Showing papers on "RF power amplifier published in 1983"

Large swing CMOS power amplifier

Abstract: A CMOS class AB power amplifier is presented in which supply-to-supply voltage swings across low-impedance loads are efficiently and readily handled. The amplifier consists of a high-gain input stage and a push-pull unity-gain amplifier output stage. The amplifier dissipates only 7 mW of DC power and delivers 36 mW of AC power to a 300-/spl Omega/ load, using standard power supplies of /spl plusmn/5.0 V. Lower impedance loads can be driven to higher power levels, providing the internal current limiting level is not exceeded.

Effects of the collector current fall time on the class E tuned power amplifier

Abstract: Presents the equations governing the operation of the amplifier when the collector current fall time during the on-to-off transition of the transistor is an appreciable fraction of the signal period. A current-source model of the transistor with a linearly decreasing collector current during the fall time is used. The following basic amplifier parameters are determined: the waveforms of the collector current, the collector-to-emitter voltage, the instantaneous power dissipated in the transistor, the optimum values of the load-network components, the output power, the power-output capability, and the collector efficiency. The decrease of the collector efficiency is e.g. 10 percent at 60/spl deg/ fall time. Experimental results are also given. The author shows the behavior of the class E amplifier at higher operating frequencies and provides more accurate circuit design procedure.

2-20-GHz GaAs Traveling-Wave Power Amplifier

Abstract: Power amplification in FET traveling-wave amplifiers is examined, and the mechanisms which limit power capability of the amplifier are identified. Design considerations for power amplification are discussed. A novel single-stage and two-stage monolithic GaAs traveling-wave power amplifier with over 250-mW power output in the 2-20-GHz frequency range is described.

Exact analysis of class E tuned power amplifier with only one inductor and one capacitor in load network

Abstract: Presents an exact analysis of that amplifier, an accurate and simple design procedure, and experimental results which confirm the theoretical analysis. The following performance parameters are determined for optimum operation with any switch duty ratio: the current and voltage waveforms, the peak values of collector current and collector-to-emitter voltage, the output power, the power-output capability, and the component values of the load network. The output harmonic spectrum is given for several values of switch duty ratio. The transistor power losses and collector efficiency are also estimated. The measured collector efficiency was over 95 percent with 3 W output power at 1 MHz, using a BSX60 TO-39 transistor.

Combined microwave parallel amplifier- RF attenuator/modulator

Abstract: A parallel channel microwave amplifier comprising a plurality of amplificon channels interconnecting a power-dividing matrix and a power-combining matrix. Each amplification channel includes a phase shifter, an attenuator and a power amplifier connected in series. The device functions as a combination of amplifier and an r.f. attenuator/modulator.

Low noise CATV converter

Abstract: A low noise frequency converter particularly adapted for the large bandwidth environment encountered in extended bandwidth cable television (CATV) systems is disclosed. The CATV converter includes an upconverter/downconverter combination for translating the received RF signal to an intermediate frequency (IF) carrier signal. A first IF signal is generated by heterodyning the received RF signal with the output of a voltage controlled oscillator in a first double balanced mixer. The upconverted signal thus produced is then mixed in a second double balanced mixer with the reference output of a second local oscillator to provide a fixed, downconverted second IF carrier signal. The upconverter portion of the CATV converter includes a pin diode attenuator between an RF amplifier and the first double balanced mixer. The pin diode attenuator is driven by the RF amplifier and is regulated by the signal receiver's automatic gain control (AGC) system permitting signal level to be increased at a faster rate than noise figure resulting in an improved converter signal-to-noise ratio and improved large signal handling capability. The downconverter portion of the CATV converter includes a double balanced diode mixer between the first IF amplifier and the second IF amplifier. With the double balanced diode mixer for the second mixer in the downconverter section, cross-modulation and intermodulation distortion from adjacent channels is reduced. In addition, the double balanced diode mixer provides an improved overall noise figure due to its lower noise performance than that available with either a single ended diode mixer or active mixer.

Output power control circuit for power amplifier

Abstract: An output power control circuit provided with a power amplifier circuit of an input amplifier and an output amplifier connected in series with the input amplifier, has: a first transistor having a first electrode connected to a direct current power supply and a second electrode connected to a power supply terminal of the output amplifier; a second transistor having a first electrode connected to a third electrode of the first transistor and a second electrode connected to a power supply terminal of the input amplifier; and at least one diode connected between the direct current power supply and the power supply terminal of the input amplifier.

