Showing papers on "Amplifier published in 1980"

Solid State Radio Engineering

Abstract: Radio Communication Systems. Electrical Noise. Resonant Circuits and Impedance Transformation. Small--Signal High--Frequency Amplifiers. Sinewave Oscillators. Phase--Locked Loops. Mixers. Modulation. Amplitude Modulation Receivers. FM and PM Receivers. Television Receivers. Linear Power Amplifiers. Tuned Power Amplifiers. High--Efficiency Power Amplifiers. CW, FN, and AM Transmitters. Single--Sideband Transmitters. Index.

The multipass amplifier: Theory and numerical analysis

Abstract: Theoretical and numerical analysis of the multipass amplifier illustrates its flexibility in applications ranging from efficient high‐power pulse amplification to short‐pulse generation with great amplitude and pulse‐width stability.

Dynamic CMOS amplifiers

Abstract: A family of dynamic CMOS amplifiers is presented and discussed. First, the concept of dynamic circuit is introduced. Then two groups of circuits with different biasing principles are shown, and experimental results are presented. The advantages of dynamic amplifiers are low power consumption, high voltage gain, large bandwidth, and low offset voltages.

Application of RF Circuit Design Principles to Distributed Power Converters

Abstract: The application of RF circuit design principles to high-frequency power converters is described. Compared to conventional converter design, emphasis is placed on obtaining sinusoidal-type waveforms (instead of rectangular-type waveforms) to minimize device switching time requirements and alleviate transforming requirements. A 25-W 48-V to 5-V dc-to-dc converter design using a 5-MHz switching frequency is presented illustrating these principles, using a Class E power amplifier, an L section impedance transformer, and a shunt-mounted harmonically tuned rectifier circuit. Computer simulation results are presented that indicate the feasibility of the proposed design approach, specify required circuit parameters and indicate that line and load regulation can be achieved with narrow-band frequency control. Experimental results on a low power 5-W, 25-V to 5-V dc-to-dc converter breadboard using a 10-MHz switching frequency with the described circuit topology are presented. An efficiency of 68 percent was obtained and load regulation by frequency control demonstrated. Inductor Q requirements limit the conversion efficiency of the proposed converter, and will probably be the limiting factor in obtaining high efficiency with similar design approaches.

A high performance low power CMOS channel filter

Abstract: A new CMOS PCM channel filter is described, which includes transmit and receive filters on a single die. This chip displays an idle-channel noise of typically 0 dBrnC0, a power supply rejection ratio of 40-50 dB at 1 kHz, and a fully operational power dissipation of only 35 mW, making it very cost effective in telecommunication switching systems. The design of this chip, including architectural, switched capacitor filter, and amplifier considerations is described, and typical experimental results are presented.

Intermodulation Distortion Analysis of MESFET Amplifiers Using the Volterra Series Representation

Abstract: Third-order intermodulation distortion generated in a MESFET amplifer is analyzed by means of the Volterra series representation. A transistor model is used which enables direct analytical determination of the nonlinear elements from small-signal measurements. The four nonlinearities considered are the gate capacitance, transconductance, drain feedback capacitance, and output conductance. Volterra transfer functions are derived for a simplified model and closed-form expressions for the third-order intermodulation ratio and intercept point are determined. The equations show the dependence of distortion on frequency, terminating impedances, and transistor parameters. Principal sources of distortion are identified and the influence of device parameters and network terminations is investigated. Experimental verification on specific MESFET amplifiers, with 2-mu m and 1-mu m gate devices, comparing predicted and measured intermodulation products for various load conditions is presented.

The Matched Feedback Amplifier: Ultrawide-Band Microwave Amplification with GaAs MESFET's

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.

Apparatus for determining the distance to a concealed conductive object which is radiating an alternating current signal

Abstract: An apparatus to measure the distance to a concealed conductive object, radiating an electromagnetic signal, has two sensors, each adapted to receive the signal and to produce an output voltage proportional to the amount of signal received. Amplifier means amplify the output voltage. Automatic gain control means automatically controls the gain to the amplifier means such that the gain of the amplification of one of the output voltages is the same as the gain of the amplification of the other output voltage. Computing means calculate the distance based upon the two amplified output voltages. Display means display the calculated value.

