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Showing papers on "RF power amplifier published in 1980"


Journal ArticleDOI
TL;DR: In this article, an ultrawide-band amplifier was developed that covers the frequency range from 350 MHz to 14 GHz with a minimum gain of 4 dB at an output power of 13 dBm.
Abstract: An ultrawide-band amplifier module has been developed that covers the frequency range from 350 MHz to 14 GHz. A minimum gain of 4 dB was obtained across this 40:1 bandwidth at an output power of 13 dBm. The amplifier makes use of negative and positive feedback and incorporates a GaAs MESFET that was developed with special emphasis on low parasitics. The transistor has the gate dimensions 800 by 1 mu m. The technology and RF performance of the GaAs MESFET are discussed, as are the design considerations and performance of the single-ended feed-back amplifier module.

95 citations


Journal ArticleDOI
TL;DR: In this paper, an extensive study has been performed on a dye amplifier pumped by copper vapor lasers, which utilizes a transverse pumping configuration in which the dye flow, pump beam, and dye extraction beam are mutually orthogonal.
Abstract: An extensive study has been performed on a dye amplifier pumped by copper vapor lasers. The amplifier utilizes a transverse pumping configuration in which the dye flow, pump beam, and dye extraction beam are mutually orthogonal. The operating characteristics of the amplifier have been studied using four dye-solvent systems which span the wavelength range continuously from 560 to 690 nm. Optimum conversion efficiencies of 18-30 percent at output powers of 0.41-0.76 W have been measured from the four dyes at a 6 kHz pulse repetition rate. The efficiencies and output powers were limited only by the available copper laser pump power. Analytic expressions have been obtained for the amplifier power gain and efficiency using a rate equation treatment of the system dynamics. Excellent agreement is obtained between the predicted and measured amplifier gain characteristics for rhodamine 6G.

76 citations


Patent
22 Dec 1980
TL;DR: In this article, a radio transmitter has an output power control circuit including a power amplifier, a directional coupler coupled to the power amplifier and a generator of a difference voltage between the output voltage of the detector means and a reference voltage.
Abstract: A radio transmitter has an output power control circuit including a power amplifier, a directional coupler coupled to the power amplifier, a detector of the forward power of the directional coupler, a generator of a difference voltage between the output voltage of the detector means and a reference voltage. A power regulator varys the output power of the power amplifier in response to the output of the difference voltage. The power applied from the power amplifier through the directional coupler to the detector is controlled by a control signal. The control circuit electrically varies the coupling coefficient of the directional coupler for attenuating the power applied from the directional coupler to the detector means to extend the controllable range of the transmitter output power.

59 citations


Patent
07 May 1980
TL;DR: In this paper, a multi-channel audio power amplifier is arranged to amplify, by an analog amplifying circuit, high frequency range components of an audio signal and to amplify low frequency range component of said signal by a class D amplifier, to enhance the power efficiency of the amplifier.
Abstract: A multi-channel audio power amplifier is arranged to amplify, by an analog amplifying circuit, high frequency range components of an audio signal and to amplify low frequency range components of said signal by a class D amplifying circuit, to thereby enhance the power efficiency of the amplifier. The carrier frequency of the class D amplifying circuit is set lower than that employed conventionally, to eliminate spurious radiation of the carrier signal.

52 citations


Patent
Roger E. Wolf1
08 May 1980
TL;DR: In this article, an offset voltage generator is coupled to an audio-frequency filter by a diode, and the voltage at the filter is maintained at the offset voltage while current flows in the offloading voltage generator and the inductors lose energy.
Abstract: An AM transmitter includes an RF signal generator and a switching-type RF signal amplifier. The RF amplifier output depends upon the energizing voltage applied thereacross, so it acts as a modulator. The energizing voltage is produced by a high-power audio amplifier which includes a pulse-width modulator driving a high-power audio switch. The switch terminals are coupled in series with an audio-frequency filter, energizing terminals of the RF amplifier and a source of direct energizing potential, for varying the voltage across the RF amplifier at an audio rate in response to the duty cycle of the width-modulated pulses for audio modulating the RF carrier. In order to reduce modulation distortion at low duty cycles resulting from the finite turn-on and turn-off time of the audio switch, an offset voltage generator is coupled to the filter by a diode. Energy stored in inductive components of the filter cause a voltage pulse during each turn-off of the audio switch. The voltage pulse is coupled to the offset voltage generator by the diode, and the voltage at the filter is maintained at the offset voltage while current flows in the offset voltage generator and the inductors lose energy. The offset generator includes a capacitor for storing energy resulting from the current flow in the inductor. A DC to AC inverter is coupled to the capacitor and generates alternating voltage. The AC is rectified and a pulsating direct current is coupled to the energizing source for recovering the energy in the inductive pulse.

