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Showing papers on "RF power amplifier published in 1985"


Journal ArticleDOI
TL;DR: The outphasing technique (LINC) combines two nonlinear RF power amplifiers into a linear RF power-amplifier (PA) system using saturated class-B PA's and proper selection of the shunt reactance improves efficiency.
Abstract: The outphasing technique (LINC) combines two nonlinear RF power amplifiers into a linear RF power-amplifier (PA) system. The two PA's are driven with signals of different phases, and the phases are controlled so that the addition of the PA outputs produces a system output of the desired amplitude. However, the resultant time-varying impedances presented to the PA's alter their dc power consumption and efficiency. Power and efficiency characteristics are derived for both simple (transformer-coupler) and Chireix (transmission-line-coupler with shunt reactance) outphasing systems using saturated class-B PA's. Simple outphasing systems have the efficiency characteristic of a linear class-B PA. Through proper selection of the shunt reactance, the efficiency of a Chireix outphasing system can be maximized at a specific output amplitude. The average efficiency with various amplitude-modulated signals is determined as a function of shunt reactance. Selecting the shunt reactance to fit the signal can improve efficiency by as much as a factor of 2.

389 citations


Journal ArticleDOI
TL;DR: In this paper, the experimental study of capacitive radio-frequency discharges was performed in mercury vapor at low pressures (10−4−10−2 Torr) and at rf applied voltage below 200 V.
Abstract: The experimental study of capacitive radio‐frequency (rf) discharges was performed in mercury vapor at low pressures (10−4–10−2 Torr) and at rf applied voltage below 200 V. It was found that at pressures less than 10−2 Torr, plasma electrons gain rf energy basically through a noncollisional mechanism at the oscillating potential barrier formed in electrode sheaths. The rf power dissipated in this process turned out to be much larger than that received by electrons through their collisions with neutral atoms in the plasma bulk. Experimental results are in good agreement with the theoretical model of low‐pressure rf discharges developed earlier by one of the authors.

131 citations


Patent
19 Oct 1985
TL;DR: In this article, a matching device uses mutual inductance to couple an NMR radio frequency (RF) coil to an RF power amplifier and RF receiver preamplifier, and provides a way for adjusting the degree of coupling by varying the area of the matching coil available for intercepting the RF flux.
Abstract: A matching device uses mutual inductance to couple an NMR radio frequency (RF) coil to an RF power amplifier and RF receiver preamplifier. The device includes a matching coil connected to the RF power amplifier and preamplifier and which is positioned between the NMR RF coil and a decoupling shield in a region where RF flux density, produced by the NMR RF coil, is maximum. This ensures effective coupling to the NMR RF coil and provides a way for adjusting the degree of coupling (hence, input impedance) by varying the area of the matching coil available for intercepting the RF flux.

85 citations


Journal ArticleDOI
TL;DR: In this article, a high-performance CMOS power amplifier consisting of a new input stager especially suited to power amplifier applications and a variation on a class AB output stage is presented.
Abstract: A high-performance CMOS power amplifier consisting of a new input stager especially suited to power amplifier applications and a variation on a class AB output stage is presented. The amplifier has been fabricated using a conventional silicon gate p-well process. The configuration results in several performance improvements over previously reported high-output current amplifiers without requiring process enhancements. Design details and experimental results are described.

73 citations


Journal ArticleDOI
TL;DR: In this paper, measurements of narrow-band (Δω/ω≤0.02) microwave emission from a tunable (7≤ω/2π≤21 GHz) Raman free-electron laser operating in a single TE11 waveguide mode are reported.
Abstract: Measurements of narrow‐band (Δω/ω≤0.02) microwave emission from a tunable (7≤ω/2π≤21 GHz) Raman, free‐electron laser operating in a single TE11 waveguide mode are reported. Approximately 100 kW of rf power has been observed at an electronic efficiency of 12%, and ∼1 MW of rf power has been generated at a reduced efficiency of 8%. Frequency, gain, and rf power measurements have been carried out for various values of the guide magnetic field, below, above, and near to the resonance between the cyclotron frequency of the guide magnetic field and the frequency associated with the periodic wiggler magnetic field. The results are in very good agreement with the predictions of three‐dimensional free‐electron laser theory.

