DOCSLIB.ORG

Vmari'z'n Greenspan

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

June 13, 1957 M. GREENSPAN ErAL 2,796,522 CRYSTAL-CONTROLLED RELAXATION OSCILLATOR Filed Aug. 21, 1953 INVENTOR vMari‘z'n Greenspan M v .r I Carroll E. Ybc/u'eyy - - - Y .BY ’ AGENT , , 2,796,522 United States a atent {C Nice Patented June 18, 1957 1 2 1It is another object of the present invention to provide 2,796,522 a crystal controlled relaxation oscillator, the output of which is relatively insensitive to variations in circuit CRYSTAL-CONTROLLED RELAXATION parameters even at high division ratios. OSCELLATOR *It is another object of the present invention to pro Martin Greenspan and Carroll E. Tschiegg, Silver Spring, vide a relaxation oscillator in which the voltages along Md, assignors to the United States of America as rep the ?at portion of the capacitor discharge curve are made resented by the Secretary of Commerce to vary considerably from instant to instant. Application August 21, 1953, Serial No. 375,841 1It is another object of the present invention to pro 10 vide a relaxation oscillator in which an oscillatory volt 4 Claims. (Cl. 250—36) age with a constantly increasing amplitude is superim (Granted under Title 35, U. S. Code (-1952), see. 266) posed on the grid voltage of the oscillator tube or tubes. Further provision is also made to crystal stabilize the frequency of this oscillatory voltage. The invention described herein may be manufactured 15 and used by or for the Government of the United States 'It is a'further object of the present invention to in for governmental purposes without the payment to us of crease the frequency stability of relaxation oscillators any royalty thereon in accordance with the provisions of when working along the steep portion of the timing wave 35 United States Code (1952) section 266. form. It is another object of the present invention to pro The present invention relates to relaxation oscillators 20 and in particular to a method and apparatus for stabiliz vide a multivibrator in which the various phases of an ing the frequency of relaxation oscillators ‘by means of asymmetrical output wave are locked in by a piezoelec a piezoelectric crystal. trical crystal. ‘In the prior art numerous attempts have been made In accordance with the preferred embodiment of the to stabilize the frequency of various types of relaxation 25 present invention there is provided a multivibrator, the oscillators. in the case of the ‘blocking oscillator, Mar’ output frequency of which is synchronized with a har rison, Patent No. 1,919,795, provides a crystal-stabiliz monic or subharmonic of a piezoelectric crystal. The ing circuit. However, since the division ratios obtain piezoelectric crystal is coupled into the grid circuit of able with this circuit were rather small and the range the multivibrator, the crystal and the tube acting as a of frequencies limited, the circuit was not widely used. 30 crystal oscillator immediately prior to the ?ring of the In the case of multivibrators, which are inherently fre tube in whose grid circuit the crystal is coupled. In addi quency ‘unstable, stability has been provided by syn tion to the crystal oscillator the circuit resonates as a chronizing the frequency by means of an oscillatory volt low-Q amplitude-unstable oscillator, whose frequency is age coupled into the circuit from an external oscillator. locked on some harmonic or subharmon‘ic of the crystal The use of an external oscillator of necessity increased 35 frequency. Because the low-Q oscillator is amplitude the complexity of the circuits. unstable, successive oscillations of this circuit will pro The primary cause of frequency instability of relaxa duce output voltages of increasing amplitude, the ?ring of tion oscillators arises from the fact that the time of ?r the tubes of the multivibrator being controlled by one of ing of the oscillator tube is controlled by the rate of these voltage peaks. Since the amplitude of these peaks discharge of a capacitor in the grid circuit of the tube. is increasing rapidly, particularly during the period just As long as the ?ring of the tube takes place at a voltage before ?ring, the circuit can easily differentiate between which lies along the steep portion of the discharge curve, successive voltage peaks. the frequency stability is acceptable. However, if the Other uses ‘and advantages of the invention will be frequency is varied so that ?ring of the oscillator tube come apparent upon reference to the speci?cation and is to occur at a voltage which lies along the ?at portion 45 drawings. of the discharge curve, the frequency stability becomes {Figure 1 is a circuit diagram of a crystal-controlled very poor. ,This is due to the fact that along the ?at ‘blocking oscillator. portion of the discharge curve the variation in voltage Figure 2 is a series'of reproductions of pictures taken from instant to instant