Abstract: In an output amplifier (20) which is operated in class AB with the aid of quiescent-current means (40, 50) and which comprises first output-transistor configuration (T.sub.10 -T.sub.14) and a second output-transistor configuration (T.sub.15 -T.sub.17) with output transistors (T.sub.14, T.sub.17) of the same conductivity type, the drive signals for these output-transistor configurations are derived from the output signal (V.sub.i) of the input amplifier (10) by means of a single voltage-to-current converter (30). In the case of a positive drive of the first output transistor configuration (T.sub.10 -T.sub.14) this converter (30), together with the first output-transistor configuration (T.sub.10 -T.sub.14) and a load (R.sub.L) connected to the output (5) of the output amplifier (20), constitutes an amplifier configuration with full negative feedback, while in the case of a positive drive of the second output transistor configuration (T.sub.15 -T.sub.

Abstract: This disclosure relates to a multi-channel power amplifier utilizing Darlington pairs as the inputs of a cascode amplifier. The Darlington pair inputs may implement an added grounded resistor to the emitter of the pre-driver transistor in each Darlington pair. The added resistance allows for individual adjustment of the dc current in the pre-driver transistor of each Darlington pair, as well as an additional discharge path for the charges stored on the base of the driver transistor in each pair during a decreasing current state.

Abstract: Apparatus and method for driving a non-centertapped load such as a loudspeaker from a low voltage supply such as a single dry cell, with increased efficiency. A push-pull signal having similar polarity voltage excursions is applied to opposite terminals of the load. Alternate individual terminals of the load which are opposite to the terminals to which the non-idle phases of the push-pull signal are alternately applied are connected to a common terminal via a pair of transistors. The pair of transistors are driven by an amplified representation of the push-pull input signal. Since pulse signals are not used to drive the pair of transistors, capacitors need not be used to eliminate switching transients which would otherwise appear, and increased efficiency results.

Abstract: The invention relates to a high frequency, high mechanical energy output apparatus comprising a transducer, a filter circuit, and a driving circuit. The transducer and the filter circuit are serially coupled together, and the transducer operates at its fundamental frequency of oscillatory motion. The driving circuit serves to drive the transducer at its fundamental frequency and comprises first and second active devices, wherein each active device has an output circuit and a control circuit. Each of the active devices are cooperatively connected together and are responsive to control signals for producing an alternating output signal. There is also provided means coupling the output circuits of the active devices to the transducer so that an alternating series current signal is applied serially through the transducer.

Abstract: An operational amplifier includes an input stage, an output stage including first, second and third NPN output transistors, and an intermediate stage. The first NPN output transistor sources load current to an output terminal while the second and third output transistors sink load current therefrom. The output of the intermediate stage is coupled to the base of the third NPN transistor and, via a resistor, to the base of the second NPN transistor. A first Miller capacitor is coupled between the input of the intermediate stage and the amplifier's output terminal, and a second Miller capacitor is coupled between the base of the second NPN transistor and the output terminal.

Abstract: A feedback amplifier is provided with a voltage-controlled compensation circuit which varies the effective feedback capacitance by controlling a proportional amount of feedback current returned via the capacitor to the amplifier summing node. The proportionality and current steering of the feedback current is effected by a multiplier circuit, the bias of which is controlled by an adjustable DC voltage. Several feedback amplifier configurations are shown herein, exemplifying the versatility of the compensation circuit of the present invention.

Abstract: A distortion-free amplifier in accordance with the present invention includes an input amplifier, an output amplifier and method, and a cooperative combination of negative and positive feedback loops that remove substantially all distortion and error in the amplified output. Negative feedback loops are provided around the output amplifier and the input/output amplifier combination to provide degenerative error reduction. The negative feedback loop around the output stage provides a portion of the output to a voltage node at which the error component of the output signal is inversely superposed on the inverted signal to be amplified. This highly "visible" (inverse, intra-loop) error component is utilized as positive feedback to provide a regeneratively enhanced error pre-correction of the signal in the input amplifier. The pre-correction can be precisely controlled to effect virtually complete serial cancellation of the to-be-introduced error as the signal is propagated through the amplifier.

Abstract: A circuit arrangement incorporated in a class AB amplifier for controlling the quiescent current through the transistors (T1, T2) incorporated therein so that the load current (I.sub.L) is zero when the input voltage (I.sub.IN) to the amplifier is zero. The arrangement comprises two feedback loops, each connected to the base circuits of both amplifier transistors. One feedback loop comprises a sensing resistor (R1) connected to the load (Z), an adder (S1) and an amplifier element (A1) with high gain and input impedance. The second feedback loop comprises a sensing resistor in the main current flow of the second transistor (T2), an adder (S2) and an amplifier element (A2) of the same kind as the first one (A1). The degree of feedback in the second loop is suitably selected greater than that of the first loop to achieve a greater control range for the amplifier.

Abstract: The invention provides an improved class-B push-pull output stage comprising a first and a second output transistor of a first conductivity type, which stage is provided with a control loop for driving the second transistor in phase opposition as a function of the drive of the first transistor. Said control loop is adapted so that a stable quiescent-current setting is obtained and that the effect of poor high-frequency properties of a third transistor of a conductivity type opposite to the first conductivity type, which transistor is necessarily included in the control loop, is eliminated, so that a wide frequency range is obtained.

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: A quasi-linear amplifier, wherein each of first and second current dividers maintains a constant ratio between drive currents to respective output transistor means and dummy output transistor means, uses regulation of the quiescent drive currents to the dummy output transistors to establish the quiescent drive currents to the output transistors. The quiescent drive currents to the output transistors are maintained at levels conditioning these transistors for Class AB amplification of signal currents.

Abstract: A power amplifier circuit is mainly composed of an amplifier including an input transistor, a driving transistor and a power amplifying transistor. This power amplifying transistor is connected at its output end to an output transformer the secondary winding of which is connected to a first adjusting means for adjusting an output impedance of the power amplifying transistor. A second adjusting means, which is interlocked with the first adjusting means, is provided on the current path of the driving transistor to adjust the value of an emitter resistance of the driving transistor, and the biasing voltage of the power amplifying transistor is obtained from the current path of the driving transistor, thus the power consumption of this circuit being reduced by the adjustment of the first and second adjusting means.

Abstract: A feedback transistor, whose base and emitter are connected respectively to the base and emitter of a common emitter output transistor, conducts a collector current which is directly proportional to the output current. The collector current of the feedback transistor is fed back to the input of an amplifier which drives the output transistor. The resulting negative feedback controls overall gain, reduces distortion, and controls the quiescent current of the output transistor. Application of this linear current feedback technique to both class A and class B amplifiers is disclosed.

Abstract: The collectors of a pair of transistors operated quasi-linearly in push-pull are coupled to their load by an autotransformer winding, center-tapped to receive operating potential. The configuration simulates a full-bridge amplifier with operating potential twice as large, insofar as maximum output power capability is concerned.

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 low level, low power, direct coupled integrated class B amplifier having a dual channel three stage preamplifier and a pair of output transistors, one for each channel. In each channel, a DC negative feedback loop connects the collector of the last stage preamplifier transistor to the base of the first stage preamplifier transistor to regulate the DC levels, and a resistive AC negative feedback loop connects the output transistor collector to the first preamplifier transistor collector to reduce the gain dependence of the channel on the current through the output transistor, thus enabling very low idle currents for the output transistors and also providing low distortion output. The resistor in each AC feedback loop is a floating tub resistor to enable it to be taken more than 0.6 volts above the battery voltage. Common mode rejection is provided for at least two of the three preamplifier transistors of each channel.