Showing papers on "IMPATT diode published in 1975"

Premature collection mode in IMPATT diodes

Abstract: Experimental efficiencies of up to 35.5 percent have been reported for Read-type GaAs diodes, whereas theoretical calculations have predicted an upper limit of approximately 30 percent for the conversion efficiency of IMPATT diodes. The concept of a premature collection mode is shown to resolve this discrepancy by predicting maximum efficiencies close to 40 percent. Premature collection refers to large-signal conditions where the modulation of the drift width is sufficiently large to result in collection of the avalanche current pulse at drift angles smaller than the small-signal angle. It is shown that a discontinuous transition between the IMPATT and the premature collection modes takes place when the drift angle in the small-signal limit is greater than π. Designing the diode for close to punchthrough conditions in small-signal operation extends the practical frequency range for inducing premature collection by avoiding long drift angles and corresponding rapid conductance saturation in the IMPATT mode. The onset of premature collection is accompanied by a substantial increase in power output because of a more favorable drift angle, and in high noise because of the high RF levels involved. The jump in transit angle causes a discontinuous increase in negative conductance. The hysteresis in the tuning characteristic resulting from this discontinuity has been observed experimentally. Noise measures in the range 60-70 dB have been measured and calculated for the premature collection mode compared to 40-50 dB under large-signal conditions for the IMPATT mode. Therefore, the high efficiencies available with the premature collection mode are expected to be usable only in applications where high noise levels can be tolerated.

10-W and 12-W GaAs IMPATT's

Abstract: Hi-lo and lo-hi-lo GaAs Schottky-barrier IMPATT diodes have generated CW power outputs over 12 and 10 W, respectively, at 6 GHz. Noise measurements indicate a decreasing FM noise measure with increasing power output. The diodes are less susceptible to tuning-induced burnout than are flat-profile GaAs Impatts, having repeatedly survived input power surges over 70 W.

Noise characteristics of GaAs and Si IMPATT diodes for 50-GHz range operation

Abstract: Direct comparison of noise behaviors between GaAs Schottky-barrier junction and Si diffused p+-n junction diodes operating in the 50-GHz range is reported by using the same circuitry. In the oscillator operation, the GaAs diode exhibits excess "1/fm" noise near carrier, whereas the Si diode shows flat spectrum. Far from the carrier, and AM-DSB-NSR of -133 dB in a 100-Hz bandwidth and an FM noise measure of 27.1 dB are observed for GaAs diodes. Corresponding values obtained for Si diodes are -125 and 36.2 dB, respectively. As a reflection amplifier, minimum noise figures of 27.5 and 38 dB are achieved for the GaAs and Si devices, respectively. These results indicate that the GaAs IMPATT is superior in noise behavior to the Si diode also in the 50-GHz frequency range by about 10 dB. It is emphasized that the noise induced in the bias circuit of the IMPATT oscillator is a replica of the sideband noise of the output power and can be used as an indicator to obtain a low-noise tuning condition of the oscillator.

Microstrip Varactor-Tuned Millimeter-Wave IMPATT Diode Oscillators

Abstract: Varactor-tuned millimeter-wave IMPATT diode oscillators in microstrip form using chip-mounted diodes are described. A nearly level output power of 28 /spl plusmn/ 8 mW was achieved over a 6-GHz tuning range. Tunable bandwidths as high as 8 GHz with 6-26 mW of power were obtained from a single source. P-type epitaxial silicon IMPATT diodes were used for both the active device and the tuning varactor functions.

IMPATT oscillators with enhanced leakage current

Abstract: The behavior of IMPATT oscillators with enhanced leakage current has been experimentally evaluated by irradiating operating diodes with transient ionizing radiation. Leakage current was induced in diffused junction GaAs and silicon X-band IMPATT diodes by irradiation with 100 nsec pulses of 10 MeV electrons. With increasing leakage current, the oscillator RF power decreases and the frequency of oscillation increases. A large signal circuit model of the IMPATT diode is developed which correlates well with experimental measurements.

