Abstract: The present invention relates to a high output programmable current source. omplementary output stages are connected between appropriate power supply polarities for driving a low impedance load which is connected to circuit ground. An operational amplifier is connected between the input and emitter of each of the complementary stages providing negative feedback for virtually eliminating the input offset voltage of the respective output stage. A programmable function signal source is connected to the operational amplifiers for driving a programmable signal current to the extent possible through the load resistance from a limited voltage supply.

Abstract: A high frequency audio amplifier in which the positive and negative bias ports of an operational amplifier are employed to drive two oppositely phased current mirror circuits. Additionally, the outputs of the current mirror circuits are current regulated in terms of the number of base emitter voltage drops in power amplifier circuitry following the current mirrors. Further, the output stage employs parallel connected radio frequency type transistors.

Abstract: A driver amplifier circuit for an electromechanical position translator having two coils of substantially equal inductance and resistance is disclosed. The circuit includes an input for a control voltage representing desired translator position and a reference voltage, a very low value reference resistor series connected between the two coils, differentially driven push pull amplifiers connected to drive the coils, and two equal value feedback resistors connected from the reference resistor to inverting inputs of the amplifiers, whereby absolute magnitude of output voltage equals the input voltage plus twice the reference voltage, and wherein zero differential input volts yields zero current flow through the coils.

Abstract: A wideband recording amplifier having push-pull amplification stages in which each stage comprises a common-base configured transistor amplifier driving an emitter-follower configured amplifier and with a negative feedback signal being applied to the base inputs of the common-base configured amplifiers.

Abstract: A wide-band direct-coupled transistor amplifier exhibits greatly improved settling time characteristics as the result of circuitry permitting the use of current feedback rather than voltage feedback in order to reduce the sensitivity of settling time and bandwidth to feedback elements without thereby affecting the manner in which feedback is applied externally by the user, reducing the sensitivity of settling time to the effects of temperature, eliminating saturation and turn-off problems within the amplifier that are related to bias control, to large input signals, and to high frequency input signals or those having fast rise times, and minimizing the sensitivity of settling time to power supply voltages.

Abstract: A kinescope driver amplifier comprises a resistive feedback network coupled from the output to the input of the amplifier. The feedback network includes first and second series resistor of mutually different values. The larger value resistor is connected to amplifier output, and the smaller value resistor is connected to the amplifier input.

Abstract: A Class AB amplifier circuit includes bias circuitry for biasing the output transistor into partial conduction independent of the base-to-emitter voltage of the transistor. The bias circuitry is a simple circuit loop including the output transistor and forms the remainder of the amplifier circuit which can be fabricated in monolithic integrated circuit form. The loop comprises a differential amplifier for providing a substantially constant offset voltage across a pair of terminals between which is connected a current biasing component. The current biasing component is connected in series with the output transistor to produce a small quiescent current to flow therethrough, the value of which is independent of the transistor's characteristics.

Abstract: The present invention comprises an amplifier circuit (2, 1100, 1500, 1600) and transformer based power supply (24, 500, 700, 1710) wherein greater efficiency is achieved by using the input signal characteristics to control various aspects of the circuit operation. The transformer primary winding (8, 500a, 700a, 1710a) is energized by a pulsed power supply (6, 502, 702, 1702) which is duty cycle modulated in response to the signal being amplified. One embodiment of the amplifier employs output transistors (Q1101, Q1103, Q1105, Q1107, Q1109, Q1111) connected to respective stepped voltage levels. Amplifier control circuitry (1126, 1130, 1138, 1140) acts in relation to the input signal amplitude to more evenly distribute the voltage drop across the interconnected transistors (Q1101, Q1103, Q1105, Q1107, Q1111), thus reducing amplifier power requirements and minimizing distortion in the amplifier output.

Abstract: Negative-feedback circuit for a transistor amplifier having an output stage, an output transformer being operated by the output stage and having a center tap and two ends, the center tap being connected to a supply voltage source, a first output transistor connected to one of the two ends of the transformer and a second output transistor connected to the other end of the transformer, each of the output transistors being driven by a half wave of an information signal and being load carrying during that respective half-wave only, including two circuits, one being connected to the first output transistor and the other being connected to the second output transistor for imaging the current in the output circuit of the output transistors connected thereto, and a circuit branch connected to the imaging circuits for combining the currents flowing in the imaging circuits into a full-wave voltage signal for negative-feedback.

