DOCSLIB.ORG

California State University, Northridge Impatt Diode

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
California State University, Northridge Impatt Diode CALIFORNIA STATE UNIVERSITY, NORTHRIDGE IMPATT DIODE POWER ACCUMULATOR A thesis submitted in partial satisfaction of the requirements for the degree of Master of Science in Engineering by Steven Eugene ~amilton / June, 1979 The Thesis of Steven Eugene Hamilton is approved: Steven D. Gavazza Edmond S. Gillespie~ California State University, Northridge ii TO MY LOVING WIFE AND CHILDREN iii TABLE OF CONTENTS Page ABSTRACT ix Section I INTRODUCTION 1 Section II ACTIVE CIRCUIT DESIGN 3 Section III SINGLE DIODE WAVEGUIDE OSCILLATOR 14 Section IV HI-PAC DESIGN 20 Section V POWER COMBINER PERFORMANCE 46 Section VI CONCLUSIONS 57 REFERENCES 59 APPENDIX A DIODE CHARACTERIZATION 62 LIST OF TABLES v LIST OF FIGURES vi iv f ' LIST OF TABLES . TABLE 1 Power and Efficiency Versus Rc p4~e 2 Power and Efficiency Results 52 Al Varian Diode VSX9251 AD 99 A2 Diode Comparison 100 v LIST OF FIGURES Figure Page 1 IMPATT Diode 5 (a) Structure {b) Field Profile (c) Electron Energy (d) Voltage Wave Form (e) Injected and External Current 2 Equivalent Circuit of Diode and Load 8 (a) Diode Chip and Load (b) Packaged Diode and Load ·3 Coaxial Oscillator 10 (a) Structure {b) Equivalent Circuit 4 Design Curves for a Single Step 12 Transformer 5 Single Diode Waveguide Oscillator 15 (a) Side View (b) End View 6 Equivalent Circuit of Single Diode 17 Waveguide Oscillator 7 Kurokawa Waveguide Oscillator End View 21 8 Kurokawa Waveguide Oscillator Top View 22 9 24 Diode HiPac 24 10 Module Configuration 26 (a) Kurokawa Module (b) HiPac Module 11 Cross-Sectional View of Diode 27 12 Module Spacing for HiPac 29 13 Waveguide TE011 Mode Cavity 31 14 Power Versus Current for Different 36 Circuit Load vi Figure pjge 15 Equivalent Circuit of HiPac 16 Power and Efficiency Versus Current 40 for Rc < Ropt 17 Power and Efficiency Versus Current 41 for Rc = Ropt 18 Power and Efficiency Versus Current 42 for Rc > Ropt 19 IMPATT Oscillator Test Set-up 45 20 Assembled End View of HiPac 47 21 Disassembled View of HiPac 48 22 Power and Efficiency Versus Current 49 8 Diodes in HiPac 23 Comparison of HiPac Performance to so Eight Times Single Diode Data 24 Power and Efficiency Versus Current 53 4 Diodes in HiPac 25 Power and Efficiency Versus Current 54 2 Diodes in HiPac 26 Mechanical Tuning Bandwidth of HiPac 56 Al Low-High-Low Diode 64 (a) Doping Profile (b) Electric Field A2 Hie;h-Low Diode 65 (a) Doping Profile (b) Electric Field A3 Cross Section of High-Low Diode 66 A4 High-Low Diode 67 (a) Layer Definition (b) Electric Field AS Mean Life to Failure 76 A6 Cross-Sectional View of Diode 78 A7 Doping Profile of High-Low Diode 82 vii Figure AB C-V Plot of High-Low Diode PB~e A9 Equivalent Circuit of Packaged Diode 90 AlO Equivalent Circuit of the Packaged 92 Diode and Load Reactance viii ABSTRACT IMPATT DIODE POWER ACCUMULATOR by Steven Eugene Hamilton Master of Science in Engineering This thesis presents the development of a new type of I~ATT diode power accumulator. The design has twice the capacity of similar accumulators of the same size. The circuit offers high combining efficiency, reduced thermal interaction and broad tuning bandwidth. The basic concepts of IMPATT oscillators are dis­ cussed. A single diode version of the power accumulator is presented in detail along with an equivalent circuit. A technique to optimize IMPATT oscillators is covered with experimental verification. The power combiner performance is demonstrated utilizing 2, 4 and 8 diodes. The broad tuning bandwidth of the combiner is presented for the eight diode configuration only. The optimum performance of a power combiner is attained when all the diodes, to be combined, have similar characteristics. To achieve the optimum condition, a ix technique is presented which determines if the diodes are suitable for combiner application. X SECTION I INTRODUCTION The development of solid state microwave sources has experienced tremendous growth over the past ten years. Their high reliability, low cost and small volume are characteristics which attract many designers. Solid state sources have been developed for communications, space and radar systems to replace low and medium power tube type transmitters. The principal devices responsible for solid state growth have been FETs and IMPATTs*. These devices have all served as the fundamental building blocks in the new solid state components. Within the past six years the IMPATT diode has clearly set the pace for solid state technology by replacing several tube type transmitters. This has been accomplished by the development of many new devices and power combining circuits. Recently, improvements in combiner power level have been attained only through the development of higher power diodes. This presents a problem to the solid state design­ er in that future requirements will exceed the capability * FET is an acronym for Field Effect Transistor. IMPATT is an acronym for Impact and Transit Time Device. 