is almost in?nitesimal. In order from the face of a cathode-ray-oscilloscope, showing the ‘for a tube to ?re at exactly the same potential during 50 various wave forms obtained on the grid of the oscillator each cycle and therefore at the same time the tube tube. characteristics would have to remain just about constant Figure 3 is a circuit diagram of a multivibrator which which, of course, is impossible. is crystal controlled. -It is the primary object of the present invention to Figure 4 is a reproduction of pictures taken from the provide a simple method of and apparatus for crystal 55 face of a cathode-ray-oscillo'scope, showing the wave stabilizing the frequency of various types of relaxation form at the output of the multivibrator. oscillators. %It should be noted that the use of a crystal to stabilize It is another object of the present invention to provide rblocking oscillators is not speci?cally claimed in this appli for crystal stabilization of relaxation oscillators having cation, but the explanation of that circuit is included for high division ratios. the purpose of developing the overall concepts involved. it is another object of the present invention to pro The crystal~controlled .blocking oscillator is speci?cally vide crystal-controlled relaxation oscillators in which the claimed in co-pending application No. 376,770, ?led on frequency of the oscillator is synchronized with the fre August 26, 1953, by Moody C. Thompson, Jr., now quency of the crystal. U. S. Patent 2,761,971. ‘It is another object of the present invention to provide 65 Referring to Figure 1, the tube 11 has its cathode 12 crystal-controlled multivibrators in which the frequency grounded and its plate 13 connected through one wind of the oscillator is synchronized with the frequency of ing 14 of the pulse transformer 16 to the B+ supply. the crystal. ' The grid 17 of the tube is connected through another Another object of the present invention is to provide winding 18 of the pulse transformer and through the crystal-controlled relaxation oscillator-s which require 70 variable capacitor 19 to ground. The capacitor 19 is only very minor modi?cations of the conventional oscil shunted by the ?xed capacitor 21 and the series combina lator circuit. ‘ ’ ' tion of the ?xed resistor 22 and variable resistor 23. A 2,790,522 3 4 third winding '24 of the transformer 16 has one terminal 2. The overall shape of the wave is controlled by the dis connected to ground and the other terminal connected charge or exponential curve of the capacitor. Superposed through the crystal 26 to ground. on the capacitor-discharge Wave is the characteristic fre Assuming initially that the blocking oscillator has just quency voltage of the low-Q oscillator (curve 1‘) which, as ?red, the grid 17 is instantaneously driven very highly can be seen, builds up cycle by cycle. The curve g rep positive and then very sharply negative. The negative resents the grid potential at which the tube will ?re, there bias on the grid shuts oif the tube, and this negative charge by producing an output pulse from the blocking oscillator. is stored in the capacitors 19 and 21, thereby maintaining It will be noted that the magnitude of each positive peak, the tube in the biased-off condition. However, the such as h and 1', increases considerably over the prior posi capacitors gradually discharge through the resistors 22 10 tive peak and therefore makes it possible to differentiate and 23, and the potential on the grid 17 rises along the between one pulse and the next succeeding or prior pulse exponential discharge curve of the capacitors. When even when operating on the ?at portion of the timing wave the grid has reached a potential at which the tube can form. again ?re, a large pulse is given out by the oscillator, The frequency of the blocking oscillator is’ controlled by the grid again being instantaneously driven very highly 15 varying the discharge time of the capacitor 19. Rough positive and then very highly negative. Owing to the adjustments may be made by varying the value of resistor very tight coupling of the pulse transformer the crystal 23. This oscillator was found to have a high degree of ‘and tube combine to form an oscillator which will oscil frequency stability at even large division ratios. late for a brief period before the ?ring of the blocking It will be noted in the above analysis that several volt oscillator. Initially the crystal is caused to ring as the ages are applied to the grid-to-cathoclecircuit of the tube. result of the large output pulse supplied to it but since These voltages include a crystal oscillator voltage and a the tube is biased almostto cutoff by the large negative low-Q oscillator voltage, both of which appear in the charge stored across the capacitors 19 and 21, thetube aforementioned grid-to-cathode circuit.
Recommended publications
  • Spectrum Analyzer Circuits 062-1055-00

