Abstract: In an input circuit for high-frequency amplifiers having four transistors of the same conductivity type, the emitters of the first and second transistors (T1, T2) are connected to a reference point (M). The base of the first transistor (T1) forms the input (A) of the circuit and the base of the second transistor (T2) is connected to the collector of the first transistor (T1). The collector of the first transistor (T1) is connected to the emitter of the third transistor (T3) and the collector of the second transistor (T2) to the emitter of the fourth transistor (T4). The bases of the third and fourth transistors (T3, T4) are connected to one another, and at least one of the collectors of the third or fourth transistors (T3, T4) is connected to a current supply (I3, I4).

Abstract: A matching circuit is connected between a source circuit and a load circuit. The matching circuit is made up of an impedance transforming circuit and a balance-to-unbalance signal-transforming circuit. If necessary, means for blocking the DC components intervene between those transforming circuits. The impedance transforming circuit is made up of inductive and capacitive elements. The matching circuit is reversible.

Abstract: A switched-capacitance amplifier has a common terminal and an input signal terminal for receiving an input signal voltage therebetween, and it has an inverted output signal terminal for supplying, during each of a second series of separated time intervals interleaved without overlap with a first series of separated time intervals, an output voltage that is the negative of its input signal voltage. The switched-capacitance amplifier includes first and second capacitors. The switched-capacitance amplifier also includes a differential-input amplifier, having an output connection to the inverted output signal terminal, having a non-inverting input connection to the common terminal, having an inverting input connection, and having an input port between its non-inverting and inverting input connections.

Abstract: An in-phase hybrid and a balun in a single stage built with inexpensive coaxial cable which splits or combines RF power and simultaneously performs a balanced-to-unbalanced impedance transformation.

Abstract: A single input, differential output amplifier (50) includes two Gallium Arsenide field effect transistors: one arranged to form a common gate amplifier (55) to provide a non-inventing output (60), and the other arranged to form a common source (65) amplifier to provide an inverting output (61). The input of each FET is connected to receive an input signal simultaneously thereby minimizing phase delay in the differential output signals. In another aspect of the invention, the non-inverting stage (55) is incorporated into the biasing network for the inverting ampllifier (65).

Abstract: An amplifier system having an input active device at its first input and having its second input provided through an inverting means to that first input.

Abstract: A differential to a single-ended converter circuit includes linearizing PN junctions that compensate for input signal voltage loss in the input stage. A variable voltage source and a resistor are provided for adjusting the voltage produced across these junctions by varying the current through these junctions. The converter circuit also includes a shunt feedback amplifier for inverting half the differential output voltage so that it sums with the differential voltage of opposite phase to produce the single-ended output signal. The shunt feedback amplifier is operated at a constant current to minimize error voltages. Bootstrapping is employed to linearize thermal distortion of the PN junctions and means are provided for compensating for the resulting thermal distortion.

Abstract: A circuit which converts differential outputs of a fully differential amplifier to a single output using a buffer amplifier is provided. The fully differential amplifier has common-mode feedback provided by a differential feedback stage. An input of the common-mode differential feedback stage is connected to a predetermined one of the differential outputs to maintain the predetermined output at a reference voltage potential. The buffer amplifier uses diffused or well resistors and a single-ended differential amplifier. The buffer amplifier has a balanced structure which minimizes noise and resistor nonlinearity output errors. The circuit also maintains excellent power supply rejection.

Abstract: A transistor circuit is provided with a symmetrical floating configuration for attaining multifunction operation of a transistor having symmetrical source and drain characteristics, preferably a GaAs MESFET. The circuit includes a balun which may be configured as a transformer, a differential amplifier, or a magic-tee waveguide depending on the frequency of signals to be processed by the circuit. Balanced terminals of the balun may be directly or capacitively coupled to source and drain terminals of the transistor. Tuning circuits are employed for applying signals having different frequencies to the transistor and for extracting intermodulation products generated by the transistor in response to the signals at the different frequencies. With the direct connection between the balun and the transistor, alternating voltages may be impressed between the terminals of the transistor to alternate source and drain regions of the transistor.