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.

High power efficient dye amplifier pumped by copper vapor lasers

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.

Electro-optical illumination control system

Abstract: Control of illumination with illumination amplifier devices provides a basis for implementing various types of illumination systems. Also illumination amplifiers in closed illumination servo loops provide improved illumination control. An illumination control system provides precise control of camera operations for photographic and photoplotter applications. Illumination amplifier devices are used in conjunction with electronic control circuits to provide flexibility and precision in camera systems, reducing reliance on prior art mechanical devices. Illumination control circuits are presented in the form of digital gates and flip-flops and in the form of analog computational elements to provide illumination computer systems. In addition, a batch fabricated illumination computer arrangement is presented for improved implementation of illumination control systems. Illumination amplifiers are further configured for control of illumination in buildings and automobiles. Various types of devices such as windows, shutters, shades and visors are configured with illumination amplifiers to provide electronic control of illumination. Batch fabricated display arrangements are provided having an illumination source integral with an illumination amplifier for low cost, small volume, and flexibility. Also, colored display arrangements are provided for control of colors with illumination amplifier devices. A projection illumination amplifier arrangement is provided having high-intensity large-screen capability and heat transfer design for cooling.

Characteristics of AlGaAs Fabry-Perot cavity type laser amplifiers

Abstract: Signal gain, saturation power, and noise bandwidth, which are important parameters determining preamplifier and linear repeater system performance [1], were measured for an AlGaAs Fabry-Perot cavity type laser amplifier. The unsaturated signal gain increases with the pumping level and a maximum signal gain as high as 27 dB is obtained near oscillation threshold. The saturation output power, at which the signal gain is decreased from the unsaturated value by 3 dB, is -6 to -8 dBm. The beat noise powers between signal and spontaneous emission components were measured. The error rate characteristics of an AlGaAs laser preamplifier and Si photodiode scheme were studied at a data rate of 100 Mbits/s. The experimental results on noise powers and error rate performance are in reasonable agreement with the theoretical analysis given in an accompanying paper [1].

Gain enhancement in Raman amplifiers with broadband pumping.

Abstract: We have observed near-monochromatic gains in a Raman amplifier pumped by a laser with a bandwidth up to 30 times wider than the molecular linewidth. This gain enhancement is obtained when the corresponding temporal fine structure of the pump and Stokes waveforms are superimposed in the amplifier.

Optical data link

Abstract: The disclosed optical data link provides full-duplex, high-data rate optical communications between geographically separate data processing facilities by means of identical optical transceivers. Transmitter optics include an LED and a collimating Fresnel lens for providing a collimated, modulated light beam. Receiver optics include a focusing Fresnel lens and a photoreceptor for converting the impinging modulated light beam into corresponding electrical signals, which are amplified by a gain-controlled amplifier. The LED is selectively translatable along its optical axis to provide focal length correction for temperature-induced focal length distortion, while the photoreceptor is selectively translatable along its optical axis to provide, in addition to focal length correction, a preselected amount of optical energy attenuation. To control the output signal level from the gain-controlled amplifier, a microprocessor in the gain control loop is responsive to a signal level code to selectively enable successive levels of electronic attenuation in the gain-controlled amplifier, and, if the dynamic range of electronic attenuation is exhausted without achieving an optimum output signal level, to selectively adjust the level of optical attenuation by incrementally translating the photoreceptor. To control transmitted signal power, the microprocessor is responsive to a temperature indication code to translate the light emitting diode to the actual focal length of the associated Fresnel lens, thereby correcting temperature-induced focal length distortion and optimizing transmitted signal power.

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.

The use of current amplifiers for high performance voltage applications

Abstract: A current amplifier is used to realize a voltage amplifier having an improved high frequency response and slew rate capability. It is shown that the closed loop bandwidth is independent of the closed loop voltage gain. The design and application of a unity gain and a high gain current amplifier to voltage signal processing circuits are given. The results demonstrate an efficient use of the inherent frequency response capabilities of the active devices in the circuit to achieve the amplification of high frequency and large amplitude voltage signals.

