Sgsates Componenti Elettronici S.p.a.

Sgs Microelettronica Spa

Sgs Ates Componenti Elettronicie S.p.a.

Sgs Componenti Elettronici S.p.a.

Sergio Palara

Aldo Torazzina

Bruno Murari

Silvano Tintori

A short circuit protection device for a unitary voltage gain signal transducer circuit (G.sub.v) and for a load impedance (R.sub.L) coupled to the transducer circuit includes a first (A.sub.1) and a second (A.sub.2) threshold comparator circuit and an actuator circuit (ACT). The input terminals of the first comparator (A.sub.1) are coupled to the transducer circuit input and output terminals and the output terminal of the first comparator is coupled to an activation terminal of the actuator circuit. The input terminals of the second comparator (A.sub.2) are coupled to the ends of the load impedance and the output terminal is coupled to an inhibit terminal of the actuator circuit. A first output terminal of the actuator circuit is coupled to an inhibit terminal of the transducer circuit, while a second output terminal of the transducer circuit is used to deliver a small current I.sub.1 to the load impedance.

Short circuit protection device for an integrated circuit and a load

A device for protecting a push-pull output stage (G.sub.v) against a short-circuit between the output terminal (A) and the positive pole (+V.sub.cc) of the supply, comprising a first (A.sub.1) and a second (A.sub.2) threshold comparator, both having a first input terminal coupled to the output terminal (A) of the output stage and both having a second input terminal coupled to a predetermined voltage reference. The reference potential (RIF.sub.1) to which the threshold comparator (A.sub.1) is coupled is kept at a potential which is lower than the other reference potential (RIF.sub.2) to which threshold comparator (A.sub.2) is coupled. The output terminal of the first comparator (A.sub.2) is coupled to the activation terminal of a low impedance circuit means (LI) inserted between the output terminal (A) of the output stage and the negative pole (-V.sub.cc) of the supply. The output terminal of the second comparator (A.sub.2) is coupled to an inhibitor terminal of the output power amplifier stage (G.sub.v).

Device for protecting a push-pull output stage against a short-circuit

A capacitor which is progressively chargeable in response to a switching on of the equipment, however brought about, is associated with an oscillating circuit with intervention threshold. As the load voltage of said capacitor increases the oscillating circuit shifts from a first to a second operating state, generating a switch-on current for the audio amplifier. The latter can be placed in stand-by condition by discharging to earth said capacitor by means of a suitable switch.

Audio amplifier switch-on control circuit

A protective device for a power element of an integrated circuit includes a circuit element for detecting and processing the value of the current flowing through the power element and the voltage supplied to the power element. The circuit element generates a measuring signal which, when it reaches a predetermined limit value, activates a threshold circuit which reduces the current level in the power element. The protective device also includes a circuit element for amplifying the measuring signal when it reaches the predetermined limit value.

Protective device for a power element of an integrated circuit

The output stage for power amplifiers, in particular of the minimum drop, low tension type, is intended for use with apparatus which do not require a high output current, which output stage can operate at a lower minimum voltage supply than comparable known stages. The output stage comprises upper and lower sections interposed between a power supply line and a ground line, each section including transistors across which voltage drops (V.sub.CE sat, V.sub.BE) appear and forming current sources for each section, diodes, and at least one current mirror circuit of the multiplying type adapted to determine as a first approximation the current gain of each section. The minimum voltage drop between the power supply line and ground line, as computed for any electric line connecting the power supply line and ground line, never exceeds the value of V.sub.BE +2V.sub.CE sat.

Output stage for power amplifiers

A monolithically integratable constant-current generating circuit includes a current-generating circuit having a control terminal and two output terminals, from which currents flow that are bound by a constant proportionality ratio. There is connected to one output terminal the input branch of a circuit having a current mirror and having a current gain which varies with the level of the current itself. A first input terminal of a current-comparator and amplifier circuit is connected to the output branch of the current mirror; a second input terminal is connected to the second output terminal of the current-generating circuit and the control terminal is connected to the output terminal of the current-comparator and amplifier circuit.

Monolithically integratable constant-current generating circuit with low

A current control circuit coupled to the final stage of the amplifier automatically adjusts the bias current of the final stage so that it is low in the no-load state and higher in the load state. The low no-load value avoids useless energy leakages and heat dissipations, while the higher load value avoids 'cross-over' distortions.

Power audio-amplifier with automatic adjustment of the bias current

A protection device for a power output circuit, designed such that the device protects the power output circuit from damage due to output overloads and simultaneously eliminates the power dissipation of the protected device, thereby conserving power and eliminating unnecessary heating of both the protected device and adjacent components. The protection device includes a comparator for comparing the voltage at the input to the power output circuit with the voltage at the output of the power output circuit. If the power output circuit has a unity voltage gain, its voltage output equals its voltage input under normal operating conditions but its voltage output becomes lower than its voltage input under overload conditions. The comparator is arranged to inhibit the power operation of the power output circuit and reduce its power dissipation to zero when the input voltage of the power output circuit exceeds the output voltage thereof by a specified value, that is, under overload conditions.

Overload protection device for power output circuits

An a-c linear amplifier with two push-pull-connected output transistors includes an ancillary transistor which, during saturation of one of the output transistors and the simultaneous cutoff of a controlled transistor driving these output transistors through a set of pilot transistors, conducts to maintain the base potential of this controlled transistor at its conduction threshold for preventing a distortion of the end of the flattened peak of the corresponding half-cycle of the output voltage. The ancillary transistor has one of its input leads maintained at a fixed biasing potential and the other of its input leads connected to a point of output-dependent variable voltage that allows its conduction during the flattened peak only.

Linear amplifier with distortion correction

A linear alternating-current amplifier with push-pull-connected first and second output transistors Q.sub.1, Q.sub.2 includes a pilot transistor Q.sub.4 and a control transistor Q.sub.3 which drives the first output transistor Q.sub.1 into saturation when the resistance of the pilot transistor Q.sub.4 is high. The control transistor Q.sub.3 has its base connected to the collector of the pilot transistor Q.sub.4 and its emitter connected to the junction of the emitter of the first output transistor Q.sub.1 with the collector of the second output transistor Q.sub.2, the latter connection including a biasing resistor R in series with a constant-current generator G (or an equivalent resistor R.sub.G or fixedly biased transistor Q.sub.G) which maintains the potential difference between the base and the emitter of the control transistor Q.sub.3 at its conduction threshold during saturation of the pilot transistor Q.sub.4 and the second output transistor Q.sub.2.

Linear alternating-current amplifier

An integrated power amplifier, composed of a multiplicity of elemental transistors epitaxially grown on a semiconductor chip, has base, emitter and collector terminals each connected in parallel to corresponding electrodes of the several elemental transistors. Each elemental transistor comprises two active emitter zones on opposite sides of a central contact zone conductively linked therewith by restricted connecting zones within the substrate, the contact zones of these transistors carrying emitter electrodes which are connected by a metallic strip to the emitter terminal. The array of transistors is divided into several parallel rows in each of which the width of the connecting zones progressively decreases from a transistor electrically closest to the base terminal to a transistor electrically closest to the emitter terminal, resulting in a progressive increase of the individual emitter resistances of these transistors to an extent compensating the voltage drop along the metallic strip between successive emitter electrodes.

Growing community of inventors

Bareggio, Italy

Sergio Palara