Abstract: An active differential load circuit which receives a differential input signal applied to first and second inputs thereof and produces a single ended output signal at an output thereof while unwanted higher frequency signals applied thereto are filtered from the output without ground currents. The load includes a pair of transistors which have, in the preferred embodiment, their collectors connected together via series connected first and second resistors with the interconnection between the two resistors being connected to the bases of the two transistors. The collectors are also respectively coupled to a pair of current sources and the respective emitters receiving the applied differential input signal. A filter capacitor is coupled between the collectors of the two transistors and efffectively shorts the unwanted higher frequency signals thereacross.

Abstract: A two amplifier subscriber line interface circuit that uses a novel voltage divider technique for providing power to the two lower voltage amplifiers from a 50 volt central office battery. This is achieved by using one lower power amplifier with a Zener regulator diode in shunt thereof to regulate its current.

Abstract: A classical differential amplifier provides outputs of unequal magnitude due to its emitter resistance being finite. In order to equalize its output, a voltage follower circuit is associated with each of the inputs of the differential amplifier. The output of each voltage follower circuit is converted to a current and subtracted from one of the outputs of the differential amplifier. Subtracting the outputs results in a differential amplifier with both outputs being substantially equal.

Abstract: A differential output is provided from a single-ended input by a switched-capacitor stage having a through-switched capacitor coupled via an amplifier to one output terminal and a diagonally-switched capacitor coupled via an amplifier to another output terminal. Each amplifier is provided with a through-switched negative feedback capacitor. A delay inherent in the switching of the diagonally-switched capacitor provides an interpolation effect in the differential output.

Abstract: A signal converting circuit for converting a single-ended input signal to a pair of differential output signals includes a current source for generating a constant current; an input signal generating circuit for generating an input signal current; a first path including at least one diode connected to the current source and the input signal generating circuit for producing a first differential current as a function of the constant current and the input signal current; a second path including a series combination of a diode and the collector-emitter path of a transistor connected to the current source and the input signal generating circuit for producing a second differential current as a function of the constant current and the input signal current, the transistor being supplied with a current at its input; a differential amplifier output circuit having two transistors connected to the first and second paths for producing differential output signals in response to the first and second differential currents; a

Abstract: The circuitry comprises a source of input signal current, a common-base transistor amplifier or its equivalent supplying a first load means from its output connection, a first resistive means connected at its first end to the source of input signal current and at its second end to the input connection of the common-base transistor amplifier or its equivalent, a voltage follower with input connection from the first end of the first resistive means, a current mirror amplifier supplying a second load means from its output connection, and a second resistive means connected at its first end to the output connection of said voltage follower and connected at its second end to the input connection of the current mirror amplifier.

Abstract: A sound amplifier is provided in a monolithic integrated circuit form and includes tone compensated volume control achieved by the use of emitter followers and a capacitor connected at one side to ground.

Abstract: A balancing amplifier comprising a pair of transistors arranged as a differential amplifier and a negative feedback network including a transistor voltage follower as a part of the load circuit of each transistor of the pair of transistors. Owing to the negative feedback network high level signals can be balanced. The amplifier provides output signals in phase opposition from a single-ended input signal.

Abstract: A linear differential amplifier comprises two main transistors of one conductivity type (e.g. PNP) having emitters connected via a common constant-current generator to an ungrounded terminal of a d-c supply whose grounded other terminal is connected to their collectors via a pair of identical resistors; the base of one of these transistors is grounded while the base of the other transistor receives an a-c input signal. An unbalanced output signal is taken off the collector of an ancillary transistor of the opposite conductivity type (NPN) which is fed from the ungrounded supply terminal through a complementary auxiliary transistor or through another constant-current generator; the emitter of this output transistor is connected directly to the collector of the second main transistor.