Low power indicating circuit for a radio transmitter

Abstract: Low power for a radio transmitter is indicated by an output power detector voltage falling below a low power reference voltage derived from an existing power control circuit.

Wideband IF amplifier with complementary GaAs FET-bipolar transistor combination

Abstract: A wideband intermediate frequency (IF) amplifier including a GaAs FET input portion and a bipolar transistor output portion is disclosed. The high gain of the GaAs FET over higher frequencies is complemented by the high gain of the bipolar transistors at lower frequencies to provide high amplifier gain over a large bandwidth. The GaAs FET and bipolar portions are coupled by means of an equalizer circuit matching the two portions together only at the higher frequencies of the IF band to provide an inexpensive, high performance IF amplifier particularly adapted for use in a direct broadcast satellite receiver operating in the super high frequency (SHF) band.

Microwave communications system

Abstract: A microwave transmitter comprises a signal modulator for receiving an input signal that includes up to 75 video and audio channels and producing an amplitude modulated signal in the microwave frequency range corresponding thereto. An amplifier responsive to the microwave frequency signal produces an amplified output signal suitable for transmission to a remote location. The signal modulator and the amplifier have upper power limits which are sufficiently below their respective two-tone third order intermodulation intercept points that the carrier-to-triple-beat power ratios of each are respectively at least equal to first predetermined values. The gain of the amplifier is high enough that, notwithstanding the power limitation imposed on the microwave frequency signal by virtue of the upper power limit of the signal modulating means, the power of the amplified output signal is at least equal to a second predetermined value. The sum of the gain and the noise figure of the transmitter measured in decibels has an upper limit determined by the desired carrier-to-noise ratio and by thermal noise.

Electronic control switch for a power boost amplifier

Abstract: An electronic amplifier control switch for controlled operation of a power amplifier connected to the output of an audio signal generating device and having an associated electronic equalizer/attentuator switching circuit that is switchable between its two modes by a manually settable switch.

Dual Frequency Ring Magnet Power Supply with Flat-Bottom

Abstract: A power supply is described that furnishes an essentially flat-bottom injection field, followed by a dual frequency cosine field. This results in efficient beam capture during injection and reduces significantly the peak rf power required during acceleration in a rapid-cycling synchrotron.

Bootstrapped shunt feedback amplifier

Abstract: An improved bootstrapped shunt feedback amplifier is provided in which a minimum number of transistors are arranged to provide a higher slew rate of output voltage at lower power, while minimizing distortion and thus providing a more precise signal replication. Features include the use of three-terminal composite transistors to increase bandwidth and bootstrapping to improve amplifier response while reducing voltage stress on the active devices.

MOS Power amplifier circuit

Abstract: A MOS power amplifier circuit comprised of a load driver including two p-channel MOSFETs connected in series, a preamplifier for amplifying an analog input signal and supplying the amplified one to the gate of one of the MOSFETs and for rendering the impedance of the two MOSFETs low; and an inverting amplifier for invert-amplifying the output signal from the preamplifier and supplying the amplified one to the gate of the other MOSFET. The operating voltage of the preamplifier and the inverting amplifier is higher than that of the load driver.

Thermocouple power meter

Abstract: An improved meter for measuring RF power. The RF power is applied to thermocouple means which transforms the RF power into a low level d.c. signal which then passes through a chopper stage that is driven by a clamped sinusoidal input. The output of the chopper stage includes periodic pulses with a prescribed pulse spacing: pulse duration ratio, the pulses being passed through a band-pass filter at a harmonic of the chopper drive signal. The filtered signal, which is also amplified, undergoes synchronous detection with a tri-level square-wave signal which is centered in phase relative to the amplified, filtered signal when the two signals are in phase. The power meter measurements adjusted for zero drift and calibration drift by a microprocessor; based on zero measurements and calibration measurements made before and after an RF measurement is made. Measurements are stored and processed digitally to enhance accuracy. Signals through the meter can be at relatively high frequencies to reduce 1/f noise; spiking at the chopper stage and synchronous detector is virtually eliminated; and the tri-level square-wave permits greater tolerance to phase shift, all of which reduce output error.