65 citations


Patent
11 Feb 1985
TL;DR: An impedance matching network for continuously and automatically maximizing RF power transfer to a plasma emission torch includes a dual phase detector network and a variable impedance network as discussed by the authors, which is used to control the detector network.
Abstract: An impedance matching network for continuously and automatically maximizing RF power transfer to a plasma emission torch includes a dual phase detector network. Signals from the detector network control, via a control unit, a variable impedance network.

65 citations


Journal ArticleDOI
D. Boussard1
TL;DR: In this article, the authors present a review of the performance and limitations of feedback and feed-forward techniques for beam loading of RF cavities in high-current circular accelerators and storage rings.
Abstract: Beam loading of RF cavities is a subject of great concern for the design and operation of high current circular accelerators and storage rings. The steady state and transient perturbations of the accelerating voltage by the beam current lead to undesirable beam behaviour, like for instance the onset of instabilities or particle loss by lack of longitudinal acceptance. To some extent, it is possible to alleviate or even completely suppress these effects by a proper control of the RF power amplifier - cavity combination, using feedback or feedforward techniques. Several new developments in this field have taken place during the past years. For instance, the implementation of fast feedback technology, the use of cavity compensation schemes or digital filtering of signals in long delay feedback systems have resulted in considerably improved machine performance. Such techniiques will be reviewed in this paper and their performance and limitations will be presented.

59 citations


Journal ArticleDOI
TL;DR: In this paper, the ion sheath thickness was measured in an O2 discharge for 7-53 Pa pressure and 50-800 W rf power (13.56 MHz) and it was concluded that the discharge can be described as a capacitance with both a parallel and series resistance, the series element being the more important one.
Abstract: rf impedance, dc self‐bias, and ion sheath (dark space) thicknesses are measured in an O2 discharge for 7–53 Pa pressure and 50–800 W rf power (13.56 MHz). Special attention is paid to corrections for reactor stray impedances. It is concluded that the discharge can be described as a capacitance (the ion sheath) with both a parallel and a series resistance, the series element being the more important one. Good agreement is found between optical and electrical measurements of the ion sheath thickness. Evidence is presented that the dc potential difference between plasma and ground and rf electrode can be estimated with reasonable accuracy from the dc self‐bias and the optical dark space thicknesses. Positive ion acceleration in the ion sheath and electron‐neutral collisions in the bulk of the plasma glow account for only part of the total rf power transfer. It is suggested that significant dissipation takes place near the glow‐sheath boundary, although a quantitative description cannot be given yet.

55 citations


Patent
Ikeda Shigeki1
18 Apr 1985
TL;DR: In this paper, a radio communication device comprises a portable communication device and a power amplifier device adapted to accommodate the portable communication devices thereinto for amplifying a transmitter output therefrom.
Abstract: A radio communication device comprises a portable communication device and a power amplifier device adapted to accommodating the portable communication device thereinto for amplifying a transmitter output therefrom. The radio communication device further comprises a detector circuit for detecting that an electrical coupling between the portable communication device and the power amplifier device, thereby effecting a control such that the transmitter output power level is kept at a minimum input level required for the power amplifier device. Thus, this can suppress excessive heat generation in the communication device when the portable communication device is used by being accommodated in the power amplifier device.