A mechanism for catastrophic failure of avalanche diodes

Abstract: A simple computer model of the dc electrical-thermal behavior of a Schottky-barrier GaAs IMPATT diode has been modified to include the effects of temperature-dependent thermal resistance. This has made possible the computation of dc V-I characteristics for various IMPATT diode designs and parameters. Computed terminal V-I characteristics, as well as E-J characteristics for points within the depletion layer invariably have shown successive regions of increasing, then decreasing, positive differential resistance, culminating in a region of negative differential resistance. According to an analysis of differential negative resistance appearing in the literature [5], it is a natural consequence of operation in a negative resistance region for high-current filaments to form. Furthermore, a phenomenological argument is cited to justify high-current filamentation in a region of decreasing positive resistance. Experimental evidence is advanced to support the contention that IMPATT shortouts are the natural consequence of diode operation beyond a differential resistance maximum, where the resistance, although positive, is decreasing and the formation of destructive high-current filaments is inevitable.

Thermal runaway of IMPATT diodes

Abstract: A simple one-dimensional computer model of the dc-thermal behavior of a Schottky-barrier GaAs IMPATT diode has been formulated to compute the conditions for thermal runaway in IMPATT diodes of various designs. The model has been used to determine the thermal stability conditions for three designs of GaAs IMPATT's. The computations lead to several conclusions, the most important of which are the following. a) Junction thermionic emission (leakage) current is thermally unstable, whereas avalanche multiplication is thermally stabilizing. Diode thermal stability at high junction temperature requires that the thermionic emission current be low and the avalanche multiplication be large. b) Lowering of the barrier height caused by contaminants or defects at the junction increases the likelihood of thermal runaway. c) For a given barrier height, the higher the doping of the IMPATT diode, the more resistant it will be to thermal runaway.

High−frequency limitation on silicon IMPATT diode: Velocity modulation

Abstract: The effects of the energy relaxation time on the carrier velocity in silicon semiconductor materials is considered in the millimeter wave range. For this purpose an approximate formula relating the carrier velocity evolution in large−signal operation has been derived. Its influence on the rf output power and efficiency of the silicon IMPATT oscillator is discussed. Numerical results achieved reveal that the velocity modulation is one of the fundamental effects which limit the efficiency and power delivered at high frequencies; for example, at 100 GHz it causes an efficiency diminution which can exceed 30%.

On the signal dependence of avalanche noise generation

Abstract: The influence of ionization in the drift space of an IMPATT diode on the noise generation in the avalanche process is studied It is found that carrier generation by ionization in the drift space increases the current minima between the current pulses as generated in the avalanche region The build-up of new avalanche current pulses therefore starts from a higher current level and consequently the behavior is less noisy The effect of this decrease in noise on the IMPATT-diode oscillator FM noise is estimated

A computer simulation scheme for various solid-state devices

Abstract: The main computational scheme for the determination of the device-circuit interaction and the internal dynamics of the solid-state device are described. Certain important details are separately discussed in Appendixes. A unique feature in the simulation is the boundary condition at the electrode, characterized here by an energy barrier. Formulated in this way, successful simulations of the Gunn diode, injection-controlled amplifier, IMPATT diode, TRAPATT condition, controlled-avalanche transit-time (CATT) triode, as well as other phenomena reported in the literature, have been demonstrated.

Microwave diode switch wherein first diode carries greater control signal current than second diode

Abstract: A p-i-n diode microwave switch is disclosed capable of hot switching relatively high power microwave energy while maintaining high isolation between the input and outputs. To accomplish the high isolation at high power operating levels multiple p-i-n diodes are utilized with different forward and reverse bias potentials being applied to different diodes.

