Oscilators Simplified
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Chapter 3: Data Transmission Terminology
Chapter 3: Data Transmission CS420/520 Axel Krings Page 1 Sequence 3 Terminology (1) • Transmitter • Receiver • Medium —Guided medium • e.g. twisted pair, coaxial cable, optical fiber —Unguided medium • e.g. air, seawater, vacuum CS420/520 Axel Krings Page 2 Sequence 3 1 Terminology (2) • Direct link —No intermediate devices • Point-to-point —Direct link —Only 2 devices share link • Multi-point —More than two devices share the link CS420/520 Axel Krings Page 3 Sequence 3 Terminology (3) • Simplex —One direction —One side transmits, the other receives • e.g. Television • Half duplex —Either direction, but only one way at a time • e.g. police radio • Full duplex —Both stations may transmit simultaneously —Medium carries signals in both direction at same time • e.g. telephone CS420/520 Axel Krings Page 4 Sequence 3 2 Frequency, Spectrum and Bandwidth • Time domain concepts —Analog signal • Varies in a smooth way over time —Digital signal • Maintains a constant level then changes to another constant level —Periodic signal • Pattern repeated over time —Aperiodic signal • Pattern not repeated over time CS420/520 Axel Krings Page 5 Sequence 3 Analogue & Digital Signals Amplitude (volts) Time (a) Analog Amplitude (volts) Time (b) Digital CS420/520 Axel Krings Page 6 Sequence 3 Figure 3.1 Analog and Digital Waveforms 3 Periodic A ) s t l o v ( Signals e d u t 0 i l p Time m A –A period = T = 1/f (a) Sine wave A ) s t l o v ( e d u 0 t i l Time p m A –A period = T = 1/f CS420/520 Axel Krings Page 7 (b) Square wave Sequence 3 Figure 3.2 Examples of Periodic Signals Sine Wave • Peak Amplitude (A) —maximum strength of signal, in volts • FreQuency (f) —Rate of change of signal, in Hertz (Hz) or cycles per second —Period (T): time for one repetition, T = 1/f • Phase (f) —Relative position in time • Periodic signal s(t +T) = s(t) • General wave s(t) = Asin(2πft + Φ) CS420/520 Axel Krings Page 8 Sequence 3 4 Periodic Signal: e.g. -
Unit-1 Mphycc-7 Ujt
UNIT-1 MPHYCC-7 UJT The Unijunction Transistor or UJT for short, is another solid state three terminal device that can be used in gate pulse, timing circuits and trigger generator applications to switch and control either thyristors and triac’s for AC power control type applications. Like diodes, unijunction transistors are constructed from separate P-type and N-type semiconductor materials forming a single (hence its name Uni-Junction) PN-junction within the main conducting N-type channel of the device. Although the Unijunction Transistor has the name of a transistor, its switching characteristics are very different from those of a conventional bipolar or field effect transistor as it can not be used to amplify a signal but instead is used as a ON-OFF switching transistor. UJT’s have unidirectional conductivity and negative impedance characteristics acting more like a variable voltage divider during breakdown. Like N-channel FET’s, the UJT consists of a single solid piece of N-type semiconductor material forming the main current carrying channel with its two outer connections marked as Base 2 ( B2 ) and Base 1 ( B1 ). The third connection, confusingly marked as the Emitter ( E ) is located along the channel. The emitter terminal is represented by an arrow pointing from the P-type emitter to the N-type base. The Emitter rectifying p-n junction of the unijunction transistor is formed by fusing the P-type material into the N-type silicon channel. However, P-channel UJT’s with an N- type Emitter terminal are also available but these are little used. -
Optoelectronic Oscillators: Recent and Emerging Trends Optoelectronic Oscillators: Recent and Emerging Trends