1 ~'· 2 of present combining techniques. To maintain their growth, solid state designers have resorted to utilizing circuits which can potentially meet future requirements by combining larger numbers of diodes; unfortunately, the new circuits operate at reduced efficiency, require increased fabrica­ tion cost and exhibit reduced reliability. The aforemen­ tioned characteristics reduce the advantages that solid state sources have over other transmitter technologies. It is the object of this thesis to reclaim some of the desirable characteristics of solid state sources and, in addition, to satisfy future power requirements. To accom­ plish this task, a new combining technique has been developed which is capable of summing more devices than was previously attainable. This technique offers high combin­ ing efficiency and greater reliability than other designs. In order to demonstrate the new combiner circuit, three oscillators were designed and fabricated. The design utilizes a waveguide cavity with a plurality of coaxial modules located along the cavity walls. IMPATT diodes are located at one end of a coaxial transmission line with a bias filter at the other end. The test results are presented both in tabular and graphical form to illustrate the circuits capability and to compare its performance against previously developed technology. A simple model will be presented to discuss the various characteristics of the new circuits, hereafter referred to as HiPac. ~·· SECTION II ACTIVE CIRCUIT DESIGN A. Introduction The design of an active circuit utilizing negative resistance devices is a complicated process. The param­ eters which must be considered involve areas of semi­ conductor physics and standard microwave circuit technol­ ogy. Unfortunately, the non-linearity of the device, which makes it useful, also prevents closed form solutions in large signal analysis. In addition, as one strives for high power sources, devices are typically combined in complex microwave circuits. These circuits usually have mutual coupling interactions which are as equally difficult to analyze as the active device. In this section, several aspects of the design will be presented, although only those subjects pertinent to the design process will be discussed. Approximations and limits will be presented as required, and more detailed studies will be referenced. B. IMPATT Diode The type of device used in this study is a gallium arsenide IMPATT [1] [2]. The GaAs IMPATT is the highest efficiency device in the IMPATT family [3] [4]. Silicon 3 4 and indium phosphide materials are also used in construct­ ing IMPATT diodes; but they operate at half the efficiency of GaAs. As previously stated, the IMPATT diode is a negative resistance device. The negative resistance occurs as a result of a 180° phase difference which is developed be­ tween the ac current and voltage within the device. The diode is essentially composed of two constituents: (1) the avalanche zone and (2) the drift zone (also known as depletion zone). Consider the simple P+N N+ diode shown in Figure la, with reverse bias applied as indicated. Within the diode, an electric field profile, as shown in Figure lb, is developed. The high field, which exists between x1 and x2 , establishes the avalanche zone. In this region avalanche breakdown occurs which generates hole electron pairs. The region between x2 and x3 is called the drift zone, where the field is high enough to maintain constant drift velocity but not high enough for avalanche to occur. Figure lc shows the energy band diagram under breakdown conditions. The holes generated in the avalanche zone go into the p+ region while the electrons are injected into the N region, drift zone. If an ac voltage, as shown in Figure ld, is applied to the diode, via noise or some other stimulus, the electric field will change periodically with time around some average value. The rate of impact ionization will follow the change in field almost 5 14--- DRIFTZONE ~ p+ N N+ -1 I i I ~+ ~~-- AVALANCHE ZONE (a) Structure ELECTRIC FIELD ~ p+ I N N+ I I X x 1 x 2 x3 DISTANCE (b) Field Profile ELECTRON ENERGY DISTANCE (c) Electron Energy AC VOLTAGE 8 = Wt (d) Voltage Wave Form CURRENT T 2T (e) Injected and External Currents Figure 1. lmpatt Diode 6 instantaneously. However, the carrier density does not follow the field change in unison because the generation of carriers depends on the number already generated. So when the field is maximum, carrier generation is still increas­ ing and does not peak until after the field has decreased by some amount. Thus we have the carrier density peak lagging the ac voltage by about 90° (see Figure ld and le). The injected electrons then enter the drift zone where, because of the field, they travel at a saturated or scattering-limited velocity.
