Abstract: Series connected field-effect transistors (FET's) of complementary conductivity types are employed to mix two input signals. The transistors are biased in their linear operating region and operate as common source amplifiers for the signals to be mixed. The input signals are applied to the respective gate electrodes of the transistors and the output signal containing upper and lower sideband frequencies is available at the common drain connection of the transistors.

Abstract: Each circuit responds to an input current with an output current in fixed ratio to its input current despite variations in the absolute temperature T at which its input and output transistors are operated. Input current from a two-terminal current regulator of a particular type is employed to develop across a resistance a voltage V which varies as a function of T. The input current passing through the resistance serves as the emitter-to-collector current of the input transistor, which is self-biased. The voltage V is applied between the bases of the input and output transistors of the current amplifier for producing the desired output current at the collector of the output transistor.

Abstract: A three-terminal current amplifier with current-mode feedback to stabilize its current gain to be substantially independent of the common-emitter forward current gains of its component transistors. The feedback connection is made by means of a current splitter which includes a pair of emitter-connected transistors operated at substantially the same absolute temperature, T. These transistors have a potential substantially linearly proportional to T applied between their base electrodes. The current-amplifier output terminal is coupled to the interconnected emitter electrodes of the transistors and the collector electrode of the first transistor is coupled to the current-amplifier input terminal.

Abstract: A potential offset is developed across a self-biased transistor responsive to applied input current. This offset potential has a decrement subtracted therefrom by a network comprising an intermediate transistor and a pair of resistors; this reduced potential provides the base-emitter potential for biasing the base-emitter junction of a transistor supplying output current between its emitter and collector electrodes. Very large current attenuation factors are obtainable with resistors having sufficiently low resistance as to be readily integrable in a monolithic integrated circuit.

Abstract: Current mirror amplifiers, each using a field-effect transistor as a source follower to provide collector-to-base feedback to a first bipolar transistor to condition its collector-to-emitter path to accept an input current. A second bipolar transistor has its base-emitter circuit parallelled with base-emitter circuit of the first bipolar transistor which conditions the collector-to-emitter path of the second bipolar transistor to conduct an output current proportionally related to that in the collector-to-emitter path of the first bipolar transistor. Since the source follower supplies the base currents of the bipolar transistors without requiring any gate current, the ratio of the input to output currents is constant regardless of the current gain of the bipolar transistors.

Abstract: A first transistor of a first conductivity type connected as a common-base amplifier in the collector-to-base feedback connection of a second transistor of a second conductivity type, complementary to the first conductivity type, exchanges base current with a third transistor of the second conductivity type. The collector current of the third transistor is proportional to that of the second transistor by a factor substantially equal to 1/h.sub.fe, where h.sub.fe is the common-emitter forward current gain of the first transistor.

Abstract: Phase-splitter circuits making use of the properties of "long-tailed pair" configurations. Each such pair comprises first and second transistors connected to one another at their emitter electrodes and exhibiting an input impedance between their respective base electrodes. In the present circuits, a pair is driven by a signal source having relatively high source impedance between the base electrodes of the transistors.

Abstract: A bridge-output amplifier, comprising four transistor means connected in bridge responsive to a drive signal to supply opposite ends of a cross-arm load with push-pull output signals, has direct-coupled differential mode feedback to reduce the quiescent potential applied across the load. This feedback is provided by a difference amplifier having the push-pull output signals applied to respective ones of its inverting and non-inverting input circuits and supplying a feedback signal at its output circuit. This feedback signal is used to improve the balance of the bridge.

Abstract: A current mirror amplifier circuit with an input current path and an output current path is further provided with a sensing means responsive to the cessation of current flow in the output current path such that the cessation of current flow in the output current path causes the current flow in the input current path to be discontinued.

Abstract: PNP composite transistors connected as commonemitter amplifiers each comprise a PNP pre-amplifier transistor in direct coupled cascade with a plurality of parallelled NPN transistors. The emitter-electrode of the PNP transistor is connected to a sensing resistor in the collector path of one of these NPN transistors, causing the "base-to-emitter" potential of the composite transistor to increase if its "emitter" current exceeds a threshold current. By clamping this base-to-emitter potential if it exceeds a predetermined potential, the output current of the composite transistor is prevented from becoming excessive. This predetermined potential is controlled as a function of composite transistor temperature and supply potential to provide the required degree of over-current protection for these particular conditions.

