Showing papers on "Amplifier published in 1977"

Idealized operation of the class E tuned power amplifier

Abstract: The class E tuned power amplifier consists of a load network and a single transistor that is operated as a switch at the carrier frequency of the output signal. The most simple type of load network consists of a capacitor shunting the transistor and a series-tuned output circuit, which may have a residual reactance. Circuit operation is determined by the transistor when it is on, and by the transient response of the load network when the transistor is off. The basic equations governing amplifier operation are derived using Fourier series techniques and a high- Q assumption. These equations are then used to determine component values for optimum operation at an efficiency of 100 percent. Other combinations of component values and duty cycles which result in 100-percent efficiency are also determined. The harmonic structure of the collector voltage waveform is analyzed and related amplifier configurations are discussed. While this analysis is directed toward the design of high-efficiency power amplifiers, it also provides insight into the operation of modern solid-state VHF-UHF tuned power amplifiers.

CMOS analog integrated circuits based on weak inversion operations

Abstract: A simple model describing the DC behavior of MOS transistors operating in weak inversion is derived on the basis of previous publications. This model includes only two parameters and is suitable for circuit design. It is verified experimentally for both p- and n-channel test transistors of a Si-gate low-voltage CMOS technology. Various circuit configurations taking advantage of weak inversion operation are described and analyzed: two different current references based on known bipolar circuits, an amplitude detector scheme which is then applied to a quartz oscillator with the result of a very low-power consumption (<0.1 /spl mu/W at 32 kHz), and a low-frequency bandpass amplifier. All these circuits are insensitive to threshold and mobility variations, and compatible with a CMOS technology dedicated to digital low-power circuits.

A new approach to gain-bandwidth problems

Abstract: A new idea for treating the broad-band matching of an arbitrary load to a resistive generator leads to a simple technique for the design of a lossless 2-port equalizer. The method is a numerical one, and only utilizes real frequency (e.g., experimental) load impedance data. No model or analytic impedance function for the load is necessary. Nor is the equalizer topology or analytic form of the system transfer function assumed. The arithmetic is well conditioned and the intricacies of gainbandwidth theory are bypassed. An example comparing the method with analytic gain-bandwidth theory is given. Two examples proceeding directly from experimental data are presented. One is the broad banding of a microwave avalanche diode reflection amplifier. The other is the gainbandwidth equalization of a microwave FET amplifier for gain taper and impedance mismatch.

Operational Amplifiers and Linear Integrated Circuits

Abstract: 1. Introduction to Op-Amps. 2. First Experience with an Op-Amp. 3. Inverting and Noninverting Amps. 4. Comparators and Controls. 5. Selected Applications of Op-Amps. 6. Signal Generators. 7. Op-Amps with Diodes. 8. Differential, Instrumentation, and Bridge Amplifiers. 9. DC Performance: Bias, Offsets, and Drift. 10. AC Performance: Bandwidth, Slew Rate, Noise, and Frequency Compensation. 11. Active Filters. 12. Modulating and Frequency Changing with the Multiplier. 13. Integrated Circuit Timers. 14. D to A and A to D Converters. 15. Power Supplies. Answers. Index.

Modular microwave power combiner

Abstract: A modular microwave power combiner having a plurality of identical microwave diode amplifier circuits grouped in sets within the body of a modular unit which are electrically coupled in parallel to a central cavity sized to be resonant at a single frequency to minimize mismoding thereby enhancing combiner efficiency. A number of waveguides are provided for coupling of the microwave diode in each amplifier circuit to the resonant cavity, and the waveguides are situated on one side of a PC board at the top of each modular unit. Since each of the modular units is essentially identical in physical size and shape, the overall power output of the power combiner can be increased by merely adding additional modular units. The individual modular units are sized to fit top-to-bottom such that the respective resonant cavities are spaced apart by one-half wavelength (λ/2) for the parallel electrical coupling of all of the resonating cavities. Each modular unit further includes a water jacket around the diode mounts for conducting heat away from the microwave diode thereby increasing circuit density and decreasing overall housing size.

Harmonic output of class-E RF power amplifiers and load coupling network design

Abstract: Class-E RF power amplifiers have advantages of explicit a priori designability, reproducibility, high efficiency, and low-stress operation of the power output devices. The authors give information on harmonic output and explicit design criteria for harmonic-suppression networks to be used with class-E power amplifiers.