Microwave solid state circuit employing a bipolar transistor structure

Abstract: This microwave circuit incorporates a transistor structure that provides either a two port amplifier or an injection frequency locked oscillator. This circuit eliminates circulators employed with Gunn and Impatt diode amplifiers and injection frequency locked oscillators. The collector-base junction is reverse biased so that the collector region functions either in the Impatt mode or in the transferred electron mode. An RF input signal is applied across the forward biased emitter-base junction. With a load across the collector-base junction having a conductance equal to the absolute value of the negative conductance generated by the collector region, the circuit functions as an oscillator at a frequency which is injection locked to the frequency of the input signal. With a load of increased conductance to suppress oscillations, i.e. overload the collector region, the circuit functions as an amplifier.

Retardation of Impatt diode aging by use of tungsten in the electrodes

Abstract: Stable rf performance of Pt‐GaAs Schottky barrier Impatt diodes may be affected by the platinum reacting with the GaAs, thereby producing junction movement during aging. This paper presents data which monitor the junction movement and then demonstrates the effect of using a tungsten layer to limit the Pt‐GaAs reaction. The tungsten layer does not alter the rf performance. The platinum ’’chew in ’’ is controlled and the tendency of the reverse I‐V characteristics to soften with age is slowed.

Invited paper. Avalanche diode oscillators. II. Capabilities and limitations.

Abstract: The previous part of this survey described the basic physics of avalanche diodes. This paper considers the optimum design of an IMPATT oscillator and reviews the properties of the conventional device. The physics of high efficiency gallium arsenide diodes is then described, and possible advances upon present designs are discussed. The limitations of avalanche diodes, in terms of power, frequency, noise and stability are then discussed in some detail. Finally the effects of material parameters on device performance are described and the properties of silicon and gallium arsenide are compared.

A simple approximate method of estimating the effect of carrier diffusion in IMPATT diodes

Abstract: Most large-signal analyses of IMPATT diodes neglect the diffusion of charge carriers in the drift region. A correction can be introduced to include the effect of diffusion in the negative conductance or the efficiency of the IMPATT diode calculated from such analyses. An approximate method of estimating a simple correction factor is presented using the Read model of the diode.

A reliable fifteen-percent-efficiency Silicon double-drift-region IMPATT diode

Abstract: This letter describes the development of a medium-power high-efficiency high-reliability double-drift-region silicon IMPATT diode intended for use in telecommunication satellites at 11-13 GHz. The design is based on large-signal computer simulations. The highest efficiency obtained is 15.1 percent. A pilot reliability test has accumulated 7700 dc device hours at 270°C with no failures. During screening, 6000 RF device hours with no failures at approximately 180°C were also noted.

Ion-Implanted Profiles for High-Frequency (> 100 GHz) Impatt Diodes

Abstract: Ion-implanted p(boron)- and n(arsenic)-type dopant profiles have been used in the fabrication of D-band double-drift-region (DDR) and single-drift-region (SDR) silicon IMPATT diodes for precise control of the impurity levels and dimensions of the space-charge and contact regions. Factors which influence the final diode designs are discussed. Continuous-wave output powers and conversion efficiencies obtained at 140 GHz are 80 mW and 2% for a DDR device and 140 mW with 2.8% for a complementary SDR didode.

Ku-band MIC GaAs IMPATT amplifier modules

Abstract: A compact (2.0 by 1.6 in), light weight (2.1 oz), microwave integrated circuit (MIC) GaAs IMPATT amplifier module having 3.6-W pulsed output power with a gain of 22.5 dB over the 9.2-9.8 GHz band has been developed for phased array radar applications. The design goal for the module was 4-W pulsed output power with 23-dB gain over this frequency band. The module has been operated over a wide range of pulse lengths (200 ns-50 /spl mu/s) and duty factors (0.5-40 percent) with outstanding pulse fidelity. The totally integrated module consists of three IMPATT reflection amplifier stages in cascade with input and output isolators and a transmit/receive switch. Each amplifier stage has an independent hybrid thin film constant current pulse modulator. The design considerations of the essential components for final module integration, and the microwave performance characteristics are presented.