Optoelectronic Oscillators: Recent and Emerging Trends Optoelectronic Oscillators: Recent and Emerging Trends October 11, 2018 Afshin S. Daryoush(1), Ajay Poddar(2), Tianchi Sun(1), and Ulrich L. Rohde(2), Drexel University(1); Synergy Microwave(2) Highly stable oscillators are key components in many important applications where coherent processing is performed for improved detection. The optoelectronic oscillator (OEO) exhibits low phase noise at microwave and mmWave frequencies, which is attractive for applications such as synthetic aperture radar, space communications, navigation and meteorology, as well as for communications carriers operating at frequencies above 10 GHz, with the advent of high data rate wireless for high speed data transmission. The conventional OEO suffers from a large number of unwanted, closely-spaced oscillation modes, large size and thermal drift. State-of-the- art performance is reported for X- and K-Band OEO synthesizers incorporating a novel forced technique of self-injection locking, double self phase-locking. This technique reduces phase noise both close-in and far-away from the carrier, while suppressing side modes observed in standard OEOs. As an example, frequency synthesizers at X-Band (8 to 12 GHz) and K-Band (16 to 24 GHz) are demonstrated, typically exhibiting phase noise at 10 kHz offset from the carrier better than −138 and −128 dBc/Hz, respectively. A fully integrated version of a forced tunable low phase noise OEO is also being developed for 5G applications, featuring reduced size and power consumption, less sensitivity to environmental effects and low cost. Electronic oscillators generate low phase noise signals up to a few GHz but suffer phase noise degradation at higher frequencies, principally due to low Q-factor resonators. -
JRE SCHOOL of Engineering
JRE SCHOOL OF Engineering PUT EXAMINATION SET-A MAY 2015 Subject Name Microwave Engineering Subject Code EEC 603 Roll No. of Student Max Marks 100 Max Duration 3 hrs Date 02/05/2015 Time 10:00 a.m. to 1:00 p.m. For Branches: EC Branch only (6th sem) Q. 1 Attempt any FOUR from the following. All question carry equal marks. (5 X 4 = 20) a) A TE11 wave is propagating in a air-filled circular waveguide of diameter 12cm at 2.5GHz, find the cutoff frequency, guide wavelength, wave impedance in the guide. b) Show that TM01 and TM10 modes do not exist in a rectangular waveguide. c) What is a microstrip line? Compare microstrip lines with striplines. Write advantages and disadvantages of both. Microstrip Transmission Line: It is also called open strip line because of the openness of its structure. It has very simple geometry. It is an unsymmetrical strip line that is nothing but a parallel plate transmission line having dielectric substrate, the on face of which is metallised ground and the other (top) face, has thin conducting strip of certain width ‘w’ and thickness ‘t’. The top ground plate is not present and so cover plate is used for shielding purpose. Modes are only quasi TEM, thus the theory of TEM coupled lines applies only. Losses: (i) Dielectric loss in substrate (ii) ohmic skin losses in conductor strip and ground plane. Advantages: (i) Simple construction (ii) easier integration with semiconductor device (iii) fabrication cosh is lower (iv) package and unpacked semiconductor chips can be attached to these lines. -
Ariel Moss EE 254 Project 6 12/6/13 Project 6: Oscillator Circuits The
Ariel Moss EE 254 Project 6 12/6/13 Project 6: Oscillator Circuits The purpose of this experiment was to design two oscillator circuits: a Wien-Bridge oscillator at 3 kHz oscillation and a Hartley Oscillator using a BJT at 5 kHz oscillation. The first oscillator designed was a Wien-Bridge oscillator (Figure 1). Before designing the circuit, some background information was collected. An input signal sent to the non-inverting terminal with a parallel and series RC configuration as well as two resistors connected in inverting circuit types to achieve gain. The circuit works because the RC network is connected to the positive feedback part of the amplifier, and has a zero phase shift at a frequency. At the oscillation frequency, the voltages applied to both the inputs will be in phase, which causes the positive and negative feedback to cancel out. This causes the signal to oscillate. To calculate the time constant given the cutoff frequency, Calculation 1 was used. The capacitor was chosen to be 0.1µF, which left the input, series, and parallel resistors to be 530Ω and the output resistor to be 1.06 kHz. The signal was then simulated in PSPICE, and after adjusting the output resistor to 1.07Ω, the circuit produced a desired simulation with time spacing of .000335 seconds, which was very close to the calculated time spacing. (Figures 2-3 and Calculations 2-3). R2 1.07k 10Vdc V1 R1 LM741 4 2 V- 1 - OS1 530 6 OUT 0 3 5 + 7 OS2 U1 V+ V2 10Vdc Cs Rs 0.1u 530 Cp Rp 0.1u 530 0 Figure 2: Wien-Bridge Oscillator built in PSPICE Ariel Moss EE 254 Project 6 12/6/13 Figure 3: Simulation of circuit Next the circuit was built and tested. -