Abstract: A CMOS Class AB power amplifier is disclosed wherein supply-to-supply voltage swings across low resistive loads are efficiently and readily handled. A high gain input stage including a differential amplifier driving a common source amplifier drives unity gain push-pull output stage. Included in the invention is circuitry to control the DC bias current in the output driver devices in the event of an offset between the push-pull unity gain amplifiers.

Abstract: The disclosed operational amplifier comprises a first pair of complementary type transistors that have their emitter-collector paths connected in series across a source of reference potential. The emitters of the transistors are connected together and to an output terminal. A feedback resistance is coupled from the output terminal to the amplifier input. A second pair of complementary type transistors are similarly connected across said reference potential, with the emitters thereof connected together and to a second output terminal. A second feedback resistance is coupled from the second output to the amplifier input. A pair of resistors of predetermined values are respectively connected between the base electrodes of similar type transistors of the first and second transistor pairs. And a pair of constant current sources are respectively coupled to the base electrodes of the second pair of transistors.

Abstract: An amplifier with substantially no distortion is provided, the amplifier having input and output terminals and an amplification means for amplifying an input signal applied to the amplification means. A distortion detection circuit is provided for detecting distortion generated in the amplification means in accordance with the input and output signals of the amplification means. The output of the distortion detection circuit is applied to an addition circuit where the output of the distortion detection circuit is added to an input signal applied to the input terminal of the amplifier. The added signal is then supplied as the input signal of the amplification means for the cancellation of distortion generated in the amplification means.

Abstract: A power amplifier circuit comprises a class A amplifier having a pair of output amplifying devices responsive to an input for driving a load, a power supply connected between power supply terminals of the output amplifying devices for producing a voltage, and a class B power amplifier driven by the input to the class A amplifier. The class B power amplifier includes a pair of push-pull output amplifying devices having outputs connected respectively to the power supply terminals, and a pair of drivers for driving the push-pull output amplifying devices. The drivers have first controlled electrodes for driving the push-pull output amplifying devices and second controlled electrodes connected to a common potential point. A negative feedback loop may be connected for supplying signals dependent upon voltage changes at the power supply terminals back to an input stage of the class B power amplifier.

Abstract: This application discloses a virtual ground pre-amplifier for application with magnetic phono cartridges such as moving coil, moving magnet, moving iron, or similar types. The preamplifier according to the present invention comprises a forward path (an amplifier), and a reverse path (shunt feedback). By presenting a relatively low load impedance to the phono cartridge, the preamplifier effectively damps mechanical resonances of the stylus-cartridge system, and thus serves as a "stylus stabilizer."Also disclosed are techniques for equalizing the overall response of the stylus-cartridge-preamp system so as to provide a predetermined (e.g., flat) frequency response. This predetermined frequency response can be achieved by utilizing any of several circuit arrangements which serve to compensate for the intrinsic inductance and dc resistance of the magnetic phono cartridge.

Abstract: An audio power amplifier includes an input amplifier stage and an output power amplifier stage. The output power amplifier stage comprises a p-channel field effect transistor and an n-channel field effect transistor having interconnected drain electrodes forming an output signal terminal. A driver circuit is provided for driving the p-channel and n-channel field effect transistors in a transconductance mode of operation in which the output current through the field effect transistors is directly proportional to the input voltage applied to the output amplifier stage. A first feedback path is provided between the output power amplifier stage and the input amplifier stage. A second feedback path is formed between the output and input of the input amplifier stage.

Abstract: A circuit maintains the quiescent collector current of an output transistor amplifier constant by sensing the voltage developed across a resistor connected in series with the output transistor's collector and, using a differential amplifier, produces a first signal representative thereof which is sampled and held by a circuit controlled by a zero voltage crossing detector sensitive to the amplifier output voltage. The sampled and held signal is inverted and integrated with respect to an adjustable reference voltage to produce a second signal. The second signal controls the current passed by a transistor connected in a voltage divider network supplying the base bias voltage to the output transistor.

Abstract: The disclosed operational amplifier comprises a first pair of complementary type transistors (Q5, Q6) (of high current carrying capacity) that have their emitter-collector paths connected in series across a source of reference potential. The emitters of the transistors are connected together and to an output terminal (17). A second pair of complementary type transistors (Q3, Q4) are coupled across said reference potential, each transistor of said second pair being coupled across the similar conductivity type transistor of said first pair. A first pair of resistances (R1, R2) of predetermined value are respectively connected between the bases of the similar conductivity type transistors of said first and second pair. A second pair of resistances (R3, R4) respectively connect the emitters of the transistors of said second pair to said output terminal.

