Bell Telephone Laboratories

Lucent Technologies Inc.

At&t Bell Laboratories

Sony Corporation

At+t Corp.

American Telephone & Telegraph Co., At&t Bell Laboratories

Sony Pictures Entertainment, Inc.

Milton L Embree

David C Goldthorp

Robert Frederick Lee

Earl O Martin

John Francis O'Neill

Dieter J Knollman

David R Vogelpohl

William G Garrett

Donald Raymond Laturell

Jonathan Herman Fischer

Muhammed Ayman Shibib

Paul M Embree

Paul C Davis

Brian K Horton

Rouben Toumani

Tom D Arntsen

Joseph H Havens

Steve W Bell

Elizabeth E Perry

Embodiments of the present invention are directed to interface devices that provide an interface between a first device and a second device, where the interface device provides electrical isolation between the first device and the second device, and where codec processing is distributed between the first-device side and the second-device side of the interface device. In a preferred embodiment, the second device has a transmission line, the interface device is a modem, and the electrical isolation is provided by one or more digital couplers that transmit sigma-delta signals that are coded and decoded in both the first-device-side and second-device-side circuitries of the modem.

Interface devices providing electrical isolation

A semiconductor structure having a temperature sensor placed in close proximity to gate and source and/or drain electrodes. The sensor is compatible with conventional semiconductor processing and is typically made from doped polysilicon having a large temperature coefficient of resistivity. At least one sensor may be placed under, but insulated from, source or drain electrodes to protect against high electric fields. The sensor is also compatible with bipolar semiconductor structures.

Semiconductor structure for thermal shutdown protection

A power-conserving, linear and broad band RF amplifier, suitable for use at more than one band in the ultra-high frequency regions allotted to radiotelephone transceivers, employs an emitter-follower output transistor to deliver the nominal 1.0 milliwatt RF power to a single-ended load from a low voltage battery, typically 2.7 v. dc, without the use of output coupling transformers. The amplifier receives only a small differential input signal from the preceding mixer or multiplier stage having a typical peak-to-peak magnitude of 0.3 v. The differential input signal is applied to the emitters of a pair of transistors whose bases are interconnected, one transistor of which (B6) is diode-connected in a current-mirror configuration and the other (B5) of which is configured in a common-base connection with emitter degeneration. The signals are summed at the collector of the common-base transistor to deliver a substantial voltage swing, illustratively 1.7 volts peak to peak, which is large enough to drive the base of the emitter-follower output transistor (B3) without requiring the high standby current in the emitter-follower normally required to maintain an emitterfollower in Class A operation.

Low-voltage radio frequency amplifier

Embodiments of the invention include an amplifier having an enhanced feedforward arrangement. In a typical operational amplifier output stage of this type, conventional feedforward arrangements comprise one or more active electrical components coupled between the second stage amplifying transistor and the negative output driver. The enhanced feedforward arrangement includes a resistor connected between the second stage amplifying transistor and the negative voltage source and a second resistor connected between the second stage amplifying transistor and the negative output driver. Alternatively, a capacitor is connected in parallel with the second resistor. In this manner, feedforward arrangements according to embodiments of the invention advantageously provide stable, enhanced frequency response, including high frequency response, e.g., above approximately 10 kHz, using economically advantageous passive rather than active electrical components. Furthermore, feedforward arrangements according to embodiments of the invention typically require less components than conventional feedforward arrangements, making them further advantageous from an economic standpoint.

Amplifier feedforward arrangement and method for enhanced frequency

The specification relates to a thermal shutdown circuit for an integrated circuit. Two matching thermal sensing resistors are used to develop a voltage representing the relative differential temperature between the two resistors. One resistor is fabricated within the integrated circuit dissipating device dielectric isolation tub and therefore its temperature closely follows the temperature of the dissipating device. The second thermal sensing resistor reflects the ambient temperature of the integrated circuit. A third thermal sensing device is used to obtain actual absolute temperature at the location of the second thermal sensing resistor. By algebraically adding a voltage representing actual absolute temperature at an ambient temperature location with a voltage representing the relative differential temperature between thermal sensing resistors, a voltage representing the actual absolute temperature of the dissipating device is produced. The resulting voltage is compared to a reference voltage, the reference voltage representing a high temperature setpoint, so that when the temperature of the dissipating device exceeds the high temperature setpoint, a thermal shutdown signal is actuated.

Integrated circuit thermal shutdown system utilizing a thermal sensor

A device for providing a balanced input over a photoelectric cell used in a motion picture film projector and for providing an unbalanced output audio signal for driving subsequent elements in an audio reproduction unit connected to the motion picture film projector, wherein the reproduced output audio signal has an improved quality over that of a previously known transformer output signal. The circuit supplies an unbalanced voltage signal in response to a current generated by a photoelectric cell having at least a first and second terminal. The circuit includes: a current to voltage converter for receiving the current from the first terminal of the photoelectric cell and providing a first output voltage and a current return unit connected to the current to voltage converter for receiving the first output voltage and for providing a second output voltage and for providing a return current along the second terminal of the photoelectric cell. The circuit may also include a balanced to unbalanced voltage converter for receiving the first and second output voltages and for providing a third output voltage which is free of common mode signals, wherein the first and second output voltages comprise a balanced signal and the third output voltage comprises an unbalanced signal.