    Spectrum Analyzer Circuits 062-1055-00

    Circuit Concepts BOOKS IN THIS SERIES: Circuit Concepts Power Supply Circuits 062-0888-01 Oscilloscope Cathode-Ray Tubes 062-0852-01 Storage Cathode-Ray Tubes and Circuits 062-0861-01 Television Waveform Processing Circuits 062-0955-00 Digital Concepts 062-1030-00 Spectrum Analyzer Circuits 062-1055-00 Oscilloscope Trigger Circuits 062-1056-00 Sweep Generator Circuits 062-1098-00 Measurement Concepts Information Display Concepts 062-1005-00 Semiconductor Devices 062-1009-00 Television System Measurements 062-1064-00 Spectrum Analyzer Measurements 062-1070-00 Engine Analysis 062-1074-00 Automated Testing Systems 062-1106-00 SPECTRUM ANALYZER CIRCUITS BY MORRIS ENGELSON Significant Contributions by GORDON LONG WILL MARSH CIRCUIT CONCEPTS FIRST EDITION, SECOND PRINTING, AUGUST 1969 062-1055-00 ©TEKTRONIX, INC.; 1969 BEAVERTON, OREGON 97005 ALL RIGHTS RESERVED CONTENTS 1 BACKGROUND MATERIAL 1 2 COMPONENTS AND SUBASSEMBLIES 23 3 FILTERS 55 4 AMPLI FI'ERS 83 5 MIXERS 99 6 OSCILLATORS 121 7 RF ATTENNATORS 157 BIBLIOGRAPHY 171 INDEX 175 1 BACKGROUND MATERIAL Many spectrum analyzer circuits are based on principles with which most engineers may not be familiar. It is the purpose of this chapter to review some of this specialized background material. This review is not intended to be either complete or rigorous. Those desiring a more complete discussion are referred to the basic references and the bibliography. TRANSMISSION LINES* At low frequencies the basic circuit elements are lumped. At higher frequencies, however, where the size of circuit elements is comparable to a wavelength, lumped elements can not be used easily, if at all. This accounts for the extensive use of distributed circuits at higher frequencies.
  • AN826 Crystal Oscillator Basics and Crystal Selection for Rfpic™ And

    AN826 Crystal Oscillator Basics and Crystal Selection for Rfpic™ And

    AN826 Crystal Oscillator Basics and Crystal Selection for rfPICTM and PICmicro® Devices • What temperature stability is needed? Author: Steven Bible Microchip Technology Inc. • What temperature range will be required? • Which enclosure (holder) do you desire? INTRODUCTION • What load capacitance (CL) do you require? • What shunt capacitance (C ) do you require? Oscillators are an important component of radio fre- 0 quency (RF) and digital devices. Today, product design • Is pullability required? engineers often do not find themselves designing oscil- • What motional capacitance (C1) do you require? lators because the oscillator circuitry is provided on the • What Equivalent Series Resistance (ESR) is device. However, the circuitry is not complete. Selec- required? tion of the crystal and external capacitors have been • What drive level is required? left to the product design engineer. If the incorrect crys- To the uninitiated, these are overwhelming questions. tal and external capacitors are selected, it can lead to a What effect do these specifications have on the opera- product that does not operate properly, fails prema- tion of the oscillator? What do they mean? It becomes turely, or will not operate over the intended temperature apparent to the product design engineer that the only range. For product success it is important that the way to answer these questions is to understand how an designer understand how an oscillator operates in oscillator works. order to select the correct crystal. This Application Note will not make you into an oscilla- Selection of a crystal appears deceivingly simple. Take tor designer. It will only explain the operation of an for example the case of a microcontroller.
  • AN-400 a Study of the Crystal Oscillator for CMOS-COPS