50 citations


Journal ArticleDOI
Seigoh Kashiwagi1
TL;DR: In this paper, the collector voltage of the emitter-follower-transistor followed the waveform of the output signal was used to achieve a higher efficiency than the conventional amplifier, and a self-oscillating switching power supply was arranged to vary the power supply output voltage according to the input signal voltage.
Abstract: A new high-efficiency audio power amplifier has been developed. This amplifier consists of a conventional power amplifier and a self-oscillating switching power supply which is arranged to vary the power supply output voltage according to the input signal voltage. The new amplifier achieves a higher efficiency than the conventional amplifier, by making the collector voltage of the emitter-follower-transistor follow the waveform of the output signal. Applying this idea to class A amplifiers, a one-third power dissipation can be achieved compared with the conventional class A amplifier. A power MOSFET is used as a switcher. The switching frequency is from 150 kHz to 300 kHz. The new amplifier shows sufficient favorable characteristics. Switching noise is suppressed to a low noise level, which has no influence on the AM tuner or other audio equipment. By stabilizing the single-ended push-pull (SEPP) output transistors, the amplifier can reproduce high quality tone. The present idea is also applicable to dass B power amplifiers and may be suitable for PA or car audio power amplifiers.

49 citations


Patent
John R. Selin1, Donald N Jessen1
13 Jun 1985
TL;DR: In this article, a transceiver transmit/receive switching arrangement for electrically decoupling the transceiver's receiver circuit from first and second transceiver ports during transmission was proposed.
Abstract: A transceiver transmit/receive (T/R) switching arrangement for electrically decoupling the transceiver's receiver circuit from first and second transceiver ports during transmission, and for electrically decoupling the transceiver's transmitter circuit from the first and second transceiver ports during reception Each such circuit includes an amplifier for amplifying an applied microwave signal and operating with a relatively high output impedance when power is applied thereto Each amplifier is inhibited from amplifying an applied microwave signal when power is removed therefrom First bias means switchably applies power to the transmitter amplifier during transmission and removes power from the transmitter amplifier during reception to switch the relatively high output impedance of such amplifier to a relatively low output impedance Second bias means switchably applies power to the receiver amplifier during reception and removes power from the receiver amplifier during transmission to switch the relatively high output impedance of such amplifier to a relatively low output impedance Additional circuitry in the transmitter circuit couples the amplified microwave signal from the transmitter amplifier to the second transceiver port during transmission, and transforms the relatively low output impedance of the transmitter amplifier to a relatively high impedance at the second transceiver port during reception Similar circuitry in the receiver circuit couples the amplified microwave signal from the receiver amplifier to the first transceiver port during reception, and transforms the relatively low output impedance of the receiver amplifier to a relatively high impedance at the first transceiver port during transmission

Patent
Christopher B. Marshall1
17 Dec 1985
TL;DR: A radio frequency tuning circuit as discussed by the authors consists of an N-path filter and a feedback loop connecting the output of such filter to the input of an RF amplifier to which the RF signal is applied.
Abstract: A radio frequency tuning circuit, for use in a transmitter or receiver, which rejects image frequencies of the frequency band of a supplied RF signal to which it is tuned The circuit comprises an N-path filter and a feedback loop connecting the output of such filter to the input of an RF amplifier to which the RF signal is applied The filter includes a tunable local oscillator and a pair of quadrature related signal paths including mixers therein driven by such oscillator, the outputs of such paths being combined by a summing amplifier which produces the output RF signal The output of the summing amplifier is also supplied to the feedback path, causing the center frequency of the transfer characteristic of the N-path filter to be displaced from the local oscillator frequency The RF output signal thereby includes substantially only single sideband of the signals produced by the two signal paths

Patent
Yoshiharu Tamura1, Katsuji Kimura1
07 Aug 1985
TL;DR: In this article, a battery-powered radio communication apparatus is described, which comprises a power amplifier and a power detector for detecting the output power of the power amplifier, and a gain control circuit controls the gain of the generator in response to the output of the amplifier and the output voltage of the detector.
Abstract: A battery-powered radio communication apparatus is disclosed which comprises a power amplifier and a power detector for detecting the output power of the power amplifier. A supply voltage detector compares a standard voltage with the output voltage of a battery supplying power to the power amplifier. A gain control circuit controls the gain of the power amplifier in response to the output of the power amplifier and to the output of the supply voltage detector so as to prolong, by a certain time, the communicable state of the apparatus prior to battery depletion.