Load more

Recommended publications
  • Book of ABSTRACTS
    Proceedings of the International Conference “Micro- and Nanoelectronics – 2016” with the Extended Session Book of ABSTRACTS October 3 – 7, 2016 Moscow – Zvenigorod, Russia RUSSIAN ACADEMY OF SCIENCES FEDERAL AGENCY OF SCIENTIFIC ORGANISATIONS INSTITUTE OF PHYSICS AND TECHNOLOGY Proceedings of the International Conference «Micro- and Nanoelectronics – 2016» ICMNE – 2016 Book of Abstracts October 3–7, 2016 Moscow – Zvenigorod, Russia MOSCOW – 2016 УДК 621 ББК 32.85 М59 Издание осуществлено при поддержке Российского фонда фундаментальных исследований по проекту 16-07-20515 Под редакцией: чл.-корр. РАН В.Ф. Лукичева; д.ф.-м.н. К.В. Руденко Составитель к.ф.-м.н. В.П. Кудря Микро- и наноэлектроника – 2016: Труды международной конфе- М59 ренции (3–7 октября, 2016, г. Звенигород, РФ): Сборник тезисов / Под ред. В.Ф. Лукичева, К.В. Руденко. Составитель В.П. Кудря. – М.: МАКС Пресс, 2016. – 234 с. ISBN 978-5-317-05369-7 Сборник содержит тезисы докладов, представленных на Международной конфе- ренции «Микро- и наноэлектроника – 2016» (ICMNE-2016), включающая расширен- ную сессию «Квантовая информатика» (QI-2016). Тематика конференции охватыва- етбольшинство областей физики микро- и наноразмерных приборов, а также микро- и наноэлектронных технологий, и концентрируется на освещении последних достиже- ний в этой сфере. Она продолжает серию всероссийских (с 1994 года) и международ- ных конференций (с 2003 года). Ключевые слова: нанотранзисторы, затворные стеки, квантовые компьютеры, МЭМС, магнитные материалы, оптоэлектроника. УДК 621 ББК 32.85 Publishing was supported by Russian Foundation for Fundamental Research, project 16-07-20515 Micro- and Nanoelectronics – 2016: Proceedings of the International Confe- rence (October 3–7, 2016, Zvenigorod, Russia): Book of Abstracts / Ed. by V.F. Lukichev and K.V.
    [Show full text]
  • Sub-Terahertz: Generation and Detection
    Sub-Terahertz: Generation and Detection Mohd Azlishah bin Othman, MSc. Thesis submitted to University of Nottingham for the degree of Doctor of Philosophy June 2013 Acknowledgment I would like to express the deepest appreciation to my supervisor, Professor Dr Ian Harrison, for his guidance throughout my research work. For Ian, it is your brilliant insights and support that make this work possible and I owe you so much not only for your support on the research, but also for your support in my life. Furthermore, thanks to all research staff in Photonic and RF Engineering Group under Division of Electrical Systems and Optics, Department of Electrical and Electronic Engineering, University of Nottingham for their support and cooperation on the work. Besides, I would like to express my deepest gratitude to the rest of colleagues, technicians, my fellow labmates in University of Nottingham: Xiao Li, Suhaila Ishak, Leah Righway, Vinoth, Frank, Kuldip and Fen for all the fun we had in the last four years. Special thanks are owed to my parents and sisters, whose have supported me throughout my years of education, both morally and financially, and the one above all of us, the supreme God, for answering my prayers. Also, thanks a lot to my beloved wife Shadia Suhaimi for her passion in understanding me on working for this research. Last but not least, my sincere thanks go to my sponsors; Malaysian Government and Universiti Teknikal Malaysia Melaka (UTeM), Nottingham Malaysian Community (NMC), friends and ex-housemates; Fairul Ezwan, Muzahar, Ahmad Fikri Dr. Mohd Fadzelly and Ir. Dr Nazri Othman.They were always supporting and encouraging me with their best wishes.
