Showing papers on "Cascade amplifier published in 1980"

High-efficiency low-distortion amplifier

Abstract: An amplifier system comprising at least two tracking switching regulators or a dual-output regulator, which regulators vary the voltage across the output stage at the signal or its envelope rate.

Hearing aid amplifier

Abstract: A general purpose hearing aid amplifier is programmably adaptable to the prescription requirements of the hearing impaired. The hearing aid amplifier comprises a bank of bandpass-restricted channels, each channel having a voltage-controlled input amplifier, a voltage-controlled compressor, and a voltage-controlled output amplifier for shaping the gain, attack and delay characteristics of the selected channel. The bank is fed through a fixed high-pass filter from a microphone input, and a mixed output drives a power amplifier for an output transducer such as a hearing aid speaker. The amplifier is programmably adaptable through the use of a monolithic programmable switch array using, for example, semiconductor fuseable link technology to preset digital-to-analog converters voltage controllable levels of the amplifiers and compressors of each channel according to a digital control input. The monolithic switch array is coupled to the programmable amplifiers through digital to analog converters which establish the programming voltages for the amplifiers and compressors. The monolithic switch array digital to analog converters may be constructed on the same monolithic semiconductor chip.

Low impedance electrostatic detector

Abstract: An electrostatic detector comprising a detector electrode sensitive to electrostatic quantities such as fields, voltages, charges and the like, means for varying the capacitive coupling between the electrode and an electrostatic quantity to which the electrode is exposed, and an operational amplifier having an output and a pair of inputs, one of which is operatively associated with the amplifier summing node. A resistive feedback path is defined between the amplifier output and the summing node, the detector electrode is connected to the one amplifier input so that the detector electrode is operated directly into the amplifier summing node, and the other amplifier input is connected to an electrical reference, such as ground. As a result, the detector electrode is held at virtual ground and the amplifier is operated as a current to voltage converter to cause an output voltage to be generated equal to the product of the input current and the resistance of the feedback path. The detector can be employed in a non-contacting electrostatic voltmeter for making surface voltage measurements and which employs any one of several capacitance modulation schemes.

Transceiver for full-duplex transmission of digital signals over a common line

Abstract: A transceiver inserted between a signal source and a two-wire or one-wire line, designed to transmit balanced or unbalanced digital signals to a remote station at the opposite end of the line while receiving similar signals from the latter station, comprises a first and a second amplifier with inputs connected to the line at a proximal and a distal end of a line-terminating impedance, respectively. Each amplifier has an inverting output connected to a noninverting output of the other amplifier, the two nodes formed between the interconnected outputs being connected to respective inputs of a differential third amplifier feeding a signal receiver. The gain of the first amplifier is half that of the second amplifier whereby the locally generated signals are suppressed in the output of the third amplifier. The several amplifiers are realized in integrated circuitry and may be provided with switches for selective changeover between a balanced and an unbalanced mode of operation.

High efficiency, light weight audio amplifier and power supply

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. In another embodiment, a stereo amplifier constructed in accordance with the present invention contains a network (1602) for inverting the audio signals received by a first amplifier input channel (1600). The inverted signals are thereafter processed in out-of-phase relationship to the signals in the second amplifier input channel (1500) to more efficiently utilize the power supply. In yet another embodiment, the power supply (1710) itself is constructed with a number of fault detecting circuits which sense fault conditions in either the power supply or the amplifier and shut the power off accordingly.

Power combiner arrangement for microwave amplifiers

Abstract: The present invention relates to an N-way non-hybrid power combiner arrangement for microwave amplifiers. In operation, sensing means (19 1 , 19 2 , . . . , 19 N ) are coupled in a one-to-one relationship with the individual amplifiers (12 1 , 12 2 , . . . , 12 N ) to monitor amplifier performance and sense amplifier failure. In one embodiment of the present invention, shorting devices (20 1 , 20 2 , . . . , 20 N ) are disposed adjacent to the outputs of the individual amplifiers and coupled to the associated sensing means in a one-to-one relationship. In an alternative embodiment, open-circuiting devices (30 1 , 30 2 , . . . , 30 N ) are disposed at a predetermined distance from the amplifier outputs along the transmission lines (24 1 , 24 2 , . . . , 24 N ) and coupled to their respective sensing means. Upon identifying amplifier failure, the sensing means coupled to that particular amplifier activates either its associated short-circuiting or open-circuiting device, which in turn uncouples the failed amplifier and the transmission line associated therewith.