49 citations


Journal ArticleDOI
TL;DR: In this paper, two schemes are discussed that improve the graceful-degradation performance of hybrid power dividers/combiners when one or more of the amplifiers fails, by replacing each failed amplifier by an equal-delay "through" connection and by using a resistor-free combiner.
Abstract: The standard method of employing n-way hybrid power divider/combiner to combine n amplifiers offers some sort of graceful-degradation performance when one or more of the amplifiers fail. Two schemes are discussed that improve that performance significantly. The first, which was proposed previously, involves replacing each failed amplifier by an equal-delay "through" connection. The second involves using a resistor-free combiner, and seperating each failed amplifier from the combiner by an appropriately placed short or open circuit.

38 citations


Journal ArticleDOI
01 Jun 1980
TL;DR: In this paper, a class-D voltage-switching tuned power amplifier is presented, in which complementary pair transistors are used and bases of the transistors can be coupled by a capacitor.
Abstract: Class-D voltage-switching tuned power amplifier circuits are presented, in which complementary pair transistors are used and bases of the transistors are coupled by a capacitor. These circuits have several advantages over previous circuits. They do not require a drive transformer and both transistors can be mounted on one heat sink.

30 citations


Journal ArticleDOI
TL;DR: In this article, the effects of discharge tube size and pulsing of the applied RF power are also considered and a comparison between RF and microwave excitation is made between inductively coupled radio-frequency (RF) plasmas excited in a series of inert gases.
Abstract: The vacuum ultraviolet (UV) emission from inductively coupled radio-frequency (RF) plasmas excited in a series of inert gases has been studied as a function of the pressure and applied power of the system. The effects of discharge tube size and pulsing of the applied RF power are also considered and a comparison is made between RF and microwave excitation.

30 citations


Patent
20 May 1980
TL;DR: In this paper, 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.
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.

27 citations


Journal ArticleDOI
TL;DR: In this article, the use of lower hybrid waves for current drive in steady-state tokamak power reactors was studied and the effect of decoupling of electron and ion temperatures was found to enhance the ratio of fusion power to dissipated power.
Abstract: The use of lower hybrid waves for current drive in steady-state tokamak power reactors is studied. Constraints imposed by RF wave propagation are considered. The effect of decoupling of electron and ion temperatures is studied and is found to enhance the ratio of fusion power to dissipated power. Tradeoffs for parameters of RF-driven steady-state reactors are determined. It is found that RF-driven steady-state current operation is especially suitable for high-field high-density reactor designs. For example, this study indicates that a tokamak power reactor characterized by a major radius of 6 m, a magnetic field on axis of 7.5 T, and a fusion power output of 2500 MW could be driven in steady-state operation with RF power level equal to 2.5% of the fusion power output.

27 citations



Patent
Adel A. M. Saleh1
06 Mar 1980
TL;DR: In this article, an N-way non-hybrid power combiner arrangement for microwave amplifiers is described. But the present approach is different from the one described in this paper.
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.

Patent
25 Jun 1980
TL;DR: In this article, a differential amplifier (24, 26, 10 and 12) having a feedback network (30, 34, 32, 36 and 38) for increasing common output without loss of gain is presented.
Abstract: A differential amplifier (24, 26, 10 and 12) having a feedback network (30, 34, 32, 36 and 38) for increasing common output without loss of gain. Also disclosed is a constant current source (60), and a level shifting network (48, 50, 52 and 54) for shifting the D.C. level of the output signal to a D.C. voltage substantially near that of second current source (44). An output stage (84, 86, 90, 92 and 94) provides low output impedance, low D.C. bias power consumption and high current drive capability.