Chapter 19 - the Oscillator
Chapter 19 - The Oscillator The Electronics Curse “Your amplifiers will oscillate, your oscillators won't!” Question, What is an Oscillator? A Pendulum is an Oscillator... “Oscillators are circuits that are used to generate A.C. signals. Although mechanical methods, like alternators, can be used to generate low frequency A.C. signals, such as the 50 Hz mains, electronic circuits are the most practical way of generating signals at radio frequencies.” Comment: Hmm, wasn't always. In the time of Marconi, generators were used to generate a frequency to transmit. We are talking about kiloWatts of power! e.g. Grimeton L.F. Transmitter. Oscillators are widely used in both transmitters and receivers. In transmitters they are used to generate the radio frequency signal that will ultimately be applied to the antenna, causing it to transmit. In receivers, oscillators are widely used in conjunction with mixers (a circuit that will be covered in a later module) to change the frequency of the received radio signal. Principal of Operation The diagram below is a ‘block diagram’ showing a typical oscillator. Block diagrams differ from the circuit diagrams that we have used so far in that they do not show every component in the circuit individually. Instead they show complete functional blocks – for example, amplifiers and filters – as just one symbol in the diagram. They are useful because they allow us to get a high level overview of how a circuit or system functions without having to show every individual component. The Barkhausen Criterion [That's NOT ‘dog box’ in German!] Comment: In electronics, the Barkhausen stability criterion is a mathematical condition to determine when a linear electronic circuit will oscillate. -
Analysis of BJT Colpitts Oscillators - Empirical and Mathematical Methods for Predicting Behavior Nicholas Jon Stave Marquette University
Marquette University e-Publications@Marquette Master's Theses (2009 -) Dissertations, Theses, and Professional Projects Analysis of BJT Colpitts Oscillators - Empirical and Mathematical Methods for Predicting Behavior Nicholas Jon Stave Marquette University Recommended Citation Stave, Nicholas Jon, "Analysis of BJT Colpitts sO cillators - Empirical and Mathematical Methods for Predicting Behavior" (2019). Master's Theses (2009 -). 554. https://epublications.marquette.edu/theses_open/554 ANALYSIS OF BJT COLPITTS OSCILLATORS – EMPIRICAL AND MATHEMATICAL METHODS FOR PREDICTING BEHAVIOR by Nicholas J. Stave, B.Sc. A Thesis submitted to the Faculty of the Graduate School, Marquette University, in Partial Fulfillment of the Requirements for the Degree of Master of Science Milwaukee, Wisconsin August 2019 ABSTRACT ANALYSIS OF BJT COLPITTS OSCILLATORS – EMPIRICAL AND MATHEMATICAL METHODS FOR PREDICTING BEHAVIOR Nicholas J. Stave, B.Sc. Marquette University, 2019 Oscillator circuits perform two fundamental roles in wireless communication – the local oscillator for frequency shifting and the voltage-controlled oscillator for modulation and detection. The Colpitts oscillator is a common topology used for these applications. Because the oscillator must function as a component of a larger system, the ability to predict and control its output characteristics is necessary. Textbooks treating the circuit often omit analysis of output voltage amplitude and output resistance and the literature on the topic often focuses on gigahertz-frequency chip-based applications. Without extensive component and parasitics information, it is often difficult to make simulation software predictions agree with experimental oscillator results. The oscillator studied in this thesis is the bipolar junction Colpitts oscillator in the common-base configuration and the analysis is primarily experimental. The characteristics considered are output voltage amplitude, output resistance, and sinusoidal purity of the waveform. -