Signal converter for reproducing audio signals recorded on a film medium

The invention is an amplifier such as an operational amplifier having an output stage with a reduced quiescent current control transistor device area that provides sufficient quiescent current control for proper operation thereof. The output stage includes a current diverter or diverting arrangement whereby current flowing to the quiescent current control transistor area is reduced by diversion without jeopardizing the proper operation of the operational amplifier. In this manner, the relative size of the quiescent current control transistors can be significantly reduced without sacrificing any of the overall performance of the amplifier.

Quiescent current control for the output stage of an amplifier

The invention is an operational amplifier having an output stage for enhancing the output driver capability near the negative source voltage. The output stage of the invention includes a voltage detector in combination with a current redirector or redirecting arrangement. The voltage detector converts the voltage difference between the amplifier output and the input to the output stage of the amplifier to a control current, which is redirected at the positive source voltage and applied to the negative output driver. The current redirector, which is operably connected to the voltage detector, allows the amplifier output to be driven at full rated current (e.g., approximately 40 mA) close to the negative source voltage (e.g., within approximately 1.5 volts) while maintaining an output configuration appropriate for stability.

Amplifier output stage having enhanced drive capability

A high voltage operational amplifier includes a first differential stage whose output is supplied to a current mirror amplifier (CMA) comprised of bipolar transistors, for driving a high voltage MOS output transistor. The bipolar CMA is selected and configured to provide low equivalent input noise and low input voltage offset.

Input stages for high voltage operational amplifier

A high voltage capacitor structure for integrated circuits or the like. The capacitor includes a provision for equalizing charge when multiple capacitors are series coupled. Charge is equalized by a SiN layer overlaying, and in contact with one terminal of, the capacitor. A ground ring surrounds the capacitor structure and is also overlayed by, and in contact with, the SiN layer.

Monolithic high-voltage capacitor

A peak catcher circuit comprises an input differential amplifying circuit consisting of a pair of transistors. An input signal in the form of an electrical wave or pulse is applied between the base of the first transistor of the pair and a point of fixed potential, while a capacitor is connected between the base of the second transistor of the pair and the fixed potential. A first fixed current source is connected between the coupled emitters of the differential pair and the fixed potential, and a second smaller fixed current source is connected between the collector of the second transistor and a second fixed potential. A second pair of oppositely poled emitter-coupled, common base connected transistors is connected between the base of the second transistor of the differential pair and the second fixed potential, and there is a connection from the coupled emitters of the second pair to the collector of the second transistor of the differential pair. One transistor of the second pair having its collector connected to one side of the capacitor acts as a switch to provide charging current to the capacitor when the input voltage at the base of the first transistor of the differential pair is higher than the voltage across the capacitor, which is the same as the voltage at the base of the second transistor of the differential pair. The other transistor of the second pair acts as a voltage limiter for the collector voltage of the second transistor of the differential pair. It prevents saturation of that transistor and also reduces the voltage swing at the collector of the same transistor. This greatly improves circuit speed and prevents large errors which would occur for input voltage peaks of short duration.

Peak catcher circuit

An origination scan circuit for detecting circuit closure state in a loop circuit has a much lower impedance than does the typical loop circuit. Its source impedance is split into separate resistive parts for connecting opposite terminals of an office battery to the tip and ring leads of the loop. Currents in the separate resistive parts are sensed and summed for comparison against a threshold current to indicate whether or not a subscriber station on the loop is off hook. Threshold current magnitude is variable to accommodate loop start and ground start applications. When the off-hook state is detected, the origination scan circuit is disabled by switching open the resistive part connections, and loop current is thereafter provided by other suitable means. Automatic current limiting arrangements are included for converting the switching functions to high impedance circuit elements.

Low resistance origination scan circuit

The present invention relates to a circuit capable of providing a negative temperature coefficient greater than that provided by discrete silicon integrated circuit components. A constant current source and a resistor divider network are added to a bipolar junction transistor, where the resistors and the constant current source function to increase the negative temperature coefficient of a bipolar junction transistor. The negative temperature compensation circuit formed in accordance with the present invention provides a sufficient negative temperature coefficient to offset the large positive temperature coefficient associated with high voltage avalanche breakdown diodes without requiring a high voltage integrated circuit.

Temperature compensated semiconductor integrated circuit

There is disclosed a precision linear comparator for a speakerphone circuit having two rectifying constant voltage nodes for separately summing two groups of signals derived from a speakerphone transmit channel and receive channel and supplying at an output terminal a signal representative of the difference between two unblocked summed signals. Each node blocks its summed signal if the signal is not representative of a true voice signal. A null signal is supplied at the output terminal during the absence of unblocked summed signals.

Speakerphone linear comparator

There is disclosed a circuit, using integrated techniques, for dividing the AC component of an input signal by the DC component of that signal and then muitiplying the signal by a fixed DC current. This circuit is useful in opto-coupled gain control devices where the output AC signal must be gain adjusted for the light transfer characteristics of the opto-couplers.

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Reading, PA, United States of America

Milton L Embree