Abstract: An integratable amplifier is disclosed for developing a high level output signal with reduced power dissipation. The amplifier includes a first circuit (108, 110) which responds to an input signal for developing first and second signal currents whose amplitudes increase and decrease, respectively, in response to an input signal transition of a given direction. A second circuit (32a) receives the first signal current for establishing a third signal current which mirrors the first signal current. The second and third signal currents are received by a third circuit (70a) for conversion thereof to an amplified output signal. To stabilize the gain of the amplifier, a negative feedback path (50a) is coupled between the input signal and the output signal.

Abstract: Disclosed herein is a push-pull amplifier circuit employing field-effect transistors in which the field-effect transistors opposite in electrical conductivity to each other are activated by a common input signal to perform a push-pull operation. Secondary distortion components due to the square-law characteristics of the field-effect transistors are cancelled out by impedance elements each being provided between the source of each field-effect transistor and a common reference potential point.

Abstract: A biasing circuit for MOSFET power amplifiers in complementary pair push-pull single ended or bridge configuration. The biasing circuit includes a complementary pair of bi-polar transistors operating as common base amplifiers. Each amplifier includes emitter and collector resistances. A portion of the collector resistance of each common base amplifier acts as a gate-source biasing resistor for an associated MOSFET power transistor. The active feedback circuit is responsive to the voltage at a center tap of the primary winding of the amplifiers output transformer. The effect of the active feedback arrangement is to reduce the closed loop voltage gain of a conventional bridge amplifier from approximately 8.5 to approximately 0.9 thereby minimizing voltage fluctuations at the center tap of the primary of the output transformer.

Abstract: In a complementary single-ended push-pull amplifier in which emitters of first and second complementary bipolar output transistors are connected through first and second emitter resistors to a load such as a loudspeaker, third and fourth complementary bipolar transistors are connected in series between the bases of the first and second bipolar transistors having their emitters connected to a bias voltage source for operating the first and second output transistors in the Class A mode. The bases of third and fourth transistors are respectively connected to the emitters of the first and second transistors, whereby a negative feedback is provided from the emitters of the first and second transistors to the bases thereof. With this arrangement, the sum of the collector currents of the first and second transistors is kept substantially constant and hence distortion of an output current (difference between the collector currents of the output transistors) fed to the load at large signal levels can be improved.

Abstract: An amplifier is disclosed having a differential amplifier circuit, a current mirror circuit, a bias circuit and first and second single ended push-pull (SEPP) circuits connected in parallel to each other between a power source and earth. The first SEPP circuit includes a pair of diode-connected complementary transistors whose emitters are connected together and connected to the amplifier circuit. The second SEPP circuit includes a pair of diode-connected complementary transistors whose emitters are electrically insulated from those of the first SEPP circuit and connected to an output terminal of the amplifier. When a muting switch is opened, the supply of currents to the bias circuit is shut off, causing the first and second SEPP circuits to become unactuated and thereby attenuating an output signal from the output terminal of the amplifier.

Abstract: A class A complementary push-pull amplifier comprising first amplification means and second amplification means complementary in type to the first amplification means; first and second current detection means for detecting each output current of the first and second amplification means, each current detection means being coupled in serial relation with each other between output points of the first and second amplification means and a load of the push-pull amplifier being connected to a junction point of the first and second current detection means; comparator means for comparing a potential difference developed across the first current detection means and/or the second current detection means with a constant voltage to produce a control signal; and bias setting means for feeding bias current to the first and second amplification means in proportion to the control signal thereby to maintain the sum of output currents of the first and second amplification means constant.

Abstract: A system for generating and autocontrolling the voltage or current wave form in a process for the electrolytic coloring of anodized aluminium includes feeding power from a source of symmetrical direct current, with a neutral connection directly coupled to a load, while the positive and negative voltages supplied by the source pass through a power control stage which is controlled by a bipolar operational amplifier. The bipolar operational amplifier has two signal inputs, a positive or non-inverting input which is connected to a signal generator, and a negative or inverting input having a signal which corresponds to the signal which actually exists on the electrodes of the electrolytic bath. This signal is processed in a half-wave outer controller which is controlled by a programming system.

Abstract: Class AB push-pull amplifiers using a pair of complementary metal-oxide-semiconductor CMOS field effect transistors in source-follower connections in its driver stage and using a pair of non-linear current amplifiers with complementary conduction characteristics in its push-pull output stage.