Low-Noise, Low Power Dissipation GaAs Monolithic Broad-Band Amplifiers

Abstract: Low-noise, low dc power dissipation GaAs monolithic amplifiers have been developed for use in VHF-UHF mobile radio systems. The developed amplifiers have two-stage constuction, where gate width for the first stage is 1000 µm, and for the second stage is 500 pm. Using this circuit configuration, both noise figure and bandwidth have been improved. To maintain the uniformity for the ion-implanted active layers and to reduce gate-source resistance R/sub S/ and gate-drain resistance R/sub D/, the "closely spaced electrode FET" was adopted. The FET enables low drain voltage operation, resulting in low dc power dissipation. The developed amplifier for the FET threshold voltage VT= --0.6 V provides a 3-dB noise figure, less than 170-mW dc power dissipation, 9-MHz-3.9-GHz bandwidth with 16-dB gain. It can operate under a unipolar power source. When external choke inductors were introduced for the amplifier, 120-mW dc power dissipation has been achieved. It has also been demonstrated that the amplifier for V/sub T/= --0.6V, which is inferior to the amplifier for VT= -2.7V regarding gain-bandwidth product and power efficiency under the same dc power dissipation, however, has an acceptable performance for use in the mobile radio systems.

Rf power switches

Abstract: RF switches, for use with radio frequencies, are fast, and require practically no DC energy for maintaining the ON and OFF positions. The switches include a rectifier in series with a capacitor, or with another rectifier in a back-to-back position, or facing each other, or a transistor instead of these two, the rectifier and transistor having an adequate reverse recovery time, these elements being arranged between the RF power source and the load. An inductive element is disposed in series with either the elements of the switch or between the base of the transistor and ground. There may be provided a further diode in series with the inductive element and the switch and in the connection to ground.

Balanced amplifier device

Abstract: A signal amplifier device providing output power independent of change in output characteristics or common mode interference including a signal input source to provide an input signal, a first power supply and second power supply having a transformer with a secondary coil and a reference power, first differential amplifier powered by the first power supply to receive the input signal and provide first and second complementary output signals, first and second output amplifiers driven by the reference power supply and each having an input to receive one of the first and second signals and amplify same to provide first and second output signals at the respective outputs so that upon imposition of a transient signal at the output of one of the first and second output amplifiers an isolation network prevent the transient signal from appearing as a differential signal on either output.

Analog signal power amplifier circuit

Abstract: A signal corresponding to an analog input signal is supplied to one of two input terminals of a two-input, one-output MOS differential amplifier. A reference voltage signal is supplied to the other of the two input terminals of the MOS differential amplifier. A bipolar transistor having one end connected to an analog signal output terminal is driven by a signal from the output terminal of the MOS differential amplifier. A loudspeaker is driven by the bipolar transistor.

Telecommunication operational amplifier

Abstract: A single stage high performance operational transconductance amplifier consists of a pair of p-channel load field effect transistors, a pair of n-channel type cascode field effect transistors, a pair of n-channel differential field effect transistors and an n-channel current source field effect transistor. This amplifier has improved performance in terms of noise and power supply rejection as compared to conventional CMOS amplifiers.

Modular field strength instrument

Abstract: A modular field strength measuring and indicating instrument that includes as one component a sensing module with a sensitive D'Arsonval meter movement and a receptacle for interchangeable plug-in type sensing modules for measuring an electrical condition, such as electrical power. The other component is a field strength sensing module that plugs into the receptacle and which includes a self-contained DC voltage source, a sensing antenna, a high-impedance, variable gain, linear DC amplifier operatively connected to the voltage source for amplifying the field strength voltage signal sensed by the antenna, and circuitry for transmitting the amplifier output voltage signal to the D'Arsonval meter movement for indicating the field strength detected by the instrument. The field strength sensing module may be used in the meter module interchangeable with other modules, such as modules for measuring RF power in RF transmission lines.

Novel adaptive biasing amplifier

Abstract: A novel adaptive biasing amplifier is presented. This amplifier with a very low standby power dissipation has a high driving capability and consumes less power than the previously presented adaptive biasing amplifiers.

