Abstract: A single-turn loop antenna suitable for inclusion within the cabinet of a television receiver has at least one gap forming a pair of feed terminals. Circuitry connects to the feed terminals for tuning the antenna over at least a portion of the television frequency bands and for coupling signals from the feed terminals to a transmission line. The circuitry provides isolation so the tuning of the antenna by the tuning circuitry is unaffected by the impedance of the transmission line or its terminating impedance and variations thereof. The circuitry is affixed to the loop proximate to the feed terminals, and the transmission line is affixed to the periphery of the loop and departs therefrom at a neutral point located, for example, opposite to the gap.

Abstract: Tuning circuitry for a VHF television (TV) antenna tunes such antenna for signals corresponding to the TV channel selected and couples those signals to the tuning system of a television receiver. An antenna has a pair of signal terminals across which the tuning circuitry connects to form a resonance circuit therewith for tuning the antenna. A variable capacitance responds to a control voltage to develop the appropriate value of tuning capacitance. Impedances, e.g. inductors or capacitors or resistors, are coupled to the resonance circuit at least at selected times by switches. An amplifier couples signals from the resonance circuit to the tuning system of the TV receiver.

Abstract: An operational amplifier includes first and second differential-input amplifiers of complementary conductivity type, each such differential-input amplifier including first and second transistors in long-tailed pair configuration having their drains connected to third and fourth transistors connected in current mirror amplifier configuration. An output amplifier includes a pair of complementary conductivity type transistors, each in common-source configuration, to supply signals to an output terminal. One output of the long-tailed pair and the output connection of the current mirror amplifier in the first differential-input amplifier directly connect to the gate of the first common-source amplifier. One output connection of the long-tailed pair and the output connection of the current mirror amplifier of the second differential-input amplifier directly connect to the gate input of the other common-source amplifier. A tail current supply for each long-tailed pair establishes its quiescent operating point.

Abstract: A correction network for a bow-shaped temperature characteristic includes a resistor and a semiconductor junction having different temperature coefficients and operated with related potentials thereacross to generate temperature-dependent currents responsive to an input current. That temperature-dependent current is subtractively combined with a reference current of predetermined value so that a corrective current, the magnitude of which is usually substantially zero at a predetermined temperature and is temperature-dependent at either higher and lower temperatures, respectively, is generated. In a particular embodiment, a first such corrective current is applied to a node of an extrapolated band-gap voltage reference circuit to tend to reduce the degree to which the reference potential departs from a desired value at temperatures higher than the predetermined temperature.

Abstract: A protected transistor in an electronic circuit receives base drive current and has its collector-emitter path coupled to a source of collector-emitter potential and to a load. Overcurrent protection therefor is provided by a first, complementary conductivity type transistor connected base to emitter and emitter to base with the protected transistor, and thermally coupled thereto, to develop a collector current responsive to the collector-emitter current of the protected transistor. A comparator provides an overcurrent indication whenever the collector current of the first transistor exceeds a predetermined level. The overcurrent indication prevents further increase in the base drive current to the protected transistor. A further feature of the invention reduces the predetermined level in response to increasing collector-emitter potential of the protected transistor.

Abstract: Compensation for the current flowing in the collector resistance of a transistor is achieved by generating a compensating current of appropriate magnitude and polarity sense, and applying that compensating current to the base of the transistor. To this end, a voltage equivalent to that across the transistor emitter-collector path is applied across a current conductive device representative of the collector resistance. The current therethrough is then proportioned by a current amplifier and applied to the base of the transistor to be compensated.

Abstract: An amplifier circuit, having voltage gain responsive to a control signal, includes a transistor stage having a transistor and a load, and an amplifier stage in cascade connection, and a control transistor connected to the transistor. The control signal varies the collector current of the transistor via the control transistor whereby the voltage gain of the transistor stage correspondingly varies. Degenerative feedback couples the output to the input for stabilizing the quiescent output potential so that the amplifier circuit is susceptible of being direct coupled to subsequent circuits.

Abstract: A folded-cascode amplifier arrangement includes first and second transistors of complementary conductivity type and a constant current generator for supplying quiescent current thereto. Signal current flowing in the first transistor is coupled to the second transistor through current steering at the interconnection between their main conduction paths. The load means for the second transistor includes a cascode-connected third transistor for supplying load current thereto, which third transistor substantially increases the resistance of the load for correspondingly increasing the voltage gain of the amplifier arrangement. The amplifier voltage gain transfer function exhibits a frequency response dominated by a single pole.

Abstract: A folded-cascode amplifier arrangement includes first and second transistors of complementary conductivity type and a constant current generator for supplying quiescent current thereto. Signal current flowing in the first transistor is coupled to the second transistor through current steering at the interconnection between their main conduction paths. Signal current flowing in the first transistor is further coupled to the input circuit of a current mirror amplifier (CMA), the output current of which is proportional to the signal current and is coupled to the main conduction path of the second transistor. The output current of the CMA is poled for reinforcing the current flow of the second transistor so that the output current available from the folded-cascode configuration is substantially greater than the signal current in the first transistor. The amplifier voltage-gain transfer function exhibits a frequency response dominated by a single pole.

Abstract: A plural-stage amplifier circuit having improved common-mode input voltage range includes first and second transistors connected to form a first long-tailed pair, third and fourth transistors connected to form a second long-tailed pair in cascade connection after the first long-tailed pair, a first current supply providing tail current to the first long-tailed pair, a second current supply having a plurality of outputs providing collector currents to the first long-tailed pair, and a third current supply providing tail current to the second long-tailed pair. The output currents of the first, second and third current supplies are controlled in proportion to a control current which permits the voltage across the third current supply to be controlled such that the first and second transistors do not saturate at input voltages approaching the supply voltage.

Abstract: An amplifier including two long-tailed-pair configurations in cascade: the first including a pair of bipolar transistors having input signals coupled to their respective bases, their emitters connected to a source of quiescent operating current, and their collectors connected to respective constant current generator loads; and the second including a pair of field-effect transistors having gate electrodes coupled to receive signals from the respective collectors of the first and second bipolar transistors, their source electrodes connected to a source of quiescent operating current, and their drain electrodes connected to subsequent circuit means for deriving an output from at least one of them. By this arrangement substantially the maximum available voltage gain is obtained from the first long-tailed pair. The amplifier may be used as the input circuitry of an operational amplifier, for example, and is suitable for monolithic construction.

Abstract: A signal detection system, of a type suitable for use in line scanning or character recognition apparatus, for providing substantially invariant output signal waveforms in response to repetitive input signals superimposed on pedestal levels. The input signals and pedestal signals may vary substantially. The signal detection system includes a forward signal path including apparatus for amplifying and slicing the input signals, a degenerative feedback path including apparatus for generating a balance signal which is proportional to the amplified difference between an average of the output signals and a reference level, and, the detection system also includes apparatus for subtractively applying the balance signal to substantially eliminate the effects of the pedestal signals on the output waveform.