    [Show full text]
  • Noise in Avalanche Transit-Time Devices
    1674 PROCEEDINGS OF THE IEEE, VOL. 59, NO. 12, DECEMBER 1971 for receiving arrays,” ZEEE Trans. Antennas Propagat. (Commun.), [22] C. J. Drane, Jr., and J. F. McIlvenna, “Gain maximization and VO~.AP-14, NOV.1966, pp. 792-794. controlled null placement simultaneously achievedin aerial array [9] A. I. Uzkov, ‘‘An approach to the problem of optimum directive patterns,” Air Force Cambridge Res. Labs., Bedford,Mass., antenna design,” C. R. Acad. Sci. USSR., vol. 35, 1946, p. 35. Rep. AFCRL-69-0257, June 1969. [lo] A. Bloch, R. G. Medhurst, and S. D. Pool, “A new approach to [23] R. F. Hamngton, “Matrixmethods for field problems,” Proc. the design of superdirective aerial arrays,” Proc. Znst. Elec. Eng., ZEEE, vol. 55, Feb. 1967, pp. 136-149. VO~.100, Sept. 1953, pp. 303-314. [24] J. A. Cummins,“Analysis of a circulararray of antennas by [ll] M.Uzsoky and L. Solymar,“Theory of superdirectivelinear matrix methods,” Ph.D. dissertation, Elec. Eng. Dept., Syracuse arrays,” Acta Phys. (Budapt), vol. 6, 1956, pp. 185-204. University, Syracuse,N. Y., Dec. 1968. [12] C. T. Tai, “The optimum directivity of uniformly spaced broad- [25] B. J. Strait and K. Hirasawa, “On radiation and scattering from sidearrays ofdipoles,” ZEEE Trans. Antennas Propgat., vol. arrays of wire antennas,” Proc. Nut. Elec. Con$, vol. 25, 1969. AP-12, July 1964, pp. 447-454. [26] A.T. Adams and B. J. Strait, “Modernanalysis methods for [13] D. K. Cheng and F. I. Tseng, “Gain optimization for arbitrary EMC,” ZEEEIEMC Symp. Rec., July 1970, pp. 383-393. antenna arrays,’’ ZEEE Trans.