Theory of a two-photon laser amplifier

Abstract: We discuss the propagation of an electromagnetic pulse through an active medium prepared in a state of inversion between two levels of the same parity. Since no electric dipole transition is possible between the chosen atomic levels, we investigate the possibility of amplification of an injected signal having a carrier frequency equal to one-half the atomic-transition frequency. We show that under suitable conditions a nonlinear atomic polarization can be generated which oscillates at the same frequency as the incident electromagnetic pulse. The coupled atom-field evolution is described by the usual self-consistent approach. When atomic relaxation effects are negligible, we derive an equation describing the spatial evolution of the energy of the propagating pulse. From this equation we characterize the threshold condition for power amplification and classify the multiple steady-state solutions of the propagation problem. The evolution of the pulse envelope through the amplifier is analyzed with the help of a hybrid computer simulation. Pulse-envelope modulation and multiple-pulse formation even in the asymptotic limit of long amplifiers are displayed.

Inventing the negative feedback amplifier: Six years of persistent search helped the author conceive the idea “in a flash” aboard the old Lackawanna Ferry

Abstract: The author describes how he came to invent the negative feedback amplifier in 1927.

Thermal noise thermometer

Abstract: A thermal noise thermometer operating on the principle that the temperature of a resistor is related to the magnitude of the thermal noise signal produced in the resistor. The thermoseter comprises a temperature-sensing resistor, a shot noise source, means for selectively applying shot noise signals from the shot noise source to the resistor, a DC amplifier for amplifying the DC signal produced in the resistor, an AC amplifier for amplifying the AC signal produced in the resistor, and means for calculating the temperature to be measured from the output signal of the AC amplifier produced when the shot noise signal is applied to the resistor, the output signal of the AC amplifier produced when no shot noise signal is applied to the resistor, and the output signal of the DC amplifier.

Optical phase conjugation in a lithium formate crystal

Abstract: Optical phase reversal has been demonstrated using type‐II phase matching in lithium formate operated as a degenerate optical parametric amplifier with pump peak powers as low as 103 W. The amplifier was driven in a collimated geometry.

Low supply voltage frequency multiplier with common base transistor amplifier

Abstract: A frequency multiplier circuit utilizing a zero-crossing detector for producing a square wave at the frenquency of the input signal to generate harmonics of the input frequency. The square wave is filtered to generate a signal of a predetermined harmonic.

Ground fault circuit interrupter utilizing a single transformer

Abstract: A single transformer is alternately operated as a differential current transformer with its secondary winding connected as the input to a low impedance differential amplifier with large negative feedback during a ground fault current sampling period and then as a coupled resonant circuit operating into a negative resistance network during a neutral-to-ground resistance sampling period. During the fault current sampling period, the amplifier is gated ON and OFF to switch the transformer secondary loading between essentially short-circuit and open-circuit conditions. The resulting amplifier feedback current pulses, indicative of transformer secondary current, are integrated either directly or indirectly, to develop a DC signal proportional to any ground fault current.

Method of energizing a material

Abstract: This application discloses light amplifier apparatus and uses for the same. A light amplifier apparatus is disclosed in which population inversion is created by optical pumping. Another light amplifier apparatus is disclosed in which population inversion is produced by collisions with other particles. Uses for light amplifiers are taught including heating of material which includes evaporation of the same, distance measuring, communication systems, television, and certain industrial applications. This application also teaches the use of optical elements at Brewster's angle for the purpose of polarization and reducing losses in passing a light beam along a path.

Phased power switching system for scanning antenna array

Abstract: A system for a phased array antenna including a set of power amplifiers for amplifying the power of a signal to be transmitted by radiating elements of the antenna. A set of hybrid couplers are connected between the power amplifiers and the radiating elements with individual ones of the hybrid couplers being cross-connected for sharing the power of each amplifier among a set of radiating elements. The coupling of power is selectively varied between the amplifiers and the radiating elements by shifting the phase of the signal applied to each power amplifier.

Feed-forward amplifier

Abstract: A high-precision amplifier employs a feed-forward technique to provide a first order correction of amplifier distortion. A second amplifier is utilized to sense the base-to-emitter distortion of a main amplifier and develop an error output which is injected into an output node to provide cancellation of distortion from the output of the main amplifier. The feed-forward distortion-correction technique is particularly applicable to high-precision wideband differential amplifiers; however, the technique may be used in other amplifiers as well.

Complementary-symmetry amplifier

Abstract: A complementary-symmetry amplifier is described, wherein a CMOS inverter has its P-channel MOSFET paralleled by the emitter-to-collector path of a simultaneously conductive PNP bipolar transistor and has its N-channel MOSFET paralleled by the emitter-to-collector path of a simultaneously conductive NPN bipolar transistor. The amplifier switches very rapidly due to the high transconductances of the bipolar transistors, while the MOSFET's permit the output terminal of the amplifier to swing over the full range of available supply potential.