    AN-400 a Study of the Crystal Oscillator for CMOS-COPS

    AN-400 A Study Of The Crystal Oscillator For CMOS-COPS Literature Number: SNOA676 A Study of the Crystal Oscillator for CMOS-COPS AN-400 National Semiconductor A Study of the Crystal Application Note 400 Oscillator for Abdul Aleaf August 1986 CMOS-COPSTM INTRODUCTION TABLE I The most important characteristic of CMOS-COPS is its low A. Crystal oscillator vs. external squarewave COP410C power consumption. This low power feature does not exist change in current consumption as a function of frequen- in TTL and NMOS systems which require the selection of cy and voltage, chip held in reset, CKI is d4. low power IC's and external components to reduce power I e total power supply current drain (at VCC). consumption. Crystal The optimization of external components helps decrease the power consumption of CMOS-COPS based systems Inst. cyc. V f ImA even more. CC ckI time A major contributor to power consumption is the crystal os- 2.4V 32 kHz 125 ms 8.5 cillator circuitry. m Table I presents experimentally observed data which com- 5.0V 32 kHz 125 s83 pares the current drain of a crystal oscillator vs. an external 2.4V 1 MHz 4 ms 199 squarewave clock source. 5.0V 1 MHz 4 ms 360 The main purpose of this application note is to provide ex- perimentally observed phenomena and discuss the selec- External Squarewave tion of suitable oscillator circuits that cover the frequency Inst. cyc. range of the CMOS-COPS. V f I CC ckI time Table I clearly shows that an unoptimized crystal oscillator draws more current than an external squarewave clock.
  • Simple Blocking Oscillator Performance Analysis for Battery Voltage Enhancement

    Simple Blocking Oscillator Performance Analysis for Battery Voltage Enhancement

    Journal of Mobile Multimedia, Vol. 11, No.3&4 (2015) 321-329 © Rinton Press SIMPLE BLOCKING OSCILLATOR PERFORMANCE ANALYSIS FOR BATTERY VOLTAGE ENHANCEMENT DEWANTO HARJUNOWIBOWO ESMART, Physics Education Department, Sebelas Maret University, Indonesia [email protected] RESTU WIDHI HASTUTI Physics Education Department, Sebelas Maret University, Indonesia [email protected] KENNY ANINDIA RATOPO Physics Education Department, Sebelas Maret University, Indonesia [email protected] ANIF JAMALUDDIN ESMART, Physics Education Department, Sebelas Maret University, Indonesia [email protected] SYUBHAN ANNUR FKIP MIPA, Lambung Mangkurat University, Indonesia An application Blocking Oscillator (BO) on a battery to power a system LED lamp light detector has been built and compared with a standard system used phone cellular adapter as the power supply. The performance analysis was carried out to determine the efficiency of the blocking oscillator and its potency to be adopted in an electronic appliance using low voltage and current from a battery. Measurements were taken using an oscilloscope, a multimeter, and a light meter. The results show that the system generates electrical pulses of 1.5 to 7.6 VDC and powering the system normally. The system generates 3.167 mW powers to produce the intensity of 176 Lux. On the contrary, the standard system needs 1.8mW to produce 5 Lux. A LED usually takes at least 60mW to get 7150 Lux. Therefore, the system used a simple blocking oscillator seems potential to provide high voltage for powering electronic appliances with low current. Key words: blocking oscillator, characteristic, efficiency, LED, pulse 1 Introduction A design of circuit based on blocking oscillator for light up a LED using waste battery was carried out.
  • CLASS 331 OSCILLATORS January 2011

    CLASS 331 OSCILLATORS January 2011

    CLASS 331 OSCILLATORS 331 - 1 331 OSCILLATORS 94.1 MOLECULAR OR PARTICLE RESONANT 34 .Particular frequency control TYPE (E.G., MASER) means 1 R AUTOMATIC FREQUENCY STABILIZATION 35 ..Electromechanical (e.g., motor) USING A PHASE OR FREQUENCY 36 R ..Reactance device (e.g., SENSING MEANS variable capacitors, saturable 2 .Plural oscillators controlled inductors, reactance tubes, 3 .Molecular resonance etc.) stabilization 36 C ...Capacitor controlled AFC 4 .Search sweep of oscillator 36 L ...Inductor controlled AFC 5 .Magnetron oscillator 1 A .AFC with logic elements 6 .Klystron oscillator 37 BEAT FREQUENCY 7 ..Plural controls 38 .Plural beating 8 .Transistorized controls 39 ..Single channel 9 .Oscillator with distributed 40 .Frequency or amplitude parameter-type discriminator adjustment or control 10 .Plural A.F.S. for a single 41 .Frequency stabilization oscillator 42 .With particular signal combining 11 ..Plural comparators or means (e.g., cavity mixer) discriminators 43 ..With filter in mixer output 12 ...With phase-shifted inputs circuit 13 ..Motor control of oscillator 44 WITH FREQUENCY CALIBRATION OR 14 .With intermittent comparison TESTING controls 45 POLYPHASE OUTPUT 15 .Amplitude compensation 46 PLURAL OSCILLATORS 16 .Tuning compensation 47 .Oscillator used to vary 17 .Particular error voltage control amplitude or frequency of (e.g., intergrating network) another oscillator 18 .With reference oscillator or 48 .Adjustable frequency source 49 .Selectively connected to common 19 ..Spectrum reference source output or oscillator substitution
  • Sinusoidal and Non- Sinusoidal Oscillators