AM Transmitters
Chapter 4: AM Transmitters Chapter 4 Objectives At the conclusion of this chapter, the reader will be able to: • Draw a block diagram of a high or low-level AM transmitter, giving typical signals at each point in the circuit. • Discuss the relative advantages and disadvantages of high and low-level AM transmitters. • Identify an RF oscillator configuration, pointing out the components that control its frequency. • Describe the physical construction of a quartz crystal. • Calculate the series and parallel resonant frequencies of a quartz crystal, given manufacturer's data. • Identify the resonance modes of a quartz crystal in typical RF oscillator circuits. • Describe the operating characteristics of an RF amplifier circuit, given its schematic diagram. • Explain the operation of modulator circuits. • Identify the functional blocks (amplifiers, oscillators, etc) in a schematic diagram. • List measurement procedures used with AM transmitters. • Develop a plan for troubleshooting a transmitter. In Chapter 3 we studied the theory of amplitude modulation, but we never actually built an AM transmitter. To construct a working transmitter (or receiver), a knowledge of RF circuit principles is necessary. A complete transmitter consists of many different stages and hundreds of electronic components. When beginning technicians see the schematic diagram of a "real" electronic system for the first time, they're overwhelmed. A schematic contains much valuable information. But to the novice, it's a swirling mass of resistors, capacitors, coils, transistors, and IC chips, all connected in a massive web of wires! How can anyone understand this? All electronic systems, no matter how complex, are built from functional blocks or stages. -
(12) United States Patent (10) Patent No.: US 7,994,744 B2 Chen (45) Date of Patent: Aug
US007994744B2 (12) United States Patent (10) Patent No.: US 7,994,744 B2 Chen (45) Date of Patent: Aug. 9, 2011 (54) METHOD OF CONTROLLING SPEED OF (56) References Cited BRUSHLESS MOTOR OF CELING FAN AND THE CIRCUIT THEREOF U.S. PATENT DOCUMENTS 4,546,293 A * 10/1985 Peterson et al. ......... 3.18/400.14 5,309,077 A * 5/1994 Choi ............................. 318,799 (75) Inventor: Chien-Hsun Chen, Taichung (TW) 5,748,206 A * 5/1998 Yamane .......................... 34.737 2007/0182350 A1* 8, 2007 Patterson et al. ............. 318,432 (73) Assignee: Rhine Electronic Co., Ltd., Taichung County (TW) * cited by examiner Primary Examiner — Bentsu Ro (*) Notice: Subject to any disclaimer, the term of this (74) Attorney, Agent, or Firm — Browdy and Neimark, patent is extended or adjusted under 35 PLLC U.S.C. 154(b) by 539 days. (57) ABSTRACT The present invention relates to a method and a circuit of (21) Appl. No.: 12/209,037 controlling a speed of a brushless motor of a ceiling fan. The circuit includes a motor PWM duty consumption sampling (22) Filed: Sep. 11, 2008 unit and a motor speed sampling to sense a PWM duty and a speed of the brushless motor. A central processing unit is (65) Prior Publication Data provided to compare the PWM duty and the speed of the brushless motor to a preset maximum PWM duty and a preset US 201O/OO6O224A1 Mar. 11, 2010 maximum speed. When the PWM duty reaches to the preset maximum PWM duty first, the central processing unit sets the (51) Int. -
Oscillator Design
