Abstract: A reference voltage generating circuit generates a predetermined reference voltage being independent of the dispersion of manufacturing lots. The base and the collector of a transistor is connected to a first input terminal of an operational amplifier. A resistor is connected between a second input terminal and an output terminal of the operational amplifier. The output terminal outputs the reference voltage. A voltage independent of the current amplification factor of the transistor is supplied to the input terminal of the operational amplifier via the transistor. And, a current independent of the reference voltage is supplied to the second input terminal of the operational amplifier. Here, a current proportional to the current amplification factor of the transistor is supplied to the base and the collector of the transistor.

Abstract: An electric waveform generator for a brushless motor includes a triangular wave generator including a Voltage Controlled Oscillator (VCO), a shift register, an inverting circuit, an analog switch group, and a synthesizer. The shift register generates specified timing signals synchronized with the oscillating cycle of the triangular wave from the triangular wave generator. The inverting circuit inverts the triangular wave from the triangular wave generator. The analog switch group selects the triangular wave and the inverted triangular wave based on the timing signals from the shift register. The synthesizer outputs trapezoidal waves based on the operation of the analog switch.

Abstract: A current-detecting circuit detects the value of a current which flows out of an output circuit incorporated in an integrated circuit. A current-detecting resistor (17) is located at an intermediate point of the path along which the current flows out of the output circuit. The emitters of two NPN transistors (15, 16), for which a collector area ratio of N:1 is determined, are connected to the ends of the resistor (17), respectively. The bases of the NPN transistors (15, 16) are connected together, and the base and collector of one (15) of the NPN transistors are connected together. A current mirror circuit (14), which is made up of two PNP transistors (12, 13) and for which an input-to-output current ratio of M:1 determined, is connected to the collectors of the NPN transistors (15, 16). The base of an output NPN transistor (18) is connected to a node to which the collector of one (13) of the PNP transistors and the collector of one (16) of the NPN transistors are connected in common.

Abstract: A differential comparator of the hysteresis type is responsive to a high input difference voltage (V.sub.1 -V.sub.2). The comparator comprises two differential transistors; a hysteresis resistor connected between the emitters of the two transistors; current source means connected to one of the emitters of the two transistors, for determining an emitter current of the two transistors directly and via the hysteresis resistor; and an emitter current controller for controlling the emitter current of the two transistors on the basis of an output current derived from an output terminal. When a voltage difference between the two input terminals reaches a balanced hysteresis voltage value, and therefore no output current flows, the output current is sharply increased in a direction opposite to the preceding direction.

Abstract: A differential amplifier circuit includes a pair of differential input signal terminals, first and second current output terminals, a first transistor whose collector is connected to the first current output terminal, a second transistor whose collector is connected to the second current output terminal, a third transistor whose collector and base are respectively connected to the emitter of the first transistor and the emitter of the second transistor, a fourth transistor whose collector and base are respectively connected to the emitter of the second transistor and the emitter of the first transistor, first and second resistors, and a constant current source circuit connected to the emitters of the third and fourth transistors via the first and seond resistors.

Abstract: A differential current distributing circuit includes a first current path including a first resistor, collector-emitter path of a first transistor of first conductivity type and emitter-collector path of second conductivity type which are connected in series between the output terminal of a constant current source and a first current output terminal and a second current path including a second resistor, collector-emitter path of a third transistor of first conductivity type and emitter-collector path of a fourth transistor of second conductivity type which are connected in series between the output terminal of the constant current source and a second current output terminal. The base electrode of the first transistor is connected to the output terminal of the second resistor and the base electrode of the third transistor is connected to the output terminal of the first resistor.