Tunable oscillator/amplifier circuit for millimeter-wave diodes

Abstract: Disclosed is microwave oscillator or amplifier circuitry which is tunable over a wide bandwidth and which includes an improved variable loading on a negative resistance semiconductor diode, such as an IMPATT diode. This loading is provided in mutually perpendicular directions closely adjacent the diode. In one direction, a DC bias connection is mounted together with an adjustable coaxial filter thereon, and this filter serves as a series tuning element for the diode. A movable short is mounted for adjustment in a direction perpendicular to that of the above coaxial filter and provides parallel tuning for the diode. These series and parallel tuning elements are operative to match the real and imaginary components of the diode impedance to the real and imaginary components of the load impedance, respectively, at a particular operating frequency, thereby maximizing the power transfer and the DC to RF conversion efficiency of the circuitry. For ease of frequency adjustment, all of the frequency dependent parameters of the circuitry are contained in a removable and replaceable insert which fits securely into the waveguide housing.

High efficiency gallium arsenide impatt diodes

Abstract: The operating frequency of an IMPATT diode depends on the width of the depletion region formed during operation. The frequency of high efficiency GaAs IMPATT diodes comprising a non-uniformly doped depletion region contacted by a rectifying barrier can be more precisely fixed by forming a "clump" of charge at exactly the depth below the surface contacted by the rectifying barrier corresponding to the desired depletion region.

Controlling the amplification in a radiation detecting avalanche diode

Abstract: A method and circuit for controlling the amplification in a radiation-detecting avalanche diode in which the diode generates electrical signals dependent upon the received radiation. These electrical signals are fed to evaluating means and a control signal is derived from the diode having a frequency which differs from the frequency used in the evaluation means. The amplitude of the control signal is compared with a preset value and the supply voltage of the diode is varied in dependence upon this comparison for controlling amplification of the diode.

Beam-Lead plated heat sink GaAs IMPATT: Part I—Performance

Abstract: GaAs IMPATT devices are currently being developed for use as high-power microwave oscillators. Since low thermal impedance is required for dissipation of high input powers, this device is usually fabricated by thermal compression bonding to a diamond heat sink or a multimesa plated heat sink. This paper discusses the development of 4-mesa beam-leaded plated heat sink (BLPHS) C- and X-band GaAs IMPATT diodes. A description of the fabrication procedures is given, whereby the beam-lead interconnects are formed as part of the wafer fabrication procedure. Diodes tested at 5 GHz give up to 7.3 W of output power at 13.5- percent efficiency at a junction temperature of approximately 210°C. X-band diodes, although the data is more limited, show efficiencies up to 16.5 percent (2.2 W) for fiat profile diodes, and up to 20.8 percent for lo-hi-lo profile diodes. BLPHS diodes, therefore, are limited in their efficiency by the epitaxial material's doping profile. Accelerated stress aging data taken to date on BLPHS units show them to have an estimated mean time to failure greater than 2 × 106h at 200°C, which is comparable to thermal compression bonded to diamond units.

A 10-W 6-GHz GaAs IMPATT amplifier for microwave radio systems

Abstract: This paper will cover an IMPATT amplifier using five flat-doping-profile GaAs diodes in three cascaded, circulator-coupled stages, suitable for power amplifier use in a longhaul FM radio relay system.

The Effect of Transferred-Electron Velocity Modulation in High-Efficiency GaAs Impatt Diodes

Abstract: The transferred-electron effect on high efficiency IMPATT avalanche diodes characterized by non punch-through structures is investigated. It is shown that the high (greater that 30%) output efficiencies, experimentally obtained with GaAs non punch-through IMPATT devices, are only possible due to the specific features of the electron velocity versus electric field dependence in this material. Some experimental results are given which corroborate the theoretical conclusions. Based on this new understanding, suggestions are made for further improvement of IMPATT performance.