A high gain single stage gyrotron traveling-wave amplifier

Abstract: A high gain gyrotron traveling-wave amplifier. experiment has been performed in which net linear gains exceeding 50 dB have been observed. The experiment, which operates at 35 GHz in the TE 01 circular-electric mode, uses a resistive wall waveguide for stabilization against both reflective instability due to feedback by reflections at the input and output couplers and absolute instability due to feedback by coupling to the backward traveling wave by the electron beam. A 70 kV annular electron beam with a perpendicular velocity to parallel velocity ratio of approximately 1.5 was used, with beam currents up to 3 amps. The experiment supports calculations in showing that bandwidth improvement occurs as an additional benefit of the lossy wall. Also, the gain reduction due to the lossy wall is about one third the cold tube loss implying that stability can be achieved without serious sacrifice of gain.

Multi-channel audio power 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.

Broadly tunable picosecond IR source

Abstract: A picosecond traveling-wave parametric device capable of controlled spectral bandwidth and wavelength in the infrared is reported. Intense 1.064 μm picosecond pulses (1) pass through a 4.5 cm long LiNbO 3 optical parametric oscillator crystal (2) set at its degeneracy angle. A broad band emerges, and a simple grating (3) and mirror (4) arrangement is used to inject a selected narrow-band into a 2 cm long LiNbO 3 optical parametric amplifier crystal (5) along a second pump line. Typical input energies at 1.064 μm along both pump lines are 6-8 mJ for the oscillator and 10 mJ for the amplifier. This yields 1 mJ of tunable output in the range 1.98 to 2.38 μm which when down-converted in a 1 cm long CdSe crystal mixer (6) gives 2 μJ of tunable radiation over the 14.8 to 18.5 μm region. The bandwidth and wavelength of both the 2 and 16 μm radiation output are controlled solely by the diffraction grating.

Thermal resistance of GaAs field-effect transistors

Abstract: Characterization of the thermal resistance of GaAs FETs is presented. An electrical method of measuring it is first described. An anomaly in the thermal resistance discovered at high temperature is explained, Experimental findings are discussed on the theoretical background. Practical expressions are then derived for the thermal resistance in terms of device geometry and channel temperature. The expressions are verified to be accurate in comparison with our experimental results and with the measured values obtained by infrared microscopes elsewhere. They are useful not only for designing power GaAs FETs but also for optimizing the amplifier performance.

A true logarithmic amplifier for radar IF applications

Abstract: There are certain radar receivers where the settling time of an AGC loop is unacceptable and an amplifier is required which will compress the dynamic range instantaneously. A common technique for accomplishing this is to use a logarithmic amplifier. This has other advantages in radar applications in that a logarithmic amplifier can assist in separating wanted signals from unwanted signals known as `clutter' caused by unwanted targets such as raindrops. In systems such as MTI radar systems, where it is required to detect moving targets, the phase information is important hence the logarithmic output must be at the IF frequency. In order to preserve the phase information the phase shift or delay through the log amplifier should not vary with input signal level. This type of amplifier is known as a true logarithmic amplifier. The device described in this paper is capable of producing a true logarithmic amplifier with phase matching of /spl plusmn/4/spl deg/ over an 80 dB input dynamic range at 70 MHz.

Gain and saturation power of resonant AlGaAs laser amplifier

Abstract: Results of gain measurements on an AlGaAs laser amplifier with an optical isolator are reported. The maximum net gain was 25 dB when input power was less than ?40 dBm. By measuring internal loss, a saturation parameter was estimated to be 6 mW.

Radio transmitter energy recovery system

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.

Cascadable Monolithic Balanced Amplifiers at Microwave Frequencies

Abstract: A cascadable monolithic amplifier where input-output decoupling is obtained through new broad-band, low-loss coplanar directional couplers, is reported. Design data and experimental results are given for the new couplers which are suitable for both hybrid and monolithic circuit applications. The main faitures of the prototype X-band monolithic balanced amplifier are stressed. Finally, low-loss slow-wave structures for monolithic circuit design are briefly presented.