    [Show full text]
  • Injection Locked Gunn Diode Oscillators Phase Locked Oscillators
    Injection Locked Gunn Diode Oscillators Phase Locked Oscillators Bulletin No. OGI Bulletin No. OPL FEATURES FEATURES High output power High output power Moderate gain and bandwidth Low phase noise CW operation Internal or external reference Frequency up to 110 GHz Frequency up to 110 GHz APPLICATIONS APPLICATIONS Power amplification Local oscillators Instrumentation Multiplier drivers Local oscillators Subsystems Subsystems OGI Series 5 DESCRIPTION OPL Series DESCRIPTION OGI series CW injection-locked Gunn oscillators are alternatives to HEMT device and IMPATT diode based stable amplifiers, especially at high millimeterwave frequencies. The operating frequency and power output of these oscillators OPL series phase-locked oscillators are offered to cover frequency range up to 110 GHz by utilizing high performance are up to 110 GHz and 24 dBm. The spectrum purity of the output signal is injected signal dependent. There is an output FET oscillators, Gunn oscillators or multiplier/amplifier chain to produce desired frequency and power output. The free running signal in the absence of an input injection signal. The oscillators are provided with integral circulators and phase locked oscillators are offered with either internal or external referenced version. The phase noise of an externally optional DC voltage regulator. An optional heater is provided to achieve better temperature stability. For higher gain, referenced phase locked oscillator is depended on the quality of the reference signal. broader locking bandwidth and higher
    [Show full text]
  • Lateral IMPATT Diodes in Standard CMOS Technology
    Lateral IMPATT Diodes in Standard CMOS Technology Tala1 Al-Attar, Michael D. Mulligan and Thomas H. Lee Center for Integrated Systems, Stanford University Stanford, CA, USA Abstract An IMPATT is biased into reverse breakdown, and a frequency-dependent negative resistance arises from We investigate the use of a lateral IMPAT? diode phase delay between the current and voltage built in 0.25" CMOS technology as a high frequency waveforms in the device. power source. These diodes are monolithically Maximum output power is facilitated by arranging integrated in coplanar waveguides and characterized by for V and I to he out of phase with one another by an S-parameter measurements from 40 MHz to 110 GHz. angle of 180". The first 90" of phase shift is achieved These measurements show excellent agreement with within the avalanche region. The remaining 90" is predictions of theoretical models. To our knowledge, obtained by adjusting the drift region length. this is the first such structure built in a standard CMOS technology. Device Structure and Properties Introduction There is presently significant interest in For our design, the p', n, and n' regions of the developing low cost millimeter-wave systems for IMPATT diode (Fig. I) are implemented using applications ranging from communications to standard source/drain, n-well, and ohmic contact automobile anti-collision radar systems. CMOS diffusion regions, respectively. The dimensions of the technologies are particularly appealing from a cost diode tested (0.5pn x 100pm) are based on two : reduction and systems integration standpoint. considerations: (I) reducing the resistance of the However, these systems typically operate at inactive region by increasing the diode width while frequencies beyond currently achievable CMOS also keeping it helow a qumer wavelength to minimize transistor fT, rendering conventional CMOS circuit any resonance or phasing problems, and (2) increasing techniques useless.
    [Show full text]
  • Noise in IMPATT-Diode Oscillators
    Noise in IMPATT-diode oscillators Citation for published version (APA): Goedbloed, J. J. (1973). Noise in IMPATT-diode oscillators. Technische Hogeschool Eindhoven. https://doi.org/10.6100/IR106076 DOI: 10.6100/IR106076 Document status and date: Published: 01/01/1973 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. People interested in the research are advised to contact the author for the final version of the publication, or visit the DOI to the publisher's website. • The final author version and the galley proof are versions of the publication after peer review. • The final published version features the final layout of the paper including the volume, issue and page numbers. Link to publication General rights Copyright and moral rights for the publications made accessible in the public portal are retained by the authors and/or other copyright owners and it is a condition of accessing publications that users recognise and abide by the legal requirements associated with these rights. • Users may download and print one copy of any publication from the public portal for the purpose of private study or research. • You may not further distribute the material or use it for any profit-making activity or commercial gain • You may freely distribute the URL identifying the publication in the public portal.
    [Show full text]
  • Unit-VII Microwave Engineering
    Unit-VII Microwave Engineering UNIT-VII MICROWAVE SOLID STATE DEVICES Introduction Even though in the earlier stages of development of microwave technology, it was the tubes that played a key role, in later stages it is the semiconductor or solid state source that took the lead. The development of semiconductor technology in general helped in fabricating low voltage operated and miniaturized solid state sources at a low cost. With the advent of microwave solid state devices, the microwave applications in the area of consumer electronics rapidly expanded. The solid state sources are claimed of the advantages of longer life, requiring low voltages, easy control of amplitude of the transmitted wave form, wider bandwidths, low production costs and air cooling. In this chapter, the basic principles of functioning of Gunn diodes are first explained. Different modes of operation and theories explaining their behavior are then discussed. IMPATT and TRAPATT diodes are used to design microwave amplifiers and oscillators. Their function and design aspects are then explained. Tunnel diodes, varactor diodes are introduced and the theory of their functioning is illustrated parametric amplifies and tunnel diode amplifiers are then discussed. The chapter is concluded with a discussion on detector diodes. GUNN DIODES Gunn oscillators and amplifiers are most important microwave devices that have been extensively used as a local oscillators and power amplifiers covering the frequency range of 1 to 100 GHz in which Gunn diode is a critical part. Gunn diode is an n-type semi-conductor slab of one of the compounds, namely Ga As (Figure 7.1), InP, InAs, InSb and CdTd.
