Abstract: A thermally regulated amplifier system includes an amplifier unit, a temperature-sensing unit and a controller. The amplifier unit includes a power amplifier that has an adjustable gain function. The controller receives temperature readings from the temperature-sensing unit, computes the gain G(n) of the amplifier unit, and provides the computed gain of the amplifier G(n) to the power amplifier unit.
Abstract: The antenna amplifier for mobile FM radio reception includes a signal amplifier, a controllable adjusting element having a PIN diode for impedance adaptation, and a control amplifier for regulating the adjusting element. The antenna amplifier has a compensation for the temperature response occurring as a result of very great differences (summer/winter) in ambient temperature, the PIN diode connection point is optimized, and the control range is maximized.
Abstract: In a signal read circuit including a plurality of circuit rows each having a charge amplifier connected to a photoelectric conversion element PD and a CDS circuit 2S for performing correlated double sampling for an output from the charge amplifier, a dummy circuit row DMY having the same configuration as a circuit row SLT is connected in parallel with this circuit row SLT. By calculating the difference between these circuit rows connected in parallel, offset variations generated in the two circuit rows SLT and DMY can be removed.
Abstract: A diode detector that is stable and linear over a wide range of variations in both temperature and power supply voltage and can be used to regulate a.c. signals produced by devices that are responsive to control signals includes a detector diode and a first resistor in series, a capacitor connected between the junction of first resistor and the detector diode and a reference potential, and a compensator diode and a second resistor in series with each other and with the detector diode and first resistor. An input a.c. signal is provided to a first terminal of the detector diode, and a rectified signal is provided at the junction of the detector diode, the first resistor, and the capacitor. The detector diode and the compensator diode have temperature coefficients that are substantially the same, and those diodes have the same polarities.
Abstract: A dummy load for a radio frequency transmitter uses a resistive liquid within a tube of non-conducting material as the load. The tube has grounded conductors at each end, and a centrally-located terminal that provides a load, with respect to ground, across two parallel branches. The output of the radio frequency transmitter is applied between the centrally-located terminal and ground. The ends of the tube are connected into a closed liquid loop that includes a temperature controlling system with a circulating pump, a heater for raising the temperature of the resistive liquid to a given, operating level, if necessary, and a heat exchanger for lowering the temperature of the resistive liquid to the given, operating level, when necessary; whereby the heat generated by the output of the transmitter can be dissipated, and the temperature of the resistive liquid, within the tube, kept at a constant mean temperature to provide a constant resistance under all load conditions.
Abstract: A logarithmic amplifier which obtains accurate logarithmic output voltage and expands maximum current value and which realizes accurate logarithmic conversion by eliminating logarithmic conversion error voltage resulting from internal resistance of logarithmic conversion element using a voltage appearing when a forward current of logarithmic conversion element is applied to a resistor.
Abstract: Herein disclosed is a variable gain amplifying circuit which comprises a heating element, a heat-sensitive resistance coupled thermally to the heating element, an amplifier including the heat-sensitive resistance, and means for controlling the heat of the heat element. This heat of the heating element is controlled so as to control the value of the heat-sensitive resistance. As a result that the value of the heat-sensitive resistance is controlled, the gain of that amplifier is controlled.
Abstract: A resistance thermometer in which a temperature sensing resistor is connected in parallel with a series combination consisting of a signal output resistor and a compensating resistor. By choosing the resistance ratio between two resistors to be equal to the ratio of the desired resistance value to the error of the temperature sensing resistor, the output voltage developed on the signal output resistor reflects the voltage expected on the temperature sensing resistor without the resistance error thereof. The temperature sensing resistor and the compensating resistor constitute a circuit unit which is detachable from the rest of the resistance thermometer.
Abstract: A temperature compensating voltage generator circuit for compensating temperature characteristics of an electric circuit whose electrical characteristic varies in accordance with the change of the ambient temperature and whose electrical characteristic can be changed or controlled by a control voltage. The temperature compensating voltage generator circuit comprising a plurality of temperature sensitive resistor circuits, a plurality of diode circuits and one or more resistor circuits. A temperature compensating voltage from the temperature compensating voltage generator circuit being independently adjustable at each predetermined temperature.
Abstract: A power transistor in the final stage of an IC amplifier feeding a reactive load, such as a loudspeaker, has an emitter resistor connected across the input of a heat-sensitive monitoring transistor by way of a diode in bucking relationship with its base/emitter path, the monitoring transistor being part of a protective circuit which reduces the input signal to the power amplifier in the event of an overload. The monitoring transistor is separated from the power transistor, on the silicon chip of the amplifier, by a distance so chosen that an overload raising the temperature of the power amplifier will significantly reduce the operating threshold of the monitoring transistor only if the overload persists for a minimum period on the order of one millisecond.