    Sinusoidal and Non- Sinusoidal Oscillators

    CHAPTER65 Learning Objectives ➣ What is an Oscillator? SINUSOIDAL ➣ Classification of Oscillators ➣ Damped and Undamped AND NON- Oscillations ➣ Oscillatory Circuit ➣ Essentials of a Feedback LC SINUSOIDAL Oscillator ➣ Tuned Base Oscillator ➣ Tuned Collector Oscillator OSCILLATORS ➣ Hartley Oscillator ➣ FET Hartley Oscillator ➣ Colpitts Oscillator ➣ Clapp Oscillator ➣ FET Colpitts Oscillator ➣ Crystal Controlled Oscillator ➣ Transistor Pierce Cystal Oscillator ➣ FET Pierce Oscillator ➣ Phase Shift Principle ➣ RC Phase Shift Oscillator ➣ Wien Bridge Oscillator ➣ Pulse Definitions ➣ Basic Requirements of a Sawtooth Generator ➣ UJT Sawtooth Generator ➣ Multivibrators (MV) ➣ Astable Multivibrator An oscillator is an electronic device used for ➣ Bistable Multivibrator (BMV) the purpose of generating a signal. Oscillators ➣ Schmitt Trigger are found in computers, wireless receivers ➣ Transistor Blocking Oscillator and transmitters, and audiofrequency equipment particularly music synthesizers 2408 Electrical Technology 65.1. What is an Oscillator ? An electronic oscillator may be defined in any one of the following four ways : 1. It is a circuit which converts dc energy into ac energy at a very high frequency; 2. It is an electronic source of alternating cur- rent or voltage having sine, square or sawtooth or pulse shapes; 3. It is a circuit which generates an ac output signal without requiring any externally ap- Oscillator plied input signal; 4. It is an unstable amplifier. These definitions exclude electromechanical alternators producing 50 Hz ac power or other devices which convert mechanical or heat energy into electric energy. 65.2. Comparison Between an Amplifier and an Oscillator As discussed in Chapter-10, an amplifier produces an output signal whose waveform is similar to the input signal but whose power level is generally high.
  • P020190719536109927550.Pdf

    P020190719536109927550.Pdf

    Integrated Circuits and Systems Series Editor Anantha Chandrakasan, Massachusetts Institute of Technology Cambridge, Massachusetts For other titles published in this series, go to www.springer.com/series/7236 Eric Vittoz Low-Power Crystal and MEMS Oscillators The Experience of Watch Developments Eric Vittoz Ecole Polytechnique Fédérale de Lausanne (EPFL) 1015 Lausanne Switzerland [email protected] ISSN 1558-9412 ISBN 978-90-481-9394-3 e-ISBN 978-90-481-9395-0 DOI 10.1007/978-90-481-9395-0 Springer Dordrecht Heidelberg London New York Library of Congress Control Number: 2010930852 © Springer Science+Business Media B.V. 2010 No part of this work may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, microfilming, recording or otherwise, without written permission from the Publisher, with the exception of any material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Cover design: Spi Publisher Services Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) To my wife Monique Contents Preface ...................................................... xi Symbols ..................................................... xiii 1 Introduction ............................................. 1 1.1 Applications of Quartz Crystal Oscillators. ................ 1 1.2 HistoricalNotes ...................................... 2 1.3 TheBookStructure...................................
  • Simple Blocking Oscillator for Waste Battery's Voltage Enhancement

