by a protective circuit. When an abnormal output appears at least one of the power supply circuits, the outputs of all the power supply circuits except for the microcomputer power supply circuit are cut off.

Multiple power supply system

Vertical deflection circuit

A power amplifier having a standby switch according to the present invention comprises an amplifier circuit, a bias circuit serving as a bias source of the amplifier circuit a detector circuit for detecting a variation in a power source voltage to turn on or off the standby switch, a standby circuit for extinguishing a waveform of an output voltage of the amplifier circuit the moment that the standby switch is turned off, and a delay circuit for cutting off the bias source of the amplifier circuit after a lapse of a predetermined time period after the standby switch is turned off.

Power amplifier having a standby circuit

An amplifier circuit comprises an amplifying section for amplifying an input signal voltage, and feedback resistances for supplying part of an output voltage of the amplifying section as a negative feedback signal voltage thereto. The amplifying section of the amplifier circuit includes a first voltage-current converting amplifier for converting an input signal voltage into a corresponding current, a second voltage-current converting amplifier for converting a negative feedback signal voltage into a corresponding current, an active load circuit for coupling output currents of the first and second voltage-current converting amplifier, which are set in an opposite phase relation, and for generating an output voltage corresponding to the sum of the coupled currents, a voltage amplifier for amplifying the output voltage of the active load circuit, and a control circuit for controlling the ratio of the mutual conductances of the first and second voltage-current converting amplifiers.

Gain controllable amplifier circuit

A power amplifier circuit comprises amplifier means, and mode switching means for selectively changing the amplifier means between an operational state wherein the input signal is amplified, and a stand-by state wherein the input signal is not amplified. The mode switching means includes timing means for delaying the change of the amplifier means to the stand-by state for a predetermined time after the stand-by state is selected, and means for supplying a predetermined potential to the amplifier means when the stand-by state is selected.

Power amplifier circuit with a stand-by state

A stand-by signal is supplied to a stand-by circuit for determining the operation condition is a normal operative mode or a stand-by mode to control the operation. An output signal of the stand-by circuit is delayed by a delay circuit. An output signal from the delay circuit is supplied to a bias circuit for generating a predetermined bias voltage. An audio signal supplied from the audio signal input terminal is amplified by an amplifier circuit based on the bias voltage from the bias circuit. When it is detected by an overcurrent detection circuit that an overcurrent flows in the amplifier circuit, supply of the bias voltage from the bias circuit to the amplifier circuit is interrupted by the protection circuit. The operation of the protection circuit is controlled by output signals from the delay circuit and the overcurrent detection circuit.

Audio output amplifier

A protection circuit for an output transistor which produces a protecting signal representing the power consumption of the output transistor, namely the product of collector current and collector to emitter voltage of the output transistor, thereby protecting the output transistor over a broad operating range.

Growing community of inventors

Yokohama, Japan

Kazuo Imanishi