Amplifier circuit with automatic gain control and hearing aid equipped with such a circuit

Abstract: An amplifier system comprising an input transducer, an amplifier and an output transducer connected in cascade, and an automatic gain control circuit comprising a variable resistor for taking off a voltage which varies with the signal from the input transducer and supplies said voltage to a rectifier and an RC filter. The filter output is connected to the base of a first transistor having a collector that directly drives the base of a second transistor which is connected to the input of the amplifier in such a way that it bypasses the input signal of said amplifier to a greater extent as the signal across the variable resistor increases.

A New, Specifically Monolithic Approach to Microwave Power Amplifiers

Abstract: A new principle was used to build a GaAs MMIC. X-band Power Amplifier based on a modular tree design where the number of modules increase at each amplifying stage. First experimental data show 10 dB gain at the centre of the operation band (8 - 9 GHz).

The RF Power Plant of the SPS

Abstract: This paper describes briefly the main components of a RF power system with the exception of the accelerating cavity. A diagram of a 200 MHz accelerating system is shown. The power for the accelerating cavities is provided by a 500 kW amplifier utilizing 2, 4, 8 and 16 tetrodes or one 500 kW klystron. The terminating load is a 6 m long 6 1/8'' stainless steel coaxial line. High power transmission lines with coaxial and waveguide components are discussed.

Computer-Corrected Load-Pull Characterisation of Power MESFET's

Abstract: A versatile system for the load-pull characterisation of power MESFET's is described. Computer-aided vector error correction techniques are used at the input and output of the transistor to provide accurate large-signal measurements of reflection coefficient and RF power.

Damping Ring RF System for SLC

Abstract: The linear collider project at SLAC contains two damping rings to reduce the emittance of short electron or positron bunches which contain 5 x 10/sup 10/ particles per bunch. Two of these bunches are stored at a time and then extracted for acceleration in the collider. The rf system is subject to strong transients in beam loading. A computer model is used to optimize capture while minimizing rf power. The introduction of phase jump in the rf drive at injection time together with offsets in the tuning loops of the rf cavities when no beam is stored allows optimum performance under heavy beam load conditions. The rf system (800 kV at 714 MHz) for the electron damping ring has been built, tested and installed, and is being tested with beam.

Transconductance amplifier operable with bipolar input

Abstract: An amplifier for bidirectionally driving a motor includes circuitry for enabling the amplifier to operate with a bipolar input signal while employing a single power supply. The amplifier includes an input section which receives the bipolar input signal and provides a unipolar output voltage. The operational amplifier drives a bridge drive network to provide a drive current to output bridge transistor in one of two directions. The bridge network includes control circuitry for causing all of the transistors of the drive bridge to be operated in their active regions, thereby improving the power dissipation characteristics of the network. The output bridge transistors are also controlled to operate in their active regions. In addition, circuitry is included for providing negative feedback for the amplifier despite the fact that the output current is always a positive current.

GaAs Strip-Coupled Memory Correlators

Abstract: A SAW monolithic memory correlator is examined. The correlator is fabricated on a substrate of GaAs and does not employ overlay films. RF input to the monolithic correlator is accomplished through the use of conventional interdigital transducers. For wide-band waveforms, chirped transducers are employed. The output port of the memory correlator is composed of an interdigital structure, each tap of which forms a GaAs Schottky diode at the edge of the acoustic beam. Resistive channel effects in side-fed Schottky diodes are analyzed and discussed. Detailed operating characteristics for the storage process and its linearity are presented. Similarly detailed analyses of the varactor properties and the correlation process are examined. First principles prediction of the correlator efficiency is shown to be within a few tenths of a dB of the experimental values. Physical bounds on the rf power requirements from the drive circuitry of the memory correlator are presented as a function of the BTproduct for this architecture.

Optical monitoring for rate and uniformity control of low power plasma-enhanced CVD

Abstract: Plasma‐enhanced CVD requires close control of the plasma power density for reproducibility of both deposition rate and spatial uniformity in a radial‐flow reactor. Frequently the low rf power levels needed are not adequately controlled by the output power control of the relatively high power rf generator found in most commercial multipurpose plasma etch/deposition systems. This paper describes very simple and inexpensive broadband optical monitoring of the plasma emission for improved control sensitivity. The technique has the advantage of directly monitoring the plasma intensity, avoiding effects of variable power transmission losses between the rf generator and the plasma. Application to the control of low power plasma‐enhanced CVD of ‘‘SiO2’’ from Ar:SiH4:N2O plasmas, where the monitor signal is almost entirely due to near infrared Ar emission, is described.