    [Show full text]
  • Assignment VI (Active Devices)
    Assignment VI (Active Devices) Tick the most appropriate answer. All symbols have their usual meaning. 1. The following device involves only one type of charge carriers a. HEMT b. Gunn Diode c. MOSFET, d. all of these. Ans: d. all of these. 2. The device also known as Transfer Electron Device (TED) is/are a. Tunnel Diode b. Gunn diode c. IMPATT diode d. All of these Ans: b. Gunn diode 3. The following source can provide high power at millimeter wave frequencies. a. Gyrotron b. Magnetron, c. Klystron d. TWT Ans: a. Gyrotron 4. PHEMT is popular for their a. high power handling capability b. low power consumption c. higher carrier velocity d. high efficiency Ans: c. higher carrier velocity 5. PIN diode can be used in application of — a. switch b. modulators, c. phase shifter d. All of these Ans: d. All of these 6. How to improve fT of a BJT— a. Decreasing base width, b. increasing doping concentration in base and using hetero junctions c. increasing electron mobility, d. all of these Ans: d. all of these 7. The reverse recovery time for an ideal Schottky diode is a. infinite b. a few µs, c. zero d. depends on manufacturing process. Ans: c. zero 8. Schottky diode is an example of a. slow recombination device, b. hot carrier device, c. step-recovery diodes, d. none of these Ans: b. hot carrier device 9. The following device can be used in a tuning circuit. a. Schottky diode b. Gunn diode, c. Varactor d. IMPATT diode Ans: c.
    [Show full text]
  • Dynamic Characterization and Noise Analysis of 4H-Sic Impatt Diode at Ka Band
    International Journal of Soft Computing and Engineering (IJSCE) ISSN: 2231-2307, Volume-4, Issue-1, March 2014 Dynamic Characterization and Noise Analysis of 4H-SiC Impatt Diode at Ka Band Joydeep Sengupta, Girish Chandra Ghivela, Monojit Mitra Abstract--The microwave as well as the small signal noise properties on a one dimensional n+npp+ DDR structure 4H-SiC IMPATT Diode have been studied using advanced computer simulation program developed by us and compared at different 82 frequency of Ka band by taking the area of the diode as 10 m . Also the theory for the diode current noise associated with the electron hole pair generation and recombination in the space charge region of the diode is presented. This paper can help to know about the small signal behavior as well as noise behavior of IMPATT diode along with power density at the Ka band and will be helpful for designing the 4H-SiC based IMPATT diode depending upon the microwave applications. Index Terms--Impact ionization, efficiency, mean square noise voltage, quality factor, noise spectral density, power density, noise measure. I. INTRODUCTION Figure1:The Active Layers of a Reverse Biased p-n Junction In recent years, IMPATT(Impact Avalanche and Transit Time) diodes have proved as a major source of microwave 1 DC ANALYSIS and millimetre wave power generator. Thus, designers are concentrating on the best semiconductor materials for the To obtain the DC parameters such as break down voltage, optimized design of the diode. For our design, we have carrier current profiles, electric field profiles etc., dc analysis choose 4H-SiC material for the IMPATT because of high is done here by solving Poisson equation, the space charge electron mobility and have recently been established as equation and the carrier continuity equation simultaneously technologically important materials for both electronic and over the double drift structure of the diode[5].