Patent
Colin Richard Smithers1
12 Jul 1985
TL;DR: In this article, a bipolar transistor R.F. power amplifier is operated by determining a set of collector supply voltages located at the onset of gain saturation in the bipolar transistor and using feedback to adjust the collector supply voltage in response to variation in input drive level.
Abstract: A bipolar transistor R.F. power amplifier in which feedback is used to control simultaneously amplitude and phase distortion. The bipolar transistor R.F. power amplifier is operated by determining a set of collector supply voltages located at the onset of gain saturation in the bipolar transistor and using feedback to adjust the collector supply voltage in response to variation in input drive level to operate the bipolar transistor in a mode where gain, phase shift and input impedance are simultaneously linearised, found at the onset of gain saturation. A circuit for determining the selection of collector supply voltages comprises oppositely polarised diode detectors (36, 38) which are connected to the input and output circuits of the amplifier (24). Outputs of the diode detectors (36,38) are applied to a differential amplifier (44) which controls a modulated power supply unit (46) for varying the collector voltage. Preferably the power supply unit is a switched mode power supply unit.

Patent
16 Dec 1985
TL;DR: In this article, the muting apparatus provided for eliminating noise signals associated with turn-on and turn-off operations of an audio switching power amplifier is disclosed, which disables the output power amplifiers and controls signal levels at various positions in the power amplifier to reduce transient conditions.
Abstract: In an audio switching power amplifier, muting apparatus provided for eliminating noise signals associated with turn-on and turn-off operations of the apparatus is disclosed. The muting apparatus disables the output power amplifiers and controls signal levels at various positions in the power amplifier to reduce transient conditions. Control apparatus applies the muting signals to the power amplifier during a predetermined period during start-up of the amplifier and applies the muting conditions immediately upon the turning off of power to the power amplifier.

Patent
12 Apr 1985
TL;DR: In this article, a relatively small amount of high frequency RF power is mixed with a predominantly low-frequency RF power to provide an improved etch rate uniformity of a semiconductor wafer in a low frequency plasma etching system.
Abstract: A relatively small amount of high frequency RF power is mixed with a predominantly low frequency RF power to provide an improved etch rate uniformity of a semiconductor wafer in a low frequency plasma etching system.

Patent
18 Jun 1985
TL;DR: In this article, the amplitude and phase of the input signals to an RF amplifier (18) are controlled as a function of the amplitude, respectively, of the output signals from the RF amplifier, and also the amplitude of the inputs are adjusted so as to cause the power of the outputs to vary in accordance with a predetermined sequence.
Abstract: An RF amplifier arrangement for providing output signals having a controlled frequency distribution and wherein the amplitude and phase of the input signals to an RF amplifier (18) are controlled as a function of the amplitude and phase, respectively, of the output signals from the RF amplifier (18) and also the amplitude of the input signals are adjusted so as to cause the power of the output signal to vary in accordance with a predetermined sequence, whereby such amplitude control of the input signals results in a modified frequency distribution in the energy of the output signals.

Patent
Stefan A. Siegel1
06 Jun 1985
TL;DR: A transimpedance amplifier for data signals from a high impedance source includes a forward voltage amplifier and a feedback resistance as discussed by the authors, which is controlled by a differentiator which generates pulses for each data transition and an average detector which generates a control signal responsive to the number of transitions per unit time, which is the data rate.
Abstract: A transimpedance amplifier for data signals from a high impedance source includes a forward voltage amplifier and a feedback resistance. The feedback includes an FET. The resistance of the FET is controlled by a control signal derived from the data signal at the output of the transimpedance amplifier by a differentiator which generates pulses for each data transition and an average detector which generates a control signal responsive to the number of transitions per unit time, which is the data rate. The resistance of the FET is high when the data rate is low, reducing the noise magnitude and decreasing the noise bandwidth. When the data rate increases, the resistance of the FET decreases, providing greater bandwidth for handling the signal. The change in gain caused by the bandwidth control tends to change the magnitude of the output data signal. This may be corrected by an AGC loop which controls the open loop gain of the voltage amplifier. In order to reduce the effect of differences in the bit transition time, a limiter may be coupled to the bandwidth control signal generator.