Patent
17 Jan 1980
TL;DR: In this paper, a multistage radio frequency (RF) signal power amplifier is described that utilizes microstrip transmission line techniques for realizing essentially all of the matching circuitry for each stage of amplification.
Abstract: A multistage radio frequency (RF) signal power amplifier is described that utilizes microstrip transmission line techniques for realizing essentially all of the matching circuitry for each stage of amplification. The power amplifier includes a variable gain predriver, a driver amplifier and a pair of paralleled final amplifiers, all of which are intercoupled by microstrip coupling circuitry. A power detector senses the magnitude of the final amplifier output and provides a forward power signal having a magnitude proportional thereto. A power output regulator is responsive to the forward power signal for providing a drive signal for varying the gain of the predriver amplifier to maintain the magnitude of the final amplifier output at a preset magnitude. The RF signal power amplifier further includes spurious signal suppression circuitry coupled to the output of the driver amplifier and final amplifiers for suppressing spurious signals generated by regenerative modes of oscillation occurring therein. The spurious signal suppression circuitry includes a resistor coupled to a microstrip transmission line having a length such that the line is a relatively low impedance at the spurious signal frequencies and a high impedance at the RF signal frequency. Thus, the spurious signals are attenuated by the resistor, while the RF signal is essentially unaffected. The RF signal power amplifier embodying the present invention may be advantageously utilized in a radio communication system for amplifying signals to be transmitted by a base station radio.

Patent
14 Oct 1980
TL;DR: An amplifier with power supply switching is arranged so that the levels of the power supply voltages to be supplied to the amplifying elements of the output stage are switched over in accordance with the level and the rise time of a signal corresponding to an input signal of the amplifier as mentioned in this paper.
Abstract: An amplifier with power supply switching is arranged so that the levels of the power supply voltages to be supplied to the amplifying elements of the output stage are switched over in accordance with the level and the rise time of a signal corresponding to an input signal of the amplifier, thereby, to enhance the power efficiency and to prevent an increase of distortion, as well as to reduce switching noises which tend to occur during the switching of the power supply voltages.

Patent
08 Dec 1980
TL;DR: In this paper, a system including a frequency ramp generator feeding a transmitting power amplifier and antenna through a phase modulator and gain-controllable, transmitter driver stage is described, where instantaneous and long term frequency ramp phase and amplitude variations are substantially cancelled out so that the power amplified output is an accurate replica of the originally generated frequency ramp.
Abstract: A system including a frequency ramp generator feeding a transmitting power amplifier and antenna through a phase modulator and gain-controllable, transmitter driver stage. The frequency ramp generated is sampled out through a wide band delay-line feeding a phase comparator, the other comparison input to the phase comparator being provided by a sampling probe at the transmitting power amplifier output. The phase comparator output is used as a phase correction signal applied to the phase modulator and an amplitude modulation detector also responsive to the signal on the transmitting power amplifier output provides a feedback signal controlling the gain of the transmitter driver on a high bandwidth basis. Accordingly, instantaneous and long term frequency ramp phase and amplitude variations are substantially cancelled out so that the power amplified output is an accurate replica of the originally generated frequency ramp.

Patent
14 Apr 1980
TL;DR: In this article, a modular amplifier comprising a plurality of modules receives a signal to be amplified and provides an amplified signal through power divider and power combiner circuits which are mirror images of each other.
Abstract: A modular amplifier comprising a plurality of modules receives a signal to be amplified and provides an amplified signal through power divider and power combiner circuits which are mirror images of each other. In particular, 2-way Wilkinson hybrid circuits are combined to deliver the input signal by providing a divided signal to each of the amplifier modules. The output of each of the modules is combined by 2-way Wilkinson hybrid circuits to provide the amplified signal output. In order to provide discrete power reduction switching from a full power condition to a reduced power condition, at least one of the inputs to a module is connected to a quarter-wave stub which is selectively grounded and open-circuited to reflect respectively an open circuit and a short circuit condition. In this way, each amplifier module performs similarly in the reduced power output condition as well as in the full power output condition.

Patent
Antonio Pagnamenta1
17 Jan 1980
TL;DR: In this paper, a plurality of series coupled microstrip transmission lines of different characteristic impedances for matching a radio frequency (RF) signal power amplifier to a predetermined output impedance, such as, for example, 50 ohms, are described.
Abstract: Impedance matching circuitry is described that utilizes a plurality of series coupled microstrip transmission lines of different characteristic impedances for matching a radio frequency (RF) signal power amplifier to a predetermined output impedance, such as, for example, 50 ohms. Each of the microstrip transmission lines are successively coupled to the relatively low impedance output of a transistor of the power amplifier that is desired to be matched to the predetermined output impedance. Each of the successively coupled microstrip transmission lines has a greater characteristic impedance than the previously coupled microstrip transmission line for achieving the desired impedance match. The series coupled microstrip transmission lines not only match the power amplifier transistor to the predetermined output impedance, but also suppress regenerative oscillations which may occur when the power amplifier transistor is subjected to impedance mismatches. The inventive impedance matching circuitry may be advantageously utilized in the RF signal power amplifier of a base station radio in a mobile radio communication system.