    Simple Blocking Oscillator for Waste Battery's Voltage Enhancement

    International Journal of Information and Electronics Engineering, Vol. 6, No. 2, March 2016 Simple Blocking Oscillator for Waste Battery’s Voltage Enhancement Dewanto Harjunowibowo, Wiwit Widiawati, Anif Jamaluddin, and Furqon Idris zero. Since VBB<<VCC and does not affect the operation of Abstract—A system based on Blocking Oscillator (BO) has circuit therefore it can be neglected. been built and potentially produces high gain pulses voltage. This paper aims to discuss characteristic, work principle, and its potency of simple blocking oscillator to optimize batteries usage. The measurement of its peak to peak voltage (Vpp) and root means square voltage (Vrms) were conducted using digital oscilloscope and digital voltmeter. The experiment proves that the system produces high gain pulse electricity and driven LED without broke it out. The system could power a white LED 3.0-4.0 V using an input voltage of 0.98 VDC from waste battery. Using blocking oscillator, a battery may be used longer and more efficient until the battery energy almost ramps out to 0.5V. Index Terms—Blocking oscillator, characteristic, gain, led. Fig. 1. A triggered transistor blocking oscillator with base timing. Suppose a triggering signal is momentarily applied to the I. INTRODUCTION collector to lower its voltage. By transformer action, the base In order to increase battery life, some experiments has been will rise in potential. After VBE exceeds the cut in voltage, done, such as to design circuit building blocks with lower the transistor saturates and starts to draw current. The increase supply voltage and consuming sub-microwatt power. in collector current lowers the collector voltage, which in turn Reference [1] has built a circuit design which generates a DC raises the base voltage.
  • Oscilators Simplified

    Oscilators Simplified

    SIMPLIFIED WITH 61 PROJECTS DELTON T. HORN SIMPLIFIED WITH 61 PROJECTS DELTON T. HORN TAB BOOKS Inc. Blue Ridge Summit. PA 172 14 FIRST EDITION FIRST PRINTING Copyright O 1987 by TAB BOOKS Inc. Printed in the United States of America Reproduction or publication of the content in any manner, without express permission of the publisher, is prohibited. No liability is assumed with respect to the use of the information herein. Library of Cangress Cataloging in Publication Data Horn, Delton T. Oscillators simplified, wtth 61 projects. Includes index. 1. Oscillators, Electric. 2, Electronic circuits. I. Title. TK7872.07H67 1987 621.381 5'33 87-13882 ISBN 0-8306-03751 ISBN 0-830628754 (pbk.) Questions regarding the content of this book should be addressed to: Reader Inquiry Branch Editorial Department TAB BOOKS Inc. P.O. Box 40 Blue Ridge Summit, PA 17214 Contents Introduction vii List of Projects viii 1 Oscillators and Signal Generators 1 What Is an Oscillator? - Waveforms - Signal Generators - Relaxatton Oscillators-Feedback Oscillators-Resonance- Applications--Test Equipment 2 Sine Wave Oscillators 32 LC Parallel Resonant Tanks-The Hartfey Oscillator-The Coipltts Oscillator-The Armstrong Oscillator-The TITO Oscillator-The Crystal Oscillator 3 Other Transistor-Based Signal Generators 62 Triangle Wave Generators-Rectangle Wave Generators- Sawtooth Wave Generators-Unusual Waveform Generators 4 UJTS 81 How a UJT Works-The Basic UJT Relaxation Oscillator-Typical Design Exampl&wtooth Wave Generators-Unusual Wave- form Generator 5 Op Amp Circuits
  • Single Transistor Crystal Oscillator Circuits