Journal ArticleDOI
TL;DR: In this article, the authors describe the JET-TFR antenna designed for launching ICRF waves in TFR from the low magnetic field side of the torus, and the main experimental observations on plasma-wave interaction.
Abstract: The paper describes the JET-TFR antenna designed for launching ICRF waves in TFR from the low magnetic field side of the torus, and the main experimental observations on plasma-wave interaction. Compared with a first design of a similar antenna, this antenna design includes new features, such as carbon lateral protections and a thick Faraday shield similar to the one which will be mounted on the JET antennas. Experiment shows that such a shield does not limit the coupling efficiency of the magnetosonic wave in the plasma, the loading resistance being comparable with the one predicted by theory assuming an ideal Faraday shield. With this system, the power coupled reached 600 kW. In the minority regime and for a central electron density around 1014cm−3, the ion central heating efficiency reaches 0.6–0.7 eVkW−1 for an RF power up to 350 kW and 0.5 eVkW−1 at 600 kW. As expected for a low-field-side antenna, no appreciable heating is observed in the mode conversion regime. Spectroscopic measurements show that, in all regimes, the RF pulse introduces a significant amount of both high-Z and low-Z impurities; at the end of a 300 kW/100 ms RF pulse, the total power radiated by the metallic impurities reaches 125–200 kW. The mechanisms responsible for such a generation of metal in the plasma remain unclear, but it can be said that a direct plasma-wave interaction in the scrape-off layer of the tokamak discharge is probably a determining factor.

Journal ArticleDOI
TL;DR: In this paper, the authors compared the performance of a two-and four-cavity high-harmonic gyroklystron with both small-signal analytic theory and large-Signal numerical calculations which assess gain, bandwidth, sensitivity to longitudinal velocity spread, self-oscillation, and saturation characteristics.
Abstract: The high-harmonic gyroklystron is a compact RF amplifier which relies on the synchronous interaction between large-orbit axis-encircling electrons and high-order azimuthal cylindrical cavity TEn11 modes. Because of this unique structure, it offers the promise of moderate- to high-millimeter-wave output power. Experimental results for a fifth-harmonic two-cavity device are compared to both small-signal analytic theory and large-signal numerical calculations which assess gain, bandwidth, sensitivity to longitudinal velocity spread, self-oscillation, and saturation characteristics. Principal theoretical results include the transition to infinite gain as the start-oscillation current threshold is reached as well as the demonstration of the insensitivity of the small-signal gain to parallel velocity spread. The required high-energy rotating electron beam is provided through gyroresonant RF acceleration. To date, over 20 dB of small-signal gain has been achieved at 11.3 GHz in a 1.3-kG magnetic field. The design of a four-cavity configuration is also presented along with simulation of its gain, bandwidth, amplitude modulation (AM) and phase modulation (PM) sensitivity, dependence upon guiding-center spread, and large-signal saturation characteristics. This device has been constructed and initial tests have yielded a gain of 30 dB. Gain in excess of 50 dB is predicted.

Patent
29 Apr 1985
TL;DR: In this article, a proportional audio power demand system with a plurality of speaker banks and amplifiers has been proposed, where each speaker bank has at least one speaker and each amplifier has at most one speaker.
Abstract: A proportional audio power demand system has a plurality of speaker banks and a plurality of amplifiers. Each speaker bank has at least one speaker. The system also has at least one audio channel and each amplifier and speaker bank can be selectively coupled to the audio channel. The system includes a controller which causes at least one amplifier and speaker bank to be coupled to the channel. The system also includes a sensor which senses the power output of the amplifier. The sensor is coupled to the amplifier and controller and the controller responds to the sensed power output of the amplifier to determine when to cause an additional amplifier to be coupled to the channel.

Patent
29 May 1985
TL;DR: A 2-18 gigahertz monolithic distributed amplifier using dual-gate gallium arsenide field effect transistors for maximum gain over the design bandwidth was proposed in this article.
Abstract: A 2-18 gigahertz monolithic distributed amplifier using dual-gate gallium arsenide field effect transistors for maximum gain over the design bandwidth.