Abstract: A power-amplifying circuit embodying this invention comprises a pre-amplifier for amplifying an input signal, a push-pull amplifier including first and second transistors driven in accordance with an output from the pre-amplifier, and a feedback circuit which detects output currents from the first and second transistors and supplies a current corresponding to a product of output currents from the first and second transistors to the pre-amplifier through a negative feedback path in order to regulate the quiescent currents of the first and second transistors. The push-pull amplifier is driven by a power source having a prescribed level of voltage. The feedback circuit and pre-amplifier are driven by an auxiliary power source whose voltage is obtained by adding through a bootstrap capacitor the output voltage from the push-pull amplifier to a referential voltage slightly lower than the power supply voltage by a resistor.

Abstract: A power-amplifying circuit includes a differential amplifier wherein the base of one of the transistors is supplied with an input signal and the collectors of both transistors are respectively supplied with signals amplified in the non-inverting form and the inverting form, two output transistors carrying out a push-pull operation upon receipt of output signals from both transistors of the differential amplifier, third and fourth transistors for detecting output currents from both transistors of the output transistors, and a circuit for supplying a current corresponding to a product of output currents from the first and second transistors to the differential amplifier through a negative feedback path. A compensation resistor is connected to one of the bases and emitters of the third and fourth transistors to counterbalance a parasitic resistance occurring in the first and second transistors.

Abstract: An amplifier comprising a first and a second amplifier element, whose outputs are connected to a load, a difference circuit which comprises a comparator, in which the output signal of the first amplifier element is compated with the input signal thereof to produce a correction signal which is applied to second amplifier element, and a second substantially identical difference circuit which comprises a comparator in which the output signal of the second amplifier element is compared with the input signal thereof to produce a correction signal which is applied to the first amplifier element; a desired signal to be amplified being applied to both amplifier elements. The two amplifier elements, which may be preceded by preamplifiers, take the form of power amplifiers. Because the distortion signals appear at the load as "common mode" signals, the overall distortion becomes substantially zero in the case of equal attentuation in the two difference circuits.

Abstract: An amplifier is disclosed which is capable of operation from 0 MHz to over 100 MHz with very low distortion over this entire range. Several inputs may be combined without affecting the gain of the amplifier. Several outputs may be combined without adding to the distortion products significantly. A pair of common-base symmetrically juxtaposed transistors drives a pair of symmetrical common-emitter transistors. An AC and DC feedback loop is provided along the line of symmetry. In addition, each symmetrical half of the set of four transistors has a DC feedback loop which balances current between stages of said half and inhibits overcurrent conditions in the transistors of that half.

Abstract: A current source in which the output current from an output amplifier stage (2) is controlled by an input signal, originating in a signal source (11), to an input amplifier stage (1) incorporates, additionally to a negative feedback path from the current input path of the output stage (2) to the input amplifier (1), monitoring means (5) in the signal input path to the output amplifier (2) and control means (4) in an input path to the input amplifier (1). Monitoring means (5) monitors the current flow in the input path to the output amplifier (2) and applies, via control means (4) a signal to the input amplifier (1) such that the dependence of the current flow in the current output path on the gain of the output stage (2) is reduced. A circuit is described, as well as an application to driving a telephone subscriber line and using two current sources working in push-pull mode.

Abstract: The output stage of a quasi-linear amplifier employs a p-channel and an n-channel FET with their sources at relatively positive and relatively negative operating voltage rails to drive a load from their drain-to-drain connection, so that despite their being enhancement types full rail-to-rail output voltage capability can be obtained without need for bootstrapping. Input signal voltage and direct-coupled feedback voltage are applied to the gate-to-gate connection of p-channel and n-channel source-followers with their respective sources direct-coupled to the gate of the p-channel FET in the output stage and to the gate of the n-channel FET in the output stage, respectively, and with their respective drains connected to the relatively positive operating voltage rail and to the relatively negative operating voltage rail, respectively, in a representative driver stage.

Abstract: An arrangement to provide feedback to amplifier systems incorporating an inductive laod. A low value error-sensing resistor is incorporated in conjunction with one or more transistors to provide a feedback correction signal to an amplifier which corrects for distortion caused by both the amplifier and the inductive load. A first embodiment providing a single-ended amplifier system incorporates an error-sensing resistor in series with a transistor, an inductive load and a bias resistor. A negative feedback error signal is provided to the amplifier from a point between the error-sensing resistor and the bias resistor. A second embodiment additionally includes a transformer to isolate the load. The third embodiment provides push-pull amplifier configurations. The third embodiment incorporates two complementary transistors to drive an inductive load. A pick-off arrangement including two capacitors and an error-sensing resistor provides negative feedback to the amplifier.