Transimpedance oscillator having high gain amplifier

Abstract: A transimpedance amplifier is connected in a positive regenerative loop with a crystal resonator. The transimpedance amplifier includes a high gain amplifier with a parallel resistor and capacitor thereacross. A virtual ground is created at the node between the resonator and the amplifier input thereby eliminating circuit sensitivity to inherent capacitive changes between the resonator and true ground. Components are chosen to maintain oscillations at series resonance and achieve insensitivity to changes in the motional resistance of the resonator.

Sense amplifier for CCD memory

Abstract: A sense amplifier for use with a charge coupled device in which capacitive coupled charge is employed with a flip-flop circuit to accelerate sense and readout. Operation of the amplifier is effected with two external clocks and two internally generated clocks.

Linear high gain sampling amplifier

Abstract: A signal sampling circuit comprising a switch network coupled to a transconductance amplifier for providing output currents proportional to input voltage, an input clamp network, and a charge storage device is disclosed. The amplifier signal input is clamped to a reference potential via a negative current feedback path when the switch occupies a first position during nonsampling, clamping intervals. During subsequent sampling intervals, the switch occupies a second position for decoupling the feedback path and coupling the amplifier output to the storage device, so that the storage device then develops a sample of amplifier output signals, referenced to the clamping potential, as a function of amplifier output currents.

Sample and hold circuit particularly for small signals

Abstract: A signal sampling circuit comprising a signal inverting amplifier with a gain greater than unity, an input clamp network including a feedback switch, and an output sampling network including a charge storage device and a sampling switch is disclosed. The amplifier input to which signals to be sampled are applied is clamped to the amplifier output potential via the feedback switch during non-sampling, clamping intervals. During subsequent sampling intervals, the feedback switch is disabled and the sampling switch is enabled to couple the amplifier output to the storage device, so that the storage device develops a voltage sample of amplifier output signals referenced to the clamping potential.

Cmos operational amplifier with improved frequency compensation

Abstract: An operational amplifier circuit comprised of complementary MOS transistors (72, 80) and having a bias section (14), a differential amplifier section (12), a level shift stage (16), and an output stage (18), provides for frequency compensation using two capacitors. One capacitor (88), connected between the differential amplifier section and the output stage through a CMOS transmission gate (96, 98) that functions as a resistor, acts as the dominant pole of the transfer function. A second capacitor (78) between the amplifier section output node (50) and a level shift transistor (60), functions to remove the secondary poles in the transfer function and cause the dominant pole to occur at a higher frequency.

Method of harmonizing the impedances of an audio amplifier and loudspeaker interconnected therewith

Abstract: A method of harmonizing the impedances of an audio amplifier and a loudspeaker interconnected therewith, the audio amplifier including a line amplifier and a positive feedback circuit for compensating for the counter electromotive force of the loudspeaker. A voice coil of the loudspeaker is mechanically driven for generating an electric signal at input terminals of the loudspeaker. Then, the amplification degree of the line amplifier or the positive feedback circuit is adjusted to reduce the signal voltage between the input terminals of the loudespeaker to a minimum, during the circulation of the generated signal through the positive feedback circuit and the line amplifier.

Low sensitivity switched-capacitor ladder filter using monolithic MOS chip

Abstract: A switched-capacitor circuit (50) for passing an audio frequency over a predetermined range of frequencies fabricated on a monolithic semiconductor substrate is provided. The switched-capacitor filter (50) includes a first amplifier (60) and a second amplifier (90). A first integrator capacitor (66) is interconnected to the first amplifier (60). A second integrator capacitor (96) is interconnected to the first amplifier (90). A first input switched-capacitor (82) is interconnected between the first amplifier (60) and the second amplifier (90), such that the first input switched-capacitor (82) samples and holds the output of the second amplifier (90) during a first clock phase thereby isolating the output of the second amplifier (90) from the input of the first amplifier (60). During a second clock phase the first input switched-capacitor (82) applies the output of the second amplifier (90) to the first integrator capacitor (66). A second input switched-capacitor (112) is provided and is interconnected between the output of the first amplifier (60) and the input of the second amplifier (90), such that during the second clock phase the second input switched-capacitor (112) applies the output of the first amplifier (60) to the second integrator capacitor (96). The switched-capacitor circuit (50) functions such that effectively zero phase shift is introduced into the signal being processed by the switched-capacitor circuit (50).