Sightless bubble detector

Abstract: A detector comprises a pair of electromechanical transducers for disposition on a fluid-filled conduit in an acoustically coupled relationship, an adjustable gain driving amplifier responsive to the electrical output of one transducer for driving the other transducer, an automatic gain control circuit for automatically adjusting the gain of the driving amplifier maintaining the system on the margin of oscillation, and an indicating circuit for detecting modulation of the driving signal. Bubbles passing through the conduit increase the gain required to maintain the system on the margin of oscillation, and are detected as modulations of the driving signal. In a preferred embodiment, this bubble detector is utilized as a refrigerating system test instrument.

Photosensitive self scan array with noise reduction

Abstract: A noise reduction scheme for a photosensitive self scan system includes an array of photosensitive elements producing video signals and first and second pluralities of switching elements, one element of each of the pluralities of switching elements being connected to one photosensitive element of the array. A first video line connects each element of the first plurality of switching elements to a first input terminal of a summing device such as a differential amplifier and a second video line connects each element of the second plurality of switching elements to a second input terminal of the differential amplifier. Shift register means operated by clock pulses is provided to control the operation of each of the elements of the first plurality of switching elements to sequentially couple the photosensitive elements to the first input terminal and to apply periodically only clock pulse noise signals through the gate drain capacitance of the second plurality of switching elements to the second input terminal of the differential amplifier, so as to produce at the output of the amplifier a video signal substantially free of noise signals created by the clock pulses.

Resonance amplifier model describing diode lasers coupled to short external resonators

Abstract: A model of a regenerative resonance amplifier has been used to describe Fabry-Perot GaAs diode lasers coupled to short external resonators. The optical gain and the equivalent input of the resonance amplifier are controlled by means of appropriate rate equations. Homogeneous line-broadening and proportionality between gain and electron density have been assumed in this approach. The model was applied to a diode laser coupled to an external plane mirror placed at a variable distance from one diode mirror. A numerical evaluation of the coupling coefficient between laser and external cavity enables to predict the measured power output and mode selective properties of the coupled system. A similar analysis was done for diode lasers coupled to external hemispherical resonators. The model calculation confirms the previously demonstrated mode selective properties of the hemispherical configuration which permitted stable single mode operation.

Measurements and modeling of gain coefficients for neodymium laser glasses

Abstract: Small-signal gain coefficients are reported for neodymium in silicate, phosphate, fluorophosphate, and fluoroberyllate laser glasses. Measurements were made in a disk amplifier under identical conditions. Using spectroscopic data as the input, amplifier gain is calculated as a function of flashlamp energy, pumping pulse duration, disk thickness, and Nd-doping. The agreement between predicted and measured gains is generally with ±10 percent, consistent with experimental uncertainties in the model and the parameters used. The operating conditions which optimize amplifier performance and efficiency for a given laser glass may be found using spectroscopic data alone. This process can be extended to derive the most cost-effective staging of amplifier chains for fusion lasers. A discussion of the model and examples of calculations are presented.

High speed, wide dynamic range analog-to-digital conversion

Abstract: A wide dynamic range, wide bandwidth, analog-to-digital conversion system and method. A plurality of overlapped analog-to-digital converters are utilized in conjunction with scaling amplifiers to provide a plurality of output ranges. Means for selecting the set of output bits which provides a magnitude representation of the input signal are provided along with means for outputting a digital representation of the appropriate range.

Theory of the Signal Transfer and Noise Properties of the rf SQUID

Abstract: The forward and reverse interactions between the SQUID input and output via the weak link are investigated in detail and presented in the form of an electronic equivalent circuit of the SQUID. The input and output impedances and the gain of the SQUID are given. The noise properties for all kinds of source impedances are computed and optimal values derived.

CCD Input circuits

Abstract: The circuits include a floating diffusion, a source supplying a controllable amount of charge to the floating diffusion and a charge coupled device (CCD) reference register for periodically removing a fixed amount of charge from the floating diffusion. A feedback circuit senses the average voltage at the floating diffusion and adjusts the controllable amount of charge supplied to the diffusion to maintain its average voltage level constant. The feedback circuit may be employed automatically to control the direct voltage bias at the input electrode of a DDC signal register. It may alternatively be employed to control a radiation source serving as the input to the system, or to operate a circuit for indicating the frequency at which the reference CCD register is being driven, or as an input to a current mirror amplifier.