Middle and upper atmosphere radar (MUR) under design in Japan

Abstract: A large MST radar for observing backscattering from refractive index fluctuations in the middle and upper atmosphere is now under design in Japan. The proposed system is a pulse-modulated monostatic radar, working at a frequency near 48 MHz. The configuration will be quite different from the existing MST/ST radars. A quasi-square array with an aperture of 104 m2 is composed of 456 Yagi antennas, each of which is provided with a low-power amplifier. A peak output power of more than 1 MW is envisaged to be generated when the whole system is coherently activated. In this system a phase shift is obtainable at a low power level by variable phase shifters controlled by electronic means, which enable rapid and continuous scanning of the antenna. The whole system is monitored and controlled by a microcomputer network.

GaAs-GaAlAs phototransistor/laser light amplifier

Abstract: A hybrid light amplifier consisting of a GaAs-GaAlAs widegap phototransistor as light detector and a d.h. laser as light emitter has been realised. Amplification up to 25 dB has been achieved. Fastest turn-on and turn-off times were 16 ns and 24 ns, respectively. A monolithically integrated amplifier structure is proposed.

Variable delay circuit for emulating word line delay

Abstract: A semiconductor memory having an address buffer (10), row decoder (12), word lines (16), bit line (20) and sense amplifier (22) for accessing individual memory cells in an array of memory cells. In order to emulate worst case delays experienced in the word lines in accessing the last cells in the rows in order to prevent the sense amplifiers (22) from reading the bit lines (20) too soon, a tunable delay circuit (30) delays actuation of the sense amplifier. This circuit is divided into a plurality of impedance section with associated parasitic capacitance where groups of sections are bypassed by switching devices such as MOS transistors. The delay of a signal propagating through this tunable delay circuit can be varied by bypassing varying numbers of the sections with the switching devices.

Analysis and design of integrated electronic circuits

Abstract: Semiconductors and the p-n Junction Diode The Junction Transistor The Field Effect Transistor Integrated Circuit Fabrication Graphical Analysis Linear Models for Electronic Devices Pulse and Large-Signal Models for Electronic Devices Fundamental Elements of Digital Systems Logic Families Sequential Circuits and Their Design Memories Small-Signal Untuned Amplifiers - Broadband Amplifiers Operational Amplifier Applications Operational Amplifier Circuitry - The Practical Operational Amplifier Untuned Power Amplifiers Feedback Amplifiers Bandpass Amplifiers Oscillators Power Supplies.

Generation of stable frequency radiation at an optical frequency

Abstract: Stable-frequency optical radiation is generated by use of an electro-optical modulator to produce from radiation of a power laser that has inherent frequency fluctuations, an optical side band of the radiation that has the stable frequency. A modulating signal is applied to the modulator (12), the signal based upon a difference-frequency signal that represents the difference in frequencies between the output of the power laser (10) and an optical signal obtained from a highly stable reference source (20). The reference radiation shown is the direct output radiation of a stable reference laser. In one embodiment the pulses of a high power CO u TEA laser operating on a single mode are synchronized with a pulsed broad band amplifier (22) which amplifies the difference-frequency signal to produce the modulating signal, and an optical delay (30) in the power laser output path, preceding the modulator, corrects for the delay provided by the amplifier and other sources of delay The invention provides chirp free pulsed lasers, and lasers having stable frequency from pulse to pulse. Improved doppler lidar and other lidar systems are provided that utilize the stabilized output as the probing radiation.

Control circuit for DC motors

Abstract: There is provided a control circuit for a DC brushless motor suitable for use in acoustic devices or data cassette recorders which comprises a rotor magnet rotating synchronously with the motor rotor, three or more-phase stator windings opposing the rotor magnet and spaced apart therefrom by a slight gap, winding drive circuits for supplying exciting current to the stator windings, and Hall elements for detecting angular positions of the rotor magnet and producing output voltages supplied to the winding drive circuits. The control circuit further comprises a limit voltage setting circuit for setting two limit voltages respectively having upper and lower amplitudes which are symmetrically variable with respect to the central potential of the upper and lower amplitudes, an amplifier circuit associated with each of the Hall elements and amplifying the output voltage from the Hall element with respect to the central potential, and an amplitude limiter circuit limiting upper and lower amplitudes of the amplified output voltage from the amplifier circuit not to exceed the two reference voltages, thereby producing a trapezoidal waveform which in turn is applied to the winding drive circuit.