Cardiac amplifier system with low transient fast switching

Abstract: A cardiac amplifier system with several patient electrodes includes an amplifier with a capacitor coupled input and a switch for coupling different ones of the patient electrodes to the amplifier. A circuit including a time delay, a pair of sequentially operated controlled conduction devices and a resistive network shunts the amplifier input and charges the coupling capacitors in a controlled fashion when the selector switch is operated to prevent switching transients from being applied to the amplifier.

Audio-frequency amplifying device

Abstract: The audio-frequency amplifying device comprises a first class B amplifier, a second class B amplifier, switching means controlled by a control sub-assembly and transmission means applying a signal to the input of the second amplifier. The load is connected to the first amplifier, and to the switching means connecting it either to the output of the second amplifier or to a zero potential middle point.

Bridge amplifiers employing complementary field-effect transistors

Abstract: A bridge amplifier is provided wherein one end of a load device is driven by a first amplifier and the other end of the load device is driven by a second amplifier. The second amplifier is an inverting amplifier comprising P and N-channel field-effect transistors, having complementary symmetry conduction characteristics. The input to the second amplifier is directly coupled to the output of the first amplifier.

A Monolithic GaAs I.F. Amplifier for Integrated Receiver Applications

Abstract: A monolithic GaAs integrated amplifier has been constructed for the 500 to 1000 MHz intermediate frequency band. The amplifier provides 8.0 /spl plusmn/ 1.5 dB gain across the band. The output of the amplifier utilizes a source follower configuration to obtain a favorably low output VSWR of less than 1.5:1 (return loss >15 dB). All bias lines with integral bypass capacitors are contained on the chip and this amplifier is suitable for further integration as a building block of a monolithically integrated receiver front end.

Amplifier arrangement with parallel-operated amplifier sections

Abstract: By adding the difference between output and input of the one amplifier section to the output signal by means of a subsequent amplifier section a ring of amplifier sections can be formed which compensate for each other's distortion.

Monolithically integrable semiconductor circuit with an amplifier controlled by a photo diode

Abstract: Monolithically integrable semiconductor circuit with an amplifier controlled by a photo diode, including a differential amplifier having inverting and noninverting inputs and outputs and a photo diode having a first and a second lead, the first lead of the photo diode being connected in the blocking direction to the inverting input of the differential amplifier, and the noninverting input of the differential amplifier being connected to a reference potential, a coupling resistor connected between the inverting and noninverting inputs of the differential amplifier, a filter circuit and a transistor amplifier being connected in a feedback branch between the noninverting output and the inverting input of the differential amplifier, and the inverting output of the differential amplifier and the second lead of the photo diode being connected to ground.

Amplifier comprising a first and a second amplifier element

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. The power amplifiers may be provided with a voltage output as well as a current output.

Feedforward wideband amplifier

Abstract: The performance of a wide band feedforward power amplifier circuit is enhanced when a phase intercept distortion compensation circuit is used to provide phase and amplitude matching between the signal amplifier and the feedforward path.

Low-Noise Wide-Band Amplifier System for Stochastic Beam Cooling Experiments

Abstract: A new low-noise wide-band power amplifier system has been developed for stochastic beam cooling experiments. The system incorporates a low-noise preamplifier with a noise figure of 1.9 dB over a bandwidth range of 20 to 300 MHz, wide-band driver and buffer stages, a frequency characteristics shaping network, a remotely controlled wide-band attenuator with 0.1 dB resolution, a remotely controlled high resolution adjustable delay line, and a wide-band solid-state output power amplifier. The amplifier system has a maximum voltage gain of 140 dB over a bandwidth from 1.5 to 310 MHz, a signal group delay of 55.5 ns, and a c. w. output power level of 75 W. Particular attention was paid to minimizing the signal propagation time delay of the amplifier system, the propagation time delay change as a function of the system gain, and harmonic and intermodulation distortions. Using a new wide-band electron bombarded semiconductor output amplifier, the system will have a bandwidth from 30 to 400 MHz, a signal group delay of 37 ns and an output power of 100 W.

High frequency pulse amplifier

Abstract: A high frequency amplifier comprises an amplifier stage connected in a grounded base configuration, or a plurality of such amplifier stages connected in tandem, for amplifying high frequency pulses. In order to produce high frequency pulses wherein the output power has a required pulse shape, at the emitter side of each amplifier stage a constant current source is connected which is controlled by a pulse generator which is operable to provide a current having a pulse shape which corresponds to the pulse shape which is the same as the input high frequency pulses.

Novel two-o.a. three-resistor variable phase inverting amplifier

Abstract: A new active phase-compensated inverting amplifier is proposed. The amplifier circuit employs two o.a.s and three resistors and has an infinite input impedance. The proposed amplifier is also suitable for phase correction in two-integrator loop filters.