    Single Transistor Crystal Oscillator Circuits

    Copyright © 2009 Rakon Limited SINGLE TRANSISTOR CRYSTAL OSCILLATOR CIRCUITS The majority of modern crystal oscillator circuits fall into one of two design categories, the Colpitts / Clapp oscillator and the Pierce oscillator. There are other types of single transistor oscillators ( Hartley and Butler for example ), but their usefulness and application is beyond the scope of this discussion. For an electronic circuit to oscillate there are two criteria which must be satisfied. It must contain an amplifier with sufficient gain to overcome the losses of the feedback network (quartz crystal in this case) and the phase shift around the whole circuit is 0 o or some integer multiple of 360 o. To design a crystal oscillator the above has to be true but there are a myriad of other considerations including crystal power dissipation, unwanted mode suppression, crystal loading (the actual impedance the crystal sees once oscillation has started) and the introduction of a non-linearity in the gain to limit the oscillation build-up. Consider the apparently simple circuit of the Colpitts / Clapp oscillator in Fig. 1. Without the correct simulation tools it is not immediately obvious this circuit has Negative Resistance at the frequency of oscillation (necessary to over come the crystals Equivalent Series Resistance), an initial gain in excess of one (to allow oscillator start- up) which drops to unity once the oscillation starts, and is then subsequently stabilised by either the voltage limiting on the transistor’s base emitter junction, or transistor collector current starvation. For AT cut crystals this circuit, with careful choice of the component values, can be made to oscillate from about 1MHz to above 200MHz with complete control over the crystal drive level and crystal loading impedance.
  • Generation of Broad-Band Chaos Using Blocking Oscillator Nikolai F

    Generation of Broad-Band Chaos Using Blocking Oscillator Nikolai F

    IEEE TRANSACTIONS ON CIRCUITS AND SYSTEMS—I: FUNDAMENTAL THEORY APPLICATIONS, VOL. 48, NO. 6, JUNE 2001 673 Generation of Broad-Band Chaos Using Blocking Oscillator Nikolai F. Rulkov and Alexander R. Volkovskii Abstract—In this paper, we discuss fundamentals for the design of a source of chaotic signals based on a blocking oscillator circuit. We study a modification of a well-known circuit of blocking os- cillator which leads to the onset of chaotic oscillations. The output signal of such chaotic oscillator is a series of short term pulses char- acterized by chaotic fluctuations of time intervals between pulses. Such chaotic pulse signals posses a broad-band continuous power spectrum and short correlation length. We discuss the results of theoretical and experimental studies of nonlinear dynamics of the chaotic blocking oscillator. Index Terms—Bifurcations, chaos, nonlinear circuits. I. INTRODUCTION NTENSIVE studies of possible applications of chaotic sig- I nals are supported in part by the abilities of simple inex- pensive electrical circuits to generate complex chaotic signals. Quite a few simple autonomous nonlinear circuits that posses chaotic dynamics have been proposed and studied, see for ex- Fig. 1. Chaotic blocking oscillator circuit. ample [1]–[6]. Most of these nonlinear circuits produce chaotic signals in form of quasiharmonic oscillations. Chaos in such cir- stead of quasiharmonic chaotic signals are discussed in details cuits occurs through bifurcations from a regime of harmonic os- in [10], [12], [13]. cillation. The shape of the power spectrum of such chaotic sig- The core of the chaotic pulse oscillators is a circuit that gener- nals depends upon the amplitudes of higher harmonics which ates time intervals in accordance with the iterations of a chaotic occur due to nonlinear distortions of the original harmonic os- map.
  • W9HE Amplifiers

    W9HE Amplifiers

    Introduction Rather than try to give you the material so that you can answer the questions from “first principles," I will provide enough information that you can recognize the correct answer to each question. Chapter 6 Notes In no particular order, the necessary “nuggets:” 1. Junction transistors are current controlled and therefore have relatively low input impedance. Field effect devices, including vacuum tubes, are voltage controlled and therefore have relatively high input impedance. Vacuum tubes are implicitly diodes as well. Transistor input and output elements can be reversed and the device would operate somewhat. 2. See attached amplifier circuits sheet. Another phrase for “common word" amplifer is “grounded word" amplifer. The key is determining which lead is at signal ground level. The lead may not be at DC ground for bias reasons. If a lead is connected to the power supply via a capacitor in parallel with a resistor then that lead is at signal ground. 3. See attached oscillators circuits sheet. Oscillators can be built using any type of amplifier. All that is required is a gain greater than 1 with positive feed back. The major classes of oscillators are named according to the method of providing that feedback. If the feedback circuit is a divided capacitor, then the oscillator is a Colpitts oscillator. The memory key is C for capacitance. If the feedback circuit is a divided inductor, then the oscillator is a Hartley oscillator. The memory key is H for Henries of inductance. If the feedback circuit is a crystal, then the oscillator os a Pierce oscillator.