Abstract: A neutral ground fault detector couples oscillations from a local oscillator into the neutral conductor of an electric power transmission system whenever a ground-fault appears thereon. Oscillations appearing on the neutral conductor during ground-fault conditions are synchronously detected by homodyning them with oscillations obtained directly from the local oscillator, thereby to otain a direct-current indication of the ground fault on the neutral conductor.

Abstract: Successively larger fractions of a first composite signal are compared with an entire second composite signal to obtain control signals. The composite signals comprise similar direct components with push-pull a-c signals superimposed thereon. One of these control signals may be used to standardize the average amplitude of the push-pull signals by causing them to be attenuated when they exceed a given amplitude, and at least one other, for controlling the synchronous regeneration of the a-c signals. The invention is useful for PCM repeaters in telephone cables.

Abstract: Unbalance currents in a-c power line conductors are sensed by a differential current transformer. They are then synchronously detected at the line frequency. A substantial direct current component in the detected signal is indicative of a resistive ground-fault and distinguishes such a fault from other types of unbalanced loading of the a-c power line conductors, such as unbalanced-capacitance-to-ground conditions.

Abstract: A three-terminal current amplifier having a current gain substantially independent of the forward current gains of its component FET's. First and second FET's have source electrodes connected to the common terminal of the amplifier. A third FET has its source electrode connected to the second FET drain electrode and has its gate and drain electrodes connected to the input terminal and the output terminal of the amplifier, respectively. The gate electrodes of the first and second FET's and the first FET drain electrode are coupled to the input terminal by a potential source providing an offset potential smaller than the source-to-gate potential of an FET, which permits the potentials required between the common terminal and each of the input and output terminals to be reduced as compared to prior art FET amplifiers of this sort.

Abstract: A current mirror amplifier is supplied input current through the terminal conventionally common to its input and output circuits, which input current is split into two portions related as the gain of the current mirror amplifier. Either or both of these portions may be utilized as an output current.

Abstract: The collector potential of a resistively loaded common base amplifier tends to change if its emitter current is altered to affect its emitter resistance and thereby control its gain. This tendency arises because of the change in transistor collector current, which is substantially the same value as the change in its emitter current, acting on the resistive load in accordance with Ohm's Law. A control current is applied to diode means to develop a potential thereacross, which is applied to the base emitter junction of the transistor to control its emitter current. This establishes a known proportion of control current to transistor emitter and collector currents. Changes in the transistor collector current are then compensated for by another current proportional to the control current applied at the transistor collector electrode, thereby to counteract the tendency for the transistor collector potential to change as the gain of the common-base transistor amplifier is changed.

Abstract: A differential amplifier stage, suitable for use as the first stage in an operational amplifier with a single power supply, has the capability of its input terminals being operated over a range including one of the supply potentials. The differential amplifier stage includes a pair of emitter-coupled transistors of a first conductivity type having their base electrodes connected to input signal terminals. These transistors are each provided with an active collector load by grounded-emitter transistors of the second conductivity type connected collector-to-collector therewith. Commonmode feedback from these collector-to-collector connections to the base electrode of the grounded-emitter transistors is used to regulate the emitter-to-collector potentials of these grounded-emitter transistors to a lower value than their emitter-to-base potentials, but to a value larger enough to avoid saturation.

Abstract: A common-emitter amplifier transistor has its gain controlled by change of its transconductance as a function of its quiescent emitter current. A first controlled current applied to a diode means develops a potential thereacross which is applied between the base and emitter electrodes of the amplifier transistor. This configuration causes the quiescent collector and emitter currents of the amplifier transistor to be in well-defined proportion to the first controlled current. This permits a second controlled current linearly related to the first to be used to counteract changes in the quiescent collector current of the common-base amplifier transistor, insofar as being coupled to the amplifier load.

Abstract: A diode OR gate permits trigger circuits of an array of SCR's to share the same integrating capacitor for suppression of short-lived transients, which might otherwise cause false triggering of the SCR's. The SCR's are switching and latching elements in a telephone cross-point switch array.

Abstract: First and second transistors have their emitter electrodes connected to receive operating current from the same supply. A current amplifier has its input circuit connected to sense the base current of the second transistor and its output circuit connected to supply base current to the first transistor responsive to the sensed current. This current amplifier connection stabilizes the quiescent collector currents of the first and second transistors to predictable values. Balanced output currents responsive to an input signal coupled to the first transistor base electrode are available from the collector electrodes of the first and second transistors.