Abstract: The cut-off frequency of a transistor drops remarkably when the collector-emitter voltage of the transistor is driven into the quasi-saturation region of about 1 V. To prevent this problem, the collector-emitter voltage of the transistor is detected and compared with a predetermined reference voltage by comparison-limiting means. The comparison-limiting means limits the base current of the transistor and thus restricts the drop in the collector-emitter voltage. Limiting the voltage drop in this manner prevents the transistor from being driven into the quasi-saturation region. The reference voltage is set to the p-n junction voltage in the forward direction. Hence, the drop in the collector-emitter voltage is limited to a value near this reference voltage.

Abstract: A high power integrated circuit amplifier employs emitter ballasted NPN output transistors. One output transistor is driven by a PNP transistor to create a composite pair. Since the ballast resistor, in the composite pair, is effectively in the collector of a PNP equivalent transistor, the output stage creates substantial distortion. The output stage is driven by a conventional high gain capacitance compensated amplifier. By connecting an additional negative feedback capacitor between the emitter of the composite pair output transistor and the driver amplifier input, the distortion can be effectively compensated without resorting to power dissipative distortion reduction.

Abstract: A push-pull amplifier circuit comprises first and second output transistors whose emitters are commonly connected respectively through resistors to an output point, together with base biasing circuits connected between the bases of the first and second output transistors, to perform push-pull operation. The base biasing circuits comprise first and second current detecting elements for detecting the currents of the first and second output transistors, first and second variable bias generators controlled by the first and second current detecting element and reference bias generators. The operations of the first and second output transistors are effected in the active regions at all times.

Abstract: A highly efficient class-B current source audio amplifier with little heat generation having one amplifier half fixedly biased with the other amplifier half slave biased to the first. Each amplifier half contains a tandem chain of unmatched transistors. The first amplifier half has separate ambient and load temperature controls to substantially minimize distortion due to any change in the operating characteristics of the transistor chains and to substantially minimize the possibility of power transistor failures due to overheating.

Abstract: The disclosed amplifier includes first and second gain stages and first and second frequency compensating capacitors. The second gain stage has a first high impedance node coupled to the first gain stage, a second high impedance node, a first circuit coupled between the first and second high impedance nodes, a third high impedance node, and a second circuit coupled between the second and third high impedance nodes. The impedances at the first, second and third high impedance nodes are a function of frequency and the impedance at the second high impedance node is lower at any given frequency than the impedances at the first and third high impedance nodes. The first frequency compensating capacitor is coupled between the first and third nodes and the second frequency compensating capacitor is coupled between the third and second nodes.

Abstract: A power amplifier comprises: a complementary symmetry push-pull circuit formed with two complementary transistors mutually coupled at their emitters and having an operating point for Class-A mode operation; a floating power supply having a neutral terminal serving as the output terminal of the power amplifier, a positive and a negative terminal connected respectively to the collectors of the respective transistors; a bootstrapping circuit for driving the mutually coupled emitters in proportion to the potential at the output terminal; and a circuit for negative feedback of signal from the output terminal to the bases of the transistors.

Abstract: In a low-level audio preamplifier circuit having complementary connected PNP and NPN bipolar transistors cascode coupled to other complementary PNP and NPN bipolar transistors in receiving the audio input from a low-level transducer in which induced distortion from externally generated radio frequence energy is cancelled.

Abstract: A miniature guitar amplifier, having at least one very small (13/4 inch) speaker driven by complementary transistors connected in an emitter-follower push-pull arrangement, is made to sound very much like a large guitar amplifier having one or more large (12 inch) speakers by providing negative feedback to an operational amplifier that drives the power transistors. The operational amplifier has a differential input stage to provide a noninverting input terminal for the signal from a guitar pickup and an inverting input terminal for the feedback signal.

Abstract: A high voltage/high current circuitry includes a push-pull voltage amplification stage connected in tandem with a parallel connected push-pull current amplification stage. For the voltage amplification stage a pair of bipolar operational amplifiers are connected in parallel and operate in a push-pull manner. A pair of switching means are positioned at the output of each of the bipolar operational amplifiers while the outputs of the amplifiers are connected to the inputs through a current gain regulating means, an isolation means and a voltage divider means.