Journal ArticleDOI
TL;DR: In this paper, the authors used the particle and power balance model to model the ion particle and energy balance in tandem mirror end cells and found that the highest density and average ion energy are achieved with the resonance closest to the midplane.
Abstract: Fueling and heating of tandem mirror end cells by rf at the ion‐cyclotron frequency have been studied experimentally in the Phaedrus Tandem Mirror. The end cell density is found to increase linerly with rf voltage. The total plasma energy is observed to increase with rf power with no evidence of saturation at high power. The plasma axial length decreases with increasing rf power down to a length of approximately the distance between the two resonance locations in the end cell. The highest density and average ion energy are achieved with the resonance closest to the midplane. It is necessary to assume that the rf electric field at the resonance decreases with increasing density and with distance from the antenna in order to model the ion particle and power balance. The particle and power balance model predicts that dense, hot end cells may be maintained with E+∼1 V/cm and a fueling efficiency of a few percent when the resonance is close to the midplane because of better ion confinement and small plasma vol...

Journal ArticleDOI
TL;DR: In this paper, the design and performance of a GaAs direct-coupled preamplifier and main amplifier is described, which are fabricated by the self-aligned implantation for n/sup +/ -Iayer technology (SAINT) process.
Abstract: The design and performance of a GaAs direct-coupled preamplifier and main amplifier is described. The amplifiers are fabricated by the self-aligned implantation for n/sup +/ -Iayer technology (SAINT) process. The developed preamplifiers have 13-dB gain, 3-GHz bandwidth, and 4.8-dB noise figure for the one-stage amplifier, and 22-dB gain, 2.7-GHz bandwidth, and 5.6-dB noise figure for the two-stage amplifier. The developed four-stage main amplifier has 36-dB gain and 1.5-GHz bandwidth with a power consumption of 710 mW. These amplifiers are promising candidates for application to high-speed data communication systems.

Journal ArticleDOI
TL;DR: In this article, a study of the steady-state discharges and the spatial distributions of plasma parameters vertical to the magnetic field was made in an rf magnetron with oval cross section.
Abstract: A study of the steady‐state discharges and the spatial distributions of plasma parameters vertical to the magnetic field was made in an rf magnetron with oval cross section. Langmuir probes were used for the major diagnostics. The device generates low‐ion energy, high‐ion flux stable plasma (Ei∼102 eV, Γi∼5 mA/cm2 at 1 W/cm2 rf power). Ion transport toward the positive sheath is enhanced by the rf induced dc electric field in the uniform glow. The state of the glow is independent of rf power except ion density ni∝ (rf power)α. The voltage drop across the sheath follows V∝(rf power) β with 0<α<β<1. The discharge strongly depends on magnetic field strength and system pressure, and weakly depends on the gas chemistry. Generally, the state of the discharge is determined by charged particle generation, transport and loss processes, and in turn controlled by the system operating parameters. The experimental results obey the conservation laws and the steady‐state criterion. The correlations between plasma parame...

Patent
21 May 1985
TL;DR: In this article, a four-terminal integrated circuit high-frequency RF amplifier connects to external circuitry via a ground terminal, and RF input terminal, an RF output terminal and a DC biasing terminal.
Abstract: A four-terminal integrated circuit high-frequency RF amplifier connects to external circuitry via a ground terminal, and RF input terminal, an RF output terminal and a DC biasing terminal. A two stage amplification architecture is employed--a current gain transistor (common-emitter) is cascoded with a subsequent voltage gain transistor (common-base) while yet maintaining RF signal inversion overall from input to output so as to increase stability. A biasing current-mirror transistor provides biasing current to the current-gain transistor. A fourth transistor connected as a forward-biased collector-base shorted diode between the current mirror biasing transistor and a common external biasing terminal supplies bias current to the current-mirror biasing transistor while simultaneously minimizing voltage swings across the current-gain transistor. The amplifier module has very low input capacitance which does not change appreciably with changes in load impedance, and operates with great stability under a wide range of different input and output conditions and RF frequencies. Because of its relative simplicity and compactness, the amplifier can be used to great advantage as an IC "building block" in a variety of different applications.