Two-part current injection interferometer amplifiers and logic circuits

Abstract: Josephson junction interferometers having nonlinear switching or threshold characteristics are disclosed. The nonlinear threshold characteristic is achieved in a preferred manner by applying an injection current to the interferometer at a point on the interferometer which is different from where its gate current is normally applied. The resulting nonlinearity provides for high amplification. The nonlinear switching characteristic may also be achieved by applying an injection current to the same point on the interferometer where the gate current is normally applied. However, a portion of the thus-applied injection current is electromagnetically coupled to the interferometer inductance to achieve the desired nonlinear switching characteristic. Parameters such as the injection current, the gate current, physical point of application of the injection current to the interferometer, junction currents and the inductance of the interferometer may be changed to tailor the threshold characteristic to provide a desired nonlinearity. Logic circuits such as AND, OR and INHIBIT circuits in addition to the basic amplifier circuit are also disclosed.

Gyrotrons for high power millimeter wave generation

Abstract: The gyrotron is a new type of micrwave tube capable of producing high power output at millimeter wavelengths. Oscillator results have been described in recent Soviet publications This paper describes work in progress at Varian Associates, Inc. to develop an amplifier of the gyroklystron type to deliver 200 kW cw at 28 GHz. Considerable progress has been made with amplifier stability to the point that amplifier gains of up to 40 dB have been measured in a pulsed experimental amplifier. Current effort is concerned with improving efficiency. A pulsed oscillator is also described which produced 248 kW peak power at 28 GHz with 34% efficiency. A cw oscillator is under construction. Areas for future R and D are discussed. These include gyro-TWT amplifiers with increased instantaneous bandwidth (5 to 10%) and operation at harmonics of the cyclotron frequency to reduce the magnetic field requirements.

Amplifier with multifilter

Abstract: In an audio amplifier for amplifying signals from an electric guitar or the like having a conventional tone control circuit for selectively emphasizing input signals in the bass, middle and treble frequency ranges of the instrument, a multifilter circuit for emphasizing input signals with frequencies in selected, relatively narrow, frequency bands in the upper portion of the frequency spectrum to minimize aural fatigue. The multifilter circuit comprises a plurality of parallel connected, two-pole, resonant filter sections with different, relatively narrow, resonant frequency bands separated from one another by an amount on the order of 1/4 octave and forms a signal path that supplements the signal path provided by the conventional tone control circuit. The signals produced on the output of the tone control circuit are mixed with the multifilter output signals. Potentiometers are provided to vary the amplitude of the output signals of the entire multifilter circuit or selected ones of the filter sections thereof. Both the amplitude and phase frequency response of the multifilter are characterized by a plurality of successive peaks and dips, such that as the musician plays different notes, certain number of harmonics are emphasized in some notes, while other harmonics are emphasized in other notes with respect to amplitude while variations in the pitch or frequency of the input signal result in the phases of the individual harmonics to be rapidly shifted which causes minute shifts in the pitch of the individual harmonics produced on the output.

High speed electrostatic voltmeter

Abstract: A large bandwidth non-contacting voltage follower for detecting and following both static or d.c. and dynamic or a.c. data of an electrical field or potential being measured. A probe or sensor includes a pair of voltage sensitive electrodes which are vibrated or oscillated within a housing to vary the capacitive coupling between the electrodes and external field or potential in an inverse manner to induce signals on the electrodes having static and dynamic data from the field or potential. The signals are processed and applied to the input of a voltage follower amplifier, the output of which is coupled to the probe housing as a reference, so that the follower output follows the static and dynamic characteristics of the external field or potential.

Parametric amplification and oscillation at 36 GHz using a point‐contact Josephson junction

Abstract: We have observed doubly degenerate parametric amplification and oscillation at 36 GHz from a single point‐contact Josephson junction. The experimental results agree qualitatively with theoretical calculations based on the resistively shunted junction model. The estimated noise temperature of an amplifier with 11 dB net gain is consistent with zero, but has an upper limit of 50 K. Attempts to observe parametric amplification in the singly degenerate mode with a pump frequency of 72 GHz were not successful.

Graceful Degradation Properties of Matched N-Port Power Amplifier Combiners

Abstract: The graceful degradation properties of matched isolated power combiners as a function of amplifier failures of the same type has been determined using general techniques applicable to all such circuits. The effects of complete amplifier failures, amplitude and phase imbalances and poor VSWRs on overall combiner system output power, combining efficiency and input-output impedances can be determined by the resulting equations and plots.