Automatic gain control arrangement useful in an FM radio receiver

Abstract: In an FM receiver including a plurality of cascaded amplifier stages for successively amplifying an IF signal to form a pulse signal which is demodulated to derive an audio signal, an auxiliary amplifier section beside the cascade is provided to amplify a signal developed at an intermediate point in the cascade to form a signal from which a control signal for controlling the gain of an RF amplifier. The auxiliary amplifier section includes a first linear amplifier including degenerative signal feedback followed in cascade by a second linear amplifier including a gain control arrangement. The latter is responsive to a logarithmic gain control signal generated by a logarithmic amplifier in response to the output signal of a peak detector following the auxiliary amplifier. The control signal has a relatively wide control range, e.g., 10 to 500 microvolts of RF input signal, suitable for controlling the gain of an RF stage.

Switched-capacity amplifier, switched-capacity filter and charge-transfer filter comprising such an amplifier

Abstract: A switched-capacity amplifier formed from integrated capacities has undesirable parasitic capacities that are large and variable on only one terminal of each of the capacities. A voltage-follower stage is connected to this terminal of each of the capacities (except those capacities which are grounded) to offset the parasitic capacity. The amplifier is also connected in a switched-capacity filter and a charge-transfer filter.

Phase compensated controlled oscillator

Abstract: RCA 72,790 Abstract of the Disclosure A controlled oscillator comprises an amplifier including an active device, a filter network arranged in a feedback loop of the amplifier for providing regenerative feedback to sustain oscillation of the amplifier, and a source of control signals. Output oscillatory signals from the amplifier and output control signals from the control source are summed by a combining network to produce a resultant controlled signal, which is coupled to the filter network. Parasitic capacitances associated with output terminals of the amplifier and control source impart an unwanted phase shift to the controlled signal. A compensation signal derived from the oscillator is supplied to the combining network with a magnitude and phase to offset the unwanted phase shift, to thereby produce a phase compensated resultant controlled signal.

Device for monitoring an amplifier stage

Abstract: 1 Monitoring amplifier circuit for a voltage measuring device for multiphase high voltage installations, with a capacitive voltage divider (1) transforming a primary high voltage each into a lower input voltage, amplifier lines (2, 3, 4) for the input voltages provided by the voltage divider (1) and each comprising a preamplifier (7) and a final amplifier (9), devices for montoring the input and output voltages of each amplifier line (2, 3, 4), and devices for the remplacement thereof, characterized in that a) an identical replacement amplifier line (6) connectable instead of each amplifier line (2, 3, 4) is provided, b) the monitoring devices comprise an evaluation circuit (29) receiving the input voltage and the output voltage of each amplifier line (2, 3, 4), and a voltage comparison (13) embodies as a part of a microcomputer (23), c) voltage comparison circuit (13) is laid out, in excess of the comparison of the actual values of the input voltage and the output voltage, for comparison of the actual comparison value obtained thereby with a desired value and for output of a logical signal on deviation of the actual comparison value from the desired value, and d) a switching device (17) for connecting the replacement amplifier line (6) instead of the failed amplifier line (2, 3, 4), actuated in response to the logical signalm of the voltage comparison circuit (13) is coordinated to the microcomputer (23) detecting the fautly amplifier line (2, 3, 4)

A Novel Active Phase Compensated Inverting Amplifier

Abstract: Ü b e r s i c h t : Es wird eine neue aktive Phasenkompensation für invertierende Verstärker angegeben. Die vorgeschlagene Schaltung enthält zwei Operationsverstärker und vier Widerstände. Es werden drei Spezialfälle diskutiert; die Ergebnisse sind tabellarisch zusammengefaßt. Um Phasenund Amplitudenfehler klein zu halten und um eine große Bandbreite zu erreichen, ist lediglich ein zusätzlicher Operationsverstärker zur Phasenkompensation eines invertierenden Summierverstärkers notwendig. Dieser Breitbandverstärker zeichnet sich damit durch eine besonders wirtschaftliche Phasenkompensation aus. Für d ie D o k u m e n t a t i o n : Breitbandverstärker / Operationsverstärker / Phasenkompensation 1. I n t r o d u c t i o n The inverting weighted summer which includes the inverting voltage controlled voltage source (VCVS) as a special case is a very useful building block in active AC networks. It is well known that the performance of the inverting VCVS depends on the realizable gain and the used opamp. Let the open loop gain of the op-amp be represented by the one pole model