Journal ArticleDOI
TL;DR: In this article, the design, fabrication, and performance of several GaAs FET monolithic circuits are described, including a two-stage, four-FET push-pull amplifier that has exhibited 1.4W output power with 12.4dB gain at 9.0 GHz, and a three-transistor monolithic paraphase amplifier (unbalanced input, balanced output) exhibiting 6dB small-signal gain and a 1-dB gain compression point of 20 dBm.
Abstract: The design, fabrication, and performance of several GaAs FET monolithic circuits are described. These include a two-stage, four-FET push-pull amplifier that has exhibited 1.4-W output power with 12.4-dB gain at 9.0 GHz, and a three-transistor monolithic paraphase amplifier (unbalanced input, balanced output) exhibiting 6-dB small-signal gain and a 1-dB gain compression point of 20 dBm. The amplifier chips utilize monolithically fabricated inductors, capacitors, and transmission lines to accomplish on-the-chip impedance matching.

Journal ArticleDOI
TL;DR: In this article, a new type of radio transmitter using power MOS-FETs was presented, which has a drain efficiency of 90% due to favorable MOS FET characteristics such as wide-ASO, negative aID/aT* coefficient, no current hogging, and no carrier storage.
Abstract: This paper presents a new type of radio transmitter using power MOS-FETs. This new version employs power MOS-FETs in its RF power amplifier and modulator. An RF power amplifier of push-pull or dual SEPP configuration with a power gain of 20dB easily generates high power in the order of kilo-watts. The new RF power amplifier, having output power of 0.3, 0.4, 0.6, 1.0, 2.0, or 3.0kW, features a drain efficiency of 90% because of favorable MOS-FET characteristics as wide-ASO, negative aID/aT* coefficient, no current hogging, and no carrier storage. The modulator consisting of power MOS-FETs has an efficiency of approximately 90% at 100kHz. (*Variation of the drain current with temperature)

Patent
24 Mar 1980
TL;DR: In this article, a power amplifier is provided with a peak holding means for holding, for a given period of time, a peak value of an input signal or an output signal of a power amplifying element there of and is provided also with a switching means for switching, to a selected value in accordance with an output from the peak-holding means.
Abstract: A power amplifier is provided with a peak-holding means for holding, for a given period of time, a peak value of an input signal or an output signal of a power amplifying element there of and is provided also with a switching means for switching, to a selected value in accordance with an output from the peak-holding means, a dc power supply voltage which is supplied to said power amplifying elements. Such amplifier is able to enhance the power efficiency of the power amplifier as well as to reduce switching noises and to reduce the development of distortions.

Journal ArticleDOI
TL;DR: In this article, a master oscillator power amplifier (MOPA) was evaluated using an electron-beam-excited KrF oscillator and an amplifier, and the amplifier gain as a function of input intensity was determined.
Abstract: A master oscillator power amplifier (MOPA) experiment using an electron‐beam‐excited KrF oscillator and amplifier is described. The amplifier gain as a function of input intensity is determined. A comparison of the measured gain with calculations using a steady‐state analysis yields a determination of the small‐signal gain coefficient and saturation intensity for the amplifier operating with two different gas mixtures. The small‐signal gain is found to be more than an order of magnitude larger than the nonsaturable loss, indicating that efficient energy extraction from the amplifier is possible under the high excitation conditions (1.5–6 MW/cm3) of this study.

Patent
18 Jun 1980
TL;DR: In this paper, a trailing wire antenna coupling and control method for providing maximum voltage limited power output from power amplifiers of a high power low frequency RF transmitter system while varying the inductance of the coupling circuit to present a high resistance load having practically zero reactance to the power amplifier, all during extension and retraction of the antenna toward and from its optimum length, as well as at the optimum length.
Abstract: A trailing wire antenna coupling and control method for providing maximum voltage limited power output from power amplifiers of a high power low frequency RF transmitter system while varying the inductance of the coupling circuit to present a high resistance load having practically zero reactance to the power amplifiers, all during extension and retraction of the antenna toward and from its optimum length, as well as at the optimum length.