Abstract: A circuit that is particularly adapted to convert a single-ended input signal to a pair of differential output signals. First and second series circuits are connected in parallel, the first series circuit being formed of first and second diodes and the second series circuit being formed of a third diode connected with the collector-emitter circuit of a transistor. The base electrode of the transistor is connected to the junction defined by the first and second diodes such that the base-emitter circuit thereof is in parallel arrangement with the second diode. A current source is connected to the parallel-connected series circuits so as to supply currents thereto. An input signal is supplied to the junction defined by the first and second diodes; the first and second outputs are coupled to this junction and to the collector electrode of the transistor, respectively, for providing differential output signal currents that are a function of the supplied signal.

Abstract: A symmetrical amplifier comprising two transistors having their emitters connected to ground via two resistors of equal value. An input signal is applied between the bases of the transistors and an output signal is available at the collectors of the transistors. This amplifier will provide improved linearity up to an input voltage of 200 mV if, for the emitter resistor, the relationship R.apprxeq.0.56 U.sub.T /I.sub.CO is satisfied, U.sub.T being the thermal voltage and I.sub.CO the collector quiescent current. The value of this resistor is very small so that the slope is reduced only slightly by the emitter resistors and the sensitivity of the circuit is hardly affected thereby.

Abstract: Amplifier for aperiodic signals with a base-coupled and an emitter-coupled differential amplification stage in which the emitters and the bases of the two differential amplification stages respectively form an input of which one can be charged with a signal and the respectively other one is capacitively grounded; a third input lies at the directly coupled emitters of the emitter-coupled differential amplification stage; the collectors of both differential amplification stages are cross-coupled; the bases of the base-coupled differential amplification stage is connected to supply potential with a series resistor; static dc currents are fed into the inputs so that a current of the same magnitude flows over the inputs at the bases and emitters of the differential amplification stages and a current of double magnitude flows over the third input.

Abstract: An elastic surface wave filter including on the surface of a plate, an emitting transducer, a surface wave coupler, and means for receiving the waves radiated by the coupler. The means for receiving includes two transducers each having two terminals with one terminal of each being in common with one terminal of the other. The common terminal serves as a phase reference and the voltages induced at the remaining terminals are in phase opposition to one another in the transmission band of the filter.

Abstract: A balanced-to-single-ended signal converter includes a pair of transistors of the same conductivity type responsive to balanced signals applied to their respective base electrodes to provide a single-ended signal at the interconnection of their serially connected collector-to-emitter paths.

Abstract: In an amplifier comprising a signal-amplifying circuit for amplifying an input signal to the amplifier and a power-supply circuit for supplying power to the signal amplifying circuit for operation, there is provided an additional amplifying circuit driven by the output signal of the signal-amplifying circuit and powered from said power circuit. Changes in the power-supply currents for the respective amplifying circuits cancel each other. Thus, the total current supplied from the power supply circuit is maintained constant.

Abstract: The voltage-to-current converter includes first and second transistors having their respective common electrodes arranged to receive between them the voltage to be converted to current. Their output electrodes have connections to first and second current supply means, as well as direct coupled feedback connections to their respective input electrodes. At least one of these feedback connections is via the follower action of a respective further transistor between its input and common electrodes, and converted output current is available at the output electrode of each further transistor. First and second resistances connect the common electrodes of said first and second transistors to a node supplied quiescent current by a third current supply means, and their combined resistance controls the voltage-to-current conversion gain.

Abstract: Improved input filtering apparatus for loudspeaker systems, and loudspeaker systems including such apparatus. The bass roll-off point of input filtering apparatus for loudspeakers is automatically adjusted to an optimum in accordance with the amplitude and spectral content of the audio signal being received at the time, thereby attenuating components in the signal liable to cause "bottoming" of the loudspeaker.

Abstract: The disclosed unbalanced-to-balanced signal converter circuit includes two pairs of transistors, each pair having first and second transistors with the base-to-emitter junctions of each pair being connected in series between a reference potential point and a constant current source. A driver circuit is arranged to supply an unbalanced input signal which increases the conductivities of the first transistor of the first pair and the second transistor of the second pair, while decreasing the conductivities of the second transistor of the first pair and the first transistor of the second pair, and vice versa. Balanced linear output signals are provided at the collectors of the second pair of transistors. A gain controlled amplifier and a capacitance control circuit each including the unbalanced-to-balanced converter are also disclosed.