A 1-watt, 6-gigahertz impatt amplifier for short-haul Radio applications

Abstract: A 1-watt impatt diode amplifier has been developed for short-haul FM radio relay applications in the 6-GHz common-carrier band. The amplifier is used in the new tm-2 system and as part of a retrofit package to upgrade the performance of the existing tm-1 system. Amplification is provided by a single silicon impatt diode which is used in an injection-locked mode. A finned heat sink provides impatt diode cooling by natural air convection within the radio bay. The diode is expected to have a mean life greater than 10 years, and it can be replaced in the field without the use of special tools or equipment. This microwave-integrated amplifier contains the rf samplers and detectors necessary to monitor both input and output rf power levels. The input power monitor also provides an input to a power-supply squelch circuit that removes dc power from the impatt diode if the rf input signal level becomes too low for adequate performance. The influence of the system requirements upon the amplifier design is described, and data on system performance are presented.

Method of making impatt diode and resulting diode

Abstract: An IMPATT diode is manufactured by doping a silicon n-type epitaxial layer and bombarding the doped layer with ions, preferably protons.

Multiple diode microwave oscillator apparatus

Abstract: Novel apparatus is provided which permits the additive combination of the peak pulse power from multiple avalanche diodes operating in the IMPATT mode without spurious signal generation and includes the use of radially disposed combinations of avalanche diodes and coaxial transmission line resonators feeding a common signal output coupler.

Nonlinear Effects in Impatt Diode Amplifiers

Abstract: The nonlinear effects in Impatt diode amplifiers have been investigated both theoretically and experimentally. Output power, group delay and AM-to-PM conversion characteristics show an increased unsymmetry with enhanced input level. The FM distortion is higher at band center than at the resonant frequency. Below the band center, a maximum is reached at for the AM-to-PM conversion. The output power of an amplifier may be much higher than that of an oscillator with the same diode.

Frequency Multiplication By A P-I-N Diode When Driven Into Avalanche Breakdown

Abstract: An investigation of frequency multiplication using a step-recovery diode (SRD) driven into avalanche breakdown is presented. This mode of operation, which is called the "breakdown mode," consists of a reverse-biased p-n junction, SRD, or IMPATT diode driven into reverse breakdown by an ac signal source. As the diode voltage passes from reverse bias to reverse breakdown and avalanche, the state of the diode switches quickfy from a depletion-layer capacitance to an avalanche inductance; hence the production of strong harmonics. A theoretical analysis and experimental investigation of a coaxial/waveguide 2-6-GHz frequency multiplier using HP5082-0320 step-recovery diodes, [R/sub s/ = 0.75 Omega, C/sub d/(-6/sub v/) = 1.0 pF] shows that the breakdown-mode frequency multiplier has a higher conversion efficiency than the conventional "charge-storage" multipuer. A measured conversion efficiency of 73 percent was achieved while the same circuit configuration produced 52 percent for the same diode used as a charge-storage multiplier under optimum forward-drive and tuning conditions. Also the theory developed in this paper indicates a maximum possible conversion efficiency of 80 percent for the breakdown-mode multiplier, which corresponds closely with the measured results, and a maximum theoretical efficiency for a forward driven diode of 64 percent. The performance of an FM microwave system was monitored using the breakdown multiplier as a LO in which a baseband SNR of 59 dB was recorded.

Millimeter-wave IMPATT diodes with improved efficiency by using ion-implanted ohmic contact

Abstract: The application of arsenic ion-implantation to the reduction of the contact resistance in the n+substrate of millimeter-wave IMPATT diodes is discussed. Single-drift-region-type IMPATT fabricated with these techniques exhibited output powers ∼600 mW at ΔTj = 200°C with 8.7-percent conversion efficiencies over frequency range of 52 to 60 GHz.