Oscillator Design •Introduction –What makes an oscillator? •Types of oscillators –Fixed frequency or voltage controlled oscillator –LC resonator –Ring Oscillator –Crystal resonator •Design of oscillators –Frequency control, stability –Amplitude limits –Buffered output –isolation –Bias circuits –Voltage control –Phase noise 1 Oscillator Requirements •Power source •Frequency-determining components •Active device to provide gain •Positive feedback LC Oscillator fr = 1/ 2p LC Hartley Crystal Colpitts Clapp RC Wien-Bridge Ring 2 Feedback Model for oscillators x A(jw) i xo A (jw) = A f 1 - A(jω)×b(jω) x = x + x d i f Barkhausen criteria x f A( jw)× b ( jω) =1 β Barkhausen’scriteria is necessary but not sufficient. If the phase shift around the loop is equal to 360o at zero frequency and the loop gain is sufficient, the circuit latches up rather than oscillate. To stabilize the frequency, a frequency-selective network is added and is named as resonator. Automatic level control needed to stabilize magnitude 3 General amplitude control •One thought is to detect oscillator amplitude, and then adjust Gm so that it equals a desired value •By using feedback, we can precisely achieve GmRp= 1 •Issues •Complex, requires power, and adds noise 4 Leveraging Amplifier Nonlinearity as Feedback •Practical trans-conductance amplifiers have saturating characteristics –Harmonics created, but filtered out by resonator –Our interest is in the relationship between the input and the fundamental of the output •As input amplitude is increased –Effective gain from input -
Thyristors.Pdf
THYRISTORS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. Thyristors Thyristors are a class of semiconductor devices characterized by 4-layers of alternating p and n material. Four-layer devices act as either open or closed switches; for this reason, they are most frequently used in control applications. Some thyristors and their symbols are (a) 4-layer diode (b) SCR (c) Diac (d) Triac (e) SCS Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The 4-layer diode (or Shockley diode) is a type of thyristor that acts something like an ordinary diode but conducts in the forward direction only after a certain anode to cathode voltage called the forward-breakover voltage is reached. The basic construction of a 4-layer diode and its schematic symbol are shown The 4-layer diode has two leads, labeled the anode (A) and the Anode (A) A cathode (K). p 1 n The symbol reminds you that it acts 2 p like a diode. It does not conduct 3 when it is reverse-biased. n Cathode (K) K Electronic Devices, 9th edition © 2012 Pearson Education. Upper Saddle River, NJ, 07458. Thomas L. Floyd All rights reserved. The Four-Layer Diode The concept of 4-layer devices is usually shown as an equivalent circuit of a pnp and an npn transistor. Ideally, these devices would not conduct, but when forward biased, if there is sufficient leakage current in the upper pnp device, it can act as base current to the lower npn device causing it to conduct and bringing both transistors into saturation. -
Silicon Bipolar Distributed Oscillator Design and Analysis
Science World Journal Vol 9 (No 4) 2014 www.scienceworldjournal.org ISSN 1597-6343 SILICON BIPOLAR DISTRIBUTED OSCILLATOR DESIGN AND ANALYSIS Article Research Full Length Aku, M. O. and *Imam, R. S. Department of Physics, Bayero University, Kano-Nigeria * Department of Physics, Kano University of Science and Technology, Wudil-Nigeria ABSTRACT between its input and output. It can be shown that there is a The design of high frequency silicon bipolar oscillator using trade-off between the bandwidth and delay in an amplifier common emitter (CE) with distributed output and analysis is (Lee, 1998). Distributed amplification provides a means to carried out. The general condition for oscillation and the take advantage of this trade-off in applications where the resulting analytical expressions for the frequency of delay is not a critical specification of the system and can be oscillators were reviewed. Transmission line design was compromised in favour of the bandwidth (distributed carried out using Butterworth LC filters in which the oscillator). It is noteworthy that the physical size of a normalised values and where used to obtain the distributed amplifier does not have to be comparable to the actual values of the inductors and capacitors used; this wavelength for it to enhance the bandwidth. Dividing the gain largely determines the performance of distributed oscillators. between multiple active devices avoids the concentration of The values of inductor and capacitors in the phase shift the parasitic at one place and hence eliminates a dominant network are used in tuning the oscillator. The simulated pole scenario in the frequency domain transfer function.