15 Jun 1980
TL;DR: In this article, the spectrum characteristics of typical converters and the distribution of radiated Radio Frequency (RF) energy from the terminals (transmitting antenna and rectenna) of a beamed microwave power subsystem are presented for small transmitting and receiving S-band (2.45 GHz) subarrays.
Abstract: Measured characteristics of the spectrum of typical converters and the distribution of radiated Radio Frequency (RF) energy from the terminals (transmitting antenna and rectenna) of a beamed microwave power subsystem are presented for small transmitting and receiving S-band (2.45 GHz) subarrays. Noise and harmonic levels of tube and solid-state RF power amplifiers are shown. The RF patterns and envelope of a 64 element slotted waveguide antenna are given for the fundamental frequency and harmonics through the fifth. Reflected fundamental and harmonic patterns through the fourth for a 42 element rectenna subarray are presented for various dc load and illumination conditions. Bandwidth measurements for the waveguide antenna and rectenna are shown.

Patent
21 Jan 1980
TL;DR: In this article, a Class "B" amplifier circuit with a differential amplifier input circuit is presented. But the output amplifier portion of the circuit includes a pair of complementary, series-connected transistors, each connected in a common-emitter configuration.
Abstract: A Class "B" amplifier circuit in which Class "B" conversion takes place in a converter portion of the circuit in combination with a differential amplifier input circuit, rather than in the output stage. The converter modulates the DC bias current supplied to the differential amplifier input circuit as a function of the input signal, in order to achieve Class "B" operation. The output amplifier portion of the circuit includes a pair of complementary, series-connected transistors, each of which is connected in a common-emitter configuration. The disclosed circuit provides a high input impedance and excellent dynamic range.

Patent
08 Jan 1980
TL;DR: In this article, a bias circuit for single-ended push-pull amplifiers is proposed, which allows class A or class AB operation while substantially reducing the idling current of the output transistors at low input signal levels.
Abstract: A bias circuit for single-ended push-pull amplifiers permits class A or class AB operation while substantially reducing the idling current of the output transistors at low input signal levels. The bias circuit includes a DC current limiting circuit comprised of transistors that are connected between the common output of the amplifier and the bases of the output transistors. The transistors of the DC current limiting circuit limit the idling currents of the output transistors when there is no input signal applied to the amplifier. The bias circuit further includes RC/diode circuits which operate to increase or decrease the bias voltages of the transistors of the DC current limiting circuit corresponding to a decrease or an increase of the output voltage of the amplifier. In this way, the idling currents of the output transistors are changed so as to effectively follow the input signal power.

Patent
09 Oct 1980
TL;DR: In this article, the authors proposed a pulse shaping control in a solid-state transmitter of a pulsed radar for reducing the spectral sidelobe energy being transmitted, which is directed to modulating the shape of the rectangular RF envelope pulses to have substantially continuously rising and falling edges.
Abstract: Generally, pulsed radar transmitters of the solid-state variety generate rectangularly shaped RF envelope pulses having discontinuities in the rise and fall edges thereof. It has been identified that, while maximizing power radiation efficiency, these sharp rise and fall times additionally provide for excessive energy in the spectral sidelobes about the transmission frequency of the radar signal. This excessive spectral sidelobe energy has been found to degrade the performance of closely operating pulsed radars through mutual interference. The present invention provides for pulse shaping control in a solidstate transmitter of a pulsed radar for reducing the spectral sidelobe energy being transmitted. The control is directed to modulating the shape of the rectangular RF envelope pulses to have substantially continuously rising and falling edges. In the preferred embodiment, a bipolar microwave transistor is coupled, in a common base configuration, cascadedly between low and high power amplification stages of the radar transmitter. A rectangularly pulsed RF power signal conducted through the transistor is modulated in accordance with a preshaped pulsed power supply signal supplied to the transistor coincidently therewith to render a corresponding power output RF pulse envelope substantially free of discontinuities in the rise and fall edges thereof.

Patent
31 Jan 1980
TL;DR: In this article, sense voltages representative of transmitter power and the temperature of the transmitter output stage are summed and fed to the input of a high gain amplifier, which provides bias to the transmitter driver stage and thus controls the total transmitter developed power.
Abstract: Sense voltages representative of transmitter power and the temperature of the transmitter output stage are summed and fed to the input of a high gain amplifier. The output of the amplifier provides bias to the transmitter driver stage and, thus, controls the total transmitter developed power. The resulting overall feedback system provides precise transmitter power control and output stage thermal protection.

Patent
25 Jun 1980
TL;DR: In this paper, 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.
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.

Patent
29 Aug 1980
TL;DR: In this article, a wide band, feed forward power amplifier circuit has greater stability when quadrature hybrid devices are used to match the output impedance of the power amplifier with the load.
Abstract: A wide band, feedforward, power amplifier circuit has greater stability when quadrature hybrid devices are used to match the output impedance of the power amplifier with the load.