Abstract: A transistorized power amplifier includes a differential pair coupled to a push-pull driver. The latter provides an amplified signal to an output stage through a compound driver, which comprises a pair of complementary transistors. The collector of the input transistor of the compound driver is connected to the base of the other transistor in the compound driver.

Abstract: A complementary or quasi-complementary Class B transistor amplifier stage, the halves of which have their output circuits serially connected between relatively negative and relatively positive operating supply voltages to receive direct current and are operated in push-pull with each other for signal to supply a common load from the interconnection of their output circuits, has driver circuitry including a pair of field effect transistors operated in push-pull to supply respective halves of the Class B transistor amplifier. A p-channel field effect transistor with source electrode connected to the relatively positive operating supply voltage drives one half of the Class B transistor amplifier stage from its drain electrode, and an n-channel field effect transistor with source electrode connected to the relatively negative operating supply voltage drives the other half of the Class B transistor amplifier stage.

Abstract: In a low level audio preamplifier circuit having complementary connected PNP and NPN bipolar transistors for receiving the audio input from a low level transducer such as a tape head, in which induced distortion from externally generated radio frequency energy is cancelled with minimal loss of audio fidelity.

Abstract: A phase compensator circuit for a multistage amplifier circuit is made up of two capacitors which are connected between input and output terminals of a first amplifier circuit, and a resistor which is connected between a common juncture of the two capacitors and an output terminal of a second amplifier circuit succeeding to the first amplifier circuit. The phase compensation is carried out substantially by the two capacitors in a high frequency region, and by the resistor and the capacitor intervening between the input terminal of the first amplifier circuit and the output terminal of the second amplifier circuit in a low frequency region.

Abstract: A class B push-pull transistor power amplifier is disclosed having two amplification branches each of which is internally compensated in the signal processing/voltage amplifying section thereof for the effects of temperature on the transistors contained therein by allowing the outputs of the respective branches to drift apart slightly with temperature and using a portion of the quiesent current thus produced to alter the bias on the inputs of the respective branches.

Abstract: A complementary transistor output circuit and method incorporates an optical coupler including a light emitting diode and a phototransistor connected between the base electrodes of a complementary pair of output transistors including a PNP transistor and an NPN transistor. The emitter of each of the output transistors is connected to an output of the output circuit. The base electrodes of the PNP output transistor and the NPN output transistor are connected, respectively, to first and second current source circuits. The collector electrode of the NPN output transistor is coupled by means of a first feedback circuit including a first resistor and a PNP transistor to the anode of a light emitting diode. The collector electrode of the PNP output transistor is coupled by means of a second feedback circuit to include a second resistor and an NPN transistor to the cathode of the light emitting diode.

Abstract: A wide bandwidth video amplifier suitable for driving a kinescope of a television receiver exhibits suppressed radio frequency (RF) harmonic radiation. The amplifier includes a transistor having a nonlinear conduction characteristic in a region of low current conduction. An input circuit including a source of video signals is coupled to a base electrode of the transistor, and output signals are provided from a collector output circuit of the transistor. Degenerative direct current feedback is provided from the output circuit to the input circuit. Undesired RF harmonics produced by dynamic operation of the transistor in a region of low current conduction is suppressed in a first instance by a nonlinear conduction device (e.g., a forward biased diode) arranged to provide degenerative emitter feedback for the transistor during low current conduction. Harmonic radiation is suppressed in a second instance by a low pass filter interposed between the input circuit and the base electrode of the transistor.

Abstract: An amplifier circuit suitable for use as a video amplifier in a color television circuit for driving the variable impedance load provided by a color television picture tube, in which the load impedance of the amplifier element of the circuit is also made variable. This is achieved, in one embodiment by using as the output stage of the amplifier two transistors with a complementary symmetrical configuration so that one is always substantially cut-off while the other conducts. In another embodiment a transistor in common collector configuration acts as the amplifier element and its emitter from which the output of the amplifier is taken is connected by a diode to the collector of a transistor which feeds the base of the common collector transistor.

Abstract: A broad-band radio-frequency amplifier is characterized by a gain which may be adjusted over a relatively large range, and which remains stable over the range of gain adjustments. The amplifier includes first and second transistor pairs each arranged in a cascode connection; a feedback capacitor connected across the output and input of each cascode pair; and inductance serially included at selected circuit points. Also disclosed is a hybrid circuit for efficiently implementing the amplifier.