Abstract: Circuitry for compensating for the effects of changes in ambient temperature on an automatic gain control arrangement in a missile-borne receiver is shown to include an operational amplifier responsive only to the level of the output signal from an automatic gain detector and amplifier, such end being effected by using temperature sensitive elements in the input and feedback circuits of the operational amplifier.
June 5, 1978
Date of Patent:
January 22, 1980
William C. Brown, Jr., Paul G. Crete, Philip L. Sullivan, James Williamson
Abstract: The present invention concerns the transmission of information, and consists in a continuous regulator responsive to the amplitude of a pilot tone included in the signal whose level is to be regulated, including a variable-gain quadripole through which said signal is passed, an automatic gain control loop including a circuit controlling the gain of the quadripole, and an auxiliary feedback loop through which the control circuit also controls the automatic gain control loop. The regulator is applicable with advantage to transmission systems.
November 15, 1977
Date of Patent:
September 4, 1979
Compagnie Industrielle des Telecommunications Cit-Alcatel
Abstract: A power transistor in the final stage of an IC amplifier feeding a reactive load, such as a loudspeaker, has an emitter resistor connected across the input of a monitoring transistor by way of a diode, the monitoring transistor being part of a protective circuit which reduces the input signal to the power amplifier in the event of an overload. To retard the response of the protective circuit, for the purpose of preventing signal distortions in the event of brief power surges, the diode and the monitoring transistor are so disposed on the silicon chip of the amplifier that a thermal wave from the overheating power transistor will first strike the diode, thereby reducing its resistance to compensate for an increased voltage drop across the emitter resistor, and will reach the monitoring transistor with a certain delay; if the overload persists, the resulting increase in the conductivity of the monitoring transistor re-establishes the full sensitivity of the protective circuit.
Abstract: A method and circuit for protecting the output stage of an amplifier from thermal overload. A normally-open, temperature sensitive switch is thermally coupled to the transistors in the output stage and electrically connected across a portion of the feedback resistance element of the amplifier, in one circuit embodiment. Whenever the temperature of the transistors reaches a predetermined threshold level, the switch closes and acts as a low resistance path across that portion of the feedback resistance element, thereby reducing the gain of the amplifier to a safe level which is zero in the preferred embodiment. Thereafter, when the temperature decreases below the predetermined threshold level, the switch automatically opens to restore normal operation of the amplifier.
Abstract: Power limiting circuitry for use with a power amplifier, the power amplifier having (a) a power supply voltage source connected thereto and (b) a load impedance, the power limiting circuitry comprising detecting means for detecting the magnitude of the load impedance; and control means responsive to the detecting means for controlling the magnitude of the power supply voltage applied to the power amplifier; means for sensing the temperature at a predetermined point in the power amplifier and generating an output signal when the temperature exceeds a predetermined amount; and AND circuit means responsive to the detecting means and the temperature sensing means for actuating the control means in response thereto.
Abstract: A Class AB linear power amplifier circuit is connected in a balanced bridge configuration for increasing the fidelity and power output from stereophonic sound systems, such as used primarily in automotive vehicles, the circuitry consisting of a series of NPN transistors and PNP transistors, with bias for the transistors provided by a power source, a series of resistors and thermistors, an optional input overload protection circuit, with the transistors further being matched and balanced so as to effectively double or quadruple output power as would be available from a single ended configuration, so that the amplifier circuitry operates in a Class A mode to eliminate any crossover distortion.
Abstract: A normally-closed temperature sensitive switch which is heat coupled to the output transistors of an amplifier, is connected in series with a zener diode and the operating coil of a relay. When the voltage applied to the series circuit, which is the same voltage as applied to the amplifier, is insufficient to cause breakdown of the zener diode, the relay remains inactivated, and a pair of relay contacts across a feedback resistor of the output transistors remains closed. This keeps the output transistor off so that transients (which are the response of the amplifier to the rapid change in operating voltage when the amplifier is first turned on or when it is turned off) are substantially reduced. When the voltage reaches a given level at or close to the nominal operating voltage level, the relay is activated and the output transistors are turned on. When the temperature reaches a value such that the switch opens, the relay is inactivated and the output transistors are thereby turned off.
December 8, 1975
Date of Patent:
October 18, 1977
Miroslav Glogolja, Charles Brook Leuthauser
Abstract: In a transmitter designed for periods of extended use, means for sensing the ambient temperature in which the transmitter would operate if activated and adjusting the initial output power of the transmitter so as to reduce the initial output power of the transmitter to maximize or increase the power output above that obtainable using existing protective techniques over an extended period.
Abstract: An electronic circuit for automatically controlling gain and roll-off in wide-band amplifiers for use in tele-distribution systems including a feedback network with a negative temperature coefficient pure ohmic resistance feedback. When automatically controlling roll-off, a second negative temperature coefficient resistance is placed in series with an inductance.