    [Show full text]
  • A Noise Reduction Design for IMPATT Oscillators
    The noise generator was a 0.005” diametermesa structurep+ nn4 silicon diode. The p-k material was formed by diffusing boron 3 microns into the n region and the p~timpurity density was approximately lOI9 per cm3. The n material, epitaxially grown on a heavily doped substrate, was approxi- matelyfour microns in thickness with animpurity density of 10’ percm3 10.5 21 cm). The crystal was mounted in a standard IN23 cartridge and tested in modifiedX-band crystal detector mounts. Noise measurements in a crystal holder with anadjustable short to op- timize the noise output and with a matched termination in place of the short are presented, The results indicate that the diode itself is an inherently broad band noise sourceand that the circuitlargely determines the bandwidth of the noise source. The results of both continuously and pulse operated diodes will be pre- sented. Note: Sponsored by Cayuga Associates, Ithaca, N. Y. I Val’d-Perlov,Krasilov, and Tager, “The Avalancing Transit-Time Diode- A New SemiconductorMicrowave Device,” Radio Engineering and Electron Physics (U.S.S.R.) No. 11, pp. 1764-1779, November 1966. 7.4 ANOISE REDUCTION DESIGN FOR IMPATT OSCILLATORS, E. J. Cook, Varian Associates, Beverly,Mass. This paper describes atechnique for achieving considerably lower noise figures for IMPATT oscillatorsthan have beenpreviously reported. With thesedevices used as local oscillators,receiver noise figures in X band within 10 dB (singleended mixer, 30 mcIF) and 0.2 dB(balanced mixer, 30 mc IF) of those produced with a klystronlocal oscillator have been ob- tained. Thetechnique alsoresults in a low oscillatorpushing figureand an accompanyingimprovement in thespectrum of the device when pulsed.
    [Show full text]
  • 1.1 Avalanche Transit Time Devices
    UNIT IV MICROWAVE SEMICONDUCTOR DEVICES AND INTEGRATED CIRCUITS Avalanche Transit Time Devices- principle of operation and characteristics of IMPATT and TRAPATT diodes, Point Contact Diodes, Schottky Barrier Diodes, Parametric Devices, Detectors and Mixers.Monolithic Microwave Integrated Circuits (MMIC), MIC materials- substrate, conductors and dielectric materials. Types of MICs, hybrid MICs (HMIC). 1.1 Avalanche Transit Time Devices Semiconductor Microwave Devices Like conventional ordinary vacuum tubes cannot be used at high frequency, because some parameters generate complicated situations and these parameters are 1. The interelectrode capacitance effect 2. The Lead inductance effect 3.Transit time To overcome the above problems one should use either a high frequency transistor or some other special type of semiconductor devices. Like negative resistance and non-linearity in the operation make these special devices (i.e. like Varactor diode, PIN diode, IMPATT diode, TRAPATT diode, Tunnel diode and Gunn diode along with the high frequency transistors) suitable for their operations in the microwave region. Some observations we conclude that Bulk semiconductor device- Gunn diode Ordinary p-n junction diodes- Varactor and Tunnel diodes Modified p-n junction diodes- IMPATT, TRAPATT, PIN diodes such as p+-n or p-i-n type Microwave semiconductor devices have been developed for various applications like, detection, mixing, frequency multiplications, attenuation, switching, limiting, amplification or oscillation etc. Advantages of these devices
    [Show full text]
  • Battery Life and How to Improve It
    Battery Life and How To Improve It Battery and Energy Technologies Technologies Battery Life (and Death) Low Power Cells High Power Cells For product designers, an understanding of the factors affecting battery life is vitally important for managing both product Chargers & Charging performance and warranty liabilities particularly with high cost, high power batteries. Offer too low a warranty period and you won't Battery Management sell any batteries/products. Overestimate the battery lifetime and you could lose a fortune. Battery Testing Cell Chemistries FAQ That batteries have a finite life is due to occurrence of the unwanted chemical or physical changes to, or the loss of, the active materials of which Free Report they are made. Otherwise they would last indefinitely. These changes are usually irreversible and they affect the electrical performance of the cell. Buying Batteries in China Battery life can usually only be extended by preventing or reducing the cause of the unwanted parasitic chemical effects which occur in the cells. Choosing a Battery Some ways of improving battery life and hence reliability are considered below. How to Specify Batteries Battery cycle life is defined as the number of complete charge - discharge cycles a battery can perform before its nominal capacity falls below Sponsors 80% of its initial rated capacity. Lifetimes of 500 to 1200 cycles are typical. The actual ageing process results in a gradual reduction in capacity over time. When a cell reaches its specified lifetime it does not stop working suddenly. The ageing process continues at the same rate as before so that a cell whose capacity had fallen to 80% after 1000 cycles will probably continue working to perhaps 2000 cycles when its effective capacity will have fallen to 60% of its original capacity.
    [Show full text]