Abstract: Circuit for indicating when a voltage indicative of a condition, such as the presence of smoke, changes to a value outside of a given voltage range. It includes an oscillator which oscillates in response to a value of voltage within said range and which stops oscillating when the voltage changes to a value outside of said range. A circuit coupled to said oscillator sounds an alarm when the oscillations cease.

Abstract: A ground fault detector which exhibits greater sensitivity to sensing coil current during the initial portions of a-c line voltage half-cycles than during the final portions of those half cycles. This improves its response to resistive ground faults in the presence of unbalanced capacitance to ground conditions of the a-c power lines.

Abstract: A modified connection of elements in a push-pull transistor amplifier with driver circuitry providing over-current protection, which amplifier has previously been described by the present inventor in U.S. Pat. No. 3,855,540, increases the current gain through the push-pull transistor amplifier by a factor equal to the common-emitter forward current gain (h.sub.fe) of a transistor.

Abstract: When a reduction in the current flow through one transistor of a long-tailed pair connection of transistors is sensed under conditions where rapid slewing is desired, the supply of tail current is increased to increase the rate at which the long-tailed pair can change the charge on the capacitances of following stages.

Abstract: Each half of a differential-input amplifier stage has an input terminal connected to the emitter electrode of a transistor. Resistances are provided for sensing the flow of current through the principal conduction path of each transistor. Output signal current for the stage is taken from the collector of at least one of the transistors and applied to the input of a following one of a cascade connection of amplifier stages. Voltage comparator means sense the drop in potential across one of the resistances caused by reduction of current in one half of the diffferential-input amplifier to increase the current available to the other half. This increases the output signal current available to charge or to discharge capacitance in the stage(s) cascaded after the diffferential-input amplifier, increasing the slew rate of the cascade.

Abstract: Circuitry for providing temperature-compensated regulation of the voltage between first and second terminals includes a first, shunt regulator transistor with emitter and collector connected to the first and second terminals, respectively, and a direct coupled degenerative feedback connection between the second terminal and the base of the first transistor. This feedback connection includes a second transistor of the same conductivity type as the first transistor connected in common base-amplifier configuration, with a positive-temperature-coefficient offset potential being maintained between the second terminal and the emitter of the second transistor, with a negative-temperature-coefficient being applied between the first terminal and the base of the second transistor, and with a predetermined flow of current being maintained between the second terminal and the collector of the second transistor, which collector is direct-coupled to the base of said first transistor.

Abstract: Circuit employing complementary field-effect transistors operated in the triode mode. A signal representing the multiplicand is applied to the gate electrode of one transistor and a signal representing the multiplier is applied to the drain electrode of the same transistor. The complement of the multiplier signal is applied to the drain electrode of the other transistor. A current indicative of the product is available at the common connection of the source electrodes.

Abstract: A current mirror amplifier in which the potentials appearing across the principal conduction paths of its master and slave transistors are maintained substantially the same. This is done by a differential-input, single-ended output amplifier, which is connected as a non-inverting amplifier in the direct-coupled feedback connection that conditions the master transistor to conduct applied input current via its principal conduction path.

Abstract: A cascade amplifier embodying the present invention includes a plurality of amplifier stages in direct-coupled cascade connection. During specified intervals interspersed with normal amplification equal potentials are imposed on the inverting and non-inverting terminals of the first amplifier stage. A direct-coupled feedback connection from the output port of the final amplifier stage to the input port of one of the amplifier stages succeeding the first includes a sample-and-hold circuit. This sample-and-hold circuit samples the signal level appearing at the output port of the final amplifier stage during said specified intervals and holds that level for the feedback connection during the intervening periods of normal amplification to provide continuing compensation against input offset potential error.

Abstract: A current mirror amplifier in which at least one of the mirroring transistors is a composite transistor in which the number of simple transistors parallelled to form the composite transistor can be selected in response to a digital signal to program the current gain of the current mirror amplifier in accordance with said digital signal. Current mirror amplifiers with programmable current gains are useful, for example, in the multiplication and/or division of analog information by digital multipliers, and in digital-to-analog conversion.

Abstract: A circuit for compensating for the departure from its nominal value of the gain of a current mirror amplifier (CMA). This departure is caused by the presence of base current in one current path of the CMA that is not present in the other current path. The common terminal current of the CMA is sensed and a circuit responsive to this current causes a current to flow at the CMA output terminal that is essentially equal to the aforementioned base currents thereby causing the CMA gain to more closely equal its nominal value. The compensated CMA may be advantageously used in combination with a differential amplifier to reduce the offset voltage of this amplifier.

Abstract: Two current amplifiers are connected in a regenerative feedback loop. One of them exhibits an exponential decrease in current gain in response to a linear increase in input current, in consequence of which the current level in the loop stabilizes at a predictable level.

Abstract: A NMOS transistor in the input current path of a PMOS current mirror amplifier senses any tendency to change of the voltage across a load driven by the output current of the amplifier. In response thereto, the NMOS transistor changes the input current of the amplifier to thereby vary its output current in a sense to maintain the voltage across the load constant.

Abstract: A first junction transistor, the emitter-to-base potential (V.sub.BE) of which determines the negative-temperature-coefficient component of the standard voltage, is provided with direct-coupled collector-to-base feedback for adjusting its V.sub.BE to condition the transistor to conduct, as collector current, substantially all of an applied current that is temperature-independent or varies linearly with temperature. The positive-temperature-coefficient component of the standard voltage is developed as the difference between the offset potentials of a pair of semiconductor junctions, one of which may be the base-emitter junction of the first transistor. The negative- and positive-temperature-coefficient potentials are linearly combined to provide the standard voltage.

Abstract: A differential amplifier suited for use in operational amplifiers employing both FET's and junction transistors has a superior gain-bandwidth product for given input offset specification. Source-coupled FET's accept input signals at their gate electrodes. Each FET is included in a composite transistor device together with a direct coupled, inverting, current amplifier having an input terminal to which the drain electrode of the FET is coupled and having an output terminal coupled to the source electrode of the FET.

Abstract: A positive-temperature-coefficient difference between the emitter-to-base potentials of two transistors in particular configuration is scaled up and added to one of the emitter-to-base potentials to develop a potential, a multiple of which is supplied as the reference potential.

Abstract: The maximum drive currents available to the output transistors of a Class B or AB push-pull amplifier are controlled as a function of their emitter-to-collector voltages, permitting the operation of the transistors over substantially their entire safe operating area ratings.

Abstract: A positive-temperature-coefficient potential is developed by scaling up from the potential difference appearing between the base electrodes of two transistors with interconnected emitter electrodes constrained by a positive feedback loop to operate with different densities of current flow through their respective base-emitter junctions. This positive-temperature-coefficient potential is added to a negative-temperature-coefficient potential derived from the base-emitter offset potential of one of the transistors, to provide the reference potential.

Abstract: A current mirror amplifier (CMA) and another current amplifier are connected in a degenerative current feedback loop with a point therein which point exhibits a low a-c impedance with respect to a-c ground and provides for sensing signal current applied thereto from an impedance element. The CMA has an input terminal connected to this sensing point, a common terminal connected to a-c ground and an output terminal connected to a constant current source load. The other current amplifier has input and common terminals connected to the CMA output terminal and to the sensing point, respectively, and has an output terminal from which sensed signal current is available.

Abstract: Current mirror amplifiers, which exhibit greater current attenuation (or gain) than prior art current mirror amplifiers taking up the same area on a monolithic integrated circuit die, are described in which the base-emitter junctions of the mirroring transistors are dissimilar in profile.