Patent
14 Mar 1985
TL;DR: In this paper, an analog multiplier circuit for multiplying X and Y input voltage signals and using two differential amplifiers to produce a multiplied output is presented, in which separate pairs of transistors provide base drive currents to the amplifier transistors, one pair being associated with each amplifier.
Abstract: An analog multiplier circuit for multiplying X and Y input voltage signals and using two differential amplifiers to produce a multiplied output, in which separate pairs of transistors provide base drive currents to the amplifier transistors, one pair being associated with each amplifier. Trimming voltages are applied between the bases of each transistor pair to independently adjust the base voltage offsets. Nonlinearities between the multiplier output and the X input are reduced by appropriate trimming of the transistor base voltage differentials. Each of the differential amplifier transistors has a common base connection with a matching transistor that carries a current which is complementary to the amplifier transistor current with respect to the Y input signal, thereby reducing output nonlinearities with respect to the Y input signal by making the total base drive currents of both transistors substantially independent of the Y voltage signal. Separate current sources also supply the standing base currents for the transistors of one of the amplifiers, thereby correcting for static imbalances in the base drive circuitry.

Journal ArticleDOI
TL;DR: In this paper, the first step toward building a 35 MW, S-band lasertron for a proof-of- principle demonstration is described. But, this is not the case for the present project.
Abstract: A lasertron (a microwave "triode" with an RF output cavity and an RF modulated laser to illuminate a photocathode) is a possible high power RF amplifier for TeV linear colliders. As the first step toward building a 35 MW, S-band lasertron for a proof of principle demonstration, a 400 kV dc diode is being designed with a GaAs photocathode, a drift-tube and a collector. After some cathode life tests are made in the diode, an RF output cavity will replace the drift tube and a modelocked, frequency-doubled, Nd:YAG laser, modulated to produce a 1 us-long comb of 60 ps pulses at a 2856 MHz rate, will be used to illuminate the photocathode to make an RF power source out of the device. This paper discusses the plans for the project and includes some results of numerical simulation studies of the lasertron as well as some of the ultra-high vacuum and mechanical design requirements for incorporating a photocathode.

Patent
Scott W. Kennett1
06 Nov 1985
TL;DR: In this article, a pulse modulated amplifier is described, comprising a power transistor having a grounded base, an emitter for receiving a drive signal to be amplified, and a collector for emitting a high frequency pulse.
Abstract: A pulse modulated amplifier is described comprising a power transistor having a grounded base, an emitter for receiving a drive signal to be amplified, and a collector for emitting a high frequency pulse, the power transistor operating over a substantially 360° conduction angle variation during which the drive signal is amplified. The pulse modulated amplifier preferably includes a pulse modulator for generating a modulation drive voltage, and a current driver circuit responsive to the modulation drive voltage for generating a control current. The control current is applied to the emitter of the power transistor to control the output power of the emitted high frequency pulse. For a given drive signal the conduction angle of the power transistor is proportional to the control current, and for a given control current the conduction angle of the power transistor is inversely proportional to the drive signal. Accordingly, the instantaneous conduction angle of the power transistor varies throughout the generation of the high frequency pulse such that the pulse amplifier transitions from Class A through Class AB to Class C operation.

Proceedings ArticleDOI
TL;DR: In this paper, the design, fabrication, and microwave performance of a monolithic four-stage GaAs dual-gate FET amplifier is described, and a linear gain of 23 dB with 250 mW output power has been measured at 18 GHz.
Abstract: The design, fabrication, and microwave performance of a monolithic four-stage GaAs dual-gate FET amplifier are described. A linear gain of 23 dB with 250 mW output power has been measured at 18 GHz. The highest power obtained was 500 mW with 21 dB gain at the same frequency. By varying the second gate bias voltage, a dynamic gain control range of more than 60 dB has been observed. The chip size is 6.45mm x 2.1mm x 0.1mm.