DOCSLIB.ORG

Biasing Techniques for Linear Power Amplifiers Anh Pham

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Biasing Techniques for Linear Power Amplifiers Anh Pham Biasing Techniques for Linear Power Amplifiers by Anh Pham Bachelor of Science in Electrical Engineering and Economics California Institute of Technology, June 2000 Submitted to the Department of Electrical Engineering and Computer Science in partial fulfillment of the requirements for the degree of Engineering and Computer Science Master of Engineering in Electrical 8ARKER at the &UASCHUSMrSWi#DTE OF TECHNOLOGY MASSACHUSETTS INSTITUTE OF TECHNOLOGY JUL 3 12002 May 2002 LIBRARIES @ Massachusetts Institute of Technology 2002. All right reserved. Author Department of Electrical Engineering and Computer Science May 2002 Certified by _ Charles G. Sodini Professor of Electrical Engineering and Computer Science Thesis Supervisor Accepted by Arthuf-rESmith, Ph.D. Chairman, Committee on Graduate Students Department of Electrical Engineering and Computer Science 2 Biasing Techniques for Linear Power Amplifiers by Anh Pham Submitted to the Department of electrical Engineering and Computer Science on May 10, 2002 in partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering and Computer Science Abstract Power amplifiers with conventional fixed biasing attain their best efficiency when operate at the maximum output power. For lower output level, these amplifiers are very inefficient. This is the major shortcoming in recent wireless applications with an adaptive power design; where the desired output power is a function of the bit-error rate, channel characteristics, modulation schemes, etc. Such applications require the power amplifier to have an optimum performance not only at the peak output level, but also across the adaptive power range. An adaptive biasing topology is proposed and implemented in the design of a power amplifier intended for use in the WiGLAN (Wireless Gigabits per second Local Area Network) project. Conceptually, the adaptive biasing circuitry senses the input signal, scales appropriately, then takes the average. The result dc signal is used to moderate the biasing current for the power transistors. The bias level is; therefore, a function of the input signal. By selecting the appropriate scaling factor, the biasing current can be adjusted to improve the efficiency across a wide range of operating power levels. The power amplifier that was designed, has two stages with a nominal gain of 17.3dB. The output at 1 -dB compression point is 20dBm. Both stages employ the adaptive biasing technique. The peak efficiency is 35% at l9dBm output power while the mid-range operation efficiency shows a significant improvement from conventional fixed biasing. Operating at 5.8GHz center frequency, the amplifier also exhibits good linearity with -56.66dBc and -58.1 ldBc, 2n and 3rd harmonics, respectively, at maximum output power. 3 4 Acknowledgements The work presented in this thesis could not have happened without the help and support of many people. First, I would like to thank Professor Charles Sodini for providing me with this research opportunity. His guidance is instrumental and his intuition approach to technical problems is intriguing. I am also greatly indebted to all of my colleagues in the H. S. Lee and C. G. Sodini research groups. Don Hitko vast knowledge and experience in circuit design are essential to the completion of this thesis work. Todd Sepke is always patient and helpful with design tools and other computing issues. I found solutions for a lot of the problems during our countless coffee break discussions. I would like to thank Andy Wang for his help on system issues that I often ran into during the course of this thesis. Andrew Chen and Mark Peng seem to know all the tricks to get things done around MIT, and are willing to offer their assistance. Andrew is the photographer for all the photos presented in this thesis. I greatly appreciate all the groups' members for making our office a friendly and supportive research environment. I would like to express my gratitude to Jeff Gross, and Eric Johnson at IBM for their support on the SiGe process. Aiman Shabra, a former colleague, and Bob Broughton at ADI offered tremendous help with packaging. I am grateful for their kind support. Vickram Vathulya at Philips Research USA introduced me to integrated power amplifier design and shared his industry "how-to" experience many times thereafter. I would like to thank Philips Research USA, especially Satyen Mukherjee and Tirdad Sowlati, for giving me the opportunity to design power amplifiers for GSM and CDMA cellular phones. Marilyn Pierce helps me greatly with all the deadlines and administrative requirements that I often overlook. I greatly appreciate her dedication. I would like to thank Pat Varley, and her successor Kathy Patenaud, for their help with all the purchasing and paperwork. I would like to thank my parents for their support and encouragement. Their love for me is simply boundless. And there is Ha, who is always there for me. 5 6 Contents I Introduction ....................................................................................................................... 13 1.1 Pow er Am plifier Biasing .......................................................................................... 14 1.2 Efficiency...................................................................................................................... 14 1.3 Fully Integrated Pow er Am plifier Issues .................................................................... 16 1.4 The W iG LAN Project ................................................................................................... 16 1.5 Thesis Overview ........................................................................................................ 16 2 N onlinearities and Pow er Link B udget .................................................................. 19 2.1 D istortion ...................................................................................................................... 19 2.1.1 H arm onics ........................................................................................................ 20 2.1.2 1-dB Compression ............................................................................................. 21 2.1.3 IIP 3 and Interm odulation Products .................................................................... 21 2.2 Receiver Sensitivity and Bit-Error-Rate (BER)......................................................... 23 2.3 Path Loss....................................................................................................................... 25 2.4 Pow er Link Budget .................................................................................................... 26 3 C onducting Pow er A mplifiers .................................................................................. 29 3.1 Class-A .......................................................................................................................... 30 3.2 Reduced Conduction Angle Mode, Class-AB, B and C ........................................... 32 4 B iasing T echniques...................................................................................................... 39 4.1 Current M irror N etw ork............................................................................................. 39 4.1.1 H ow does it w ork? .................................................. ......................................... 40 4.1.2 Effects on gain, linearity, and efficiency ........................................................... 41 4.2 D iode-Connect .............................................................................................................. 43 4.2.1 H ow does it w ork? ..................................................... ........................................... 43 4.2.2 Effects on gain, linearity, and efficiency ........................................................... 43 4.3 Cascode Current M irror ............................................................................................. 45 4.3.1 H ow does it w ork? .................................................. ......................................... 45 4.3.2 Effects on gain, linearity, and efficiency ........................................................... 46 4.4 A daptive Biasing....................................................................................................... 47 4.4.1 The Concept ...................................................................................................... 47 4.4.2 H ow does it w ork? ..................................................... ........................................... 48 4.4.3 Effects on gain, linearity, and efficiency ........................................................... 50 4.4.4 The A veraging Circuit ...................................................................................... 51 7 5 D esigning a C lass-A Pow er A m plifier ....................................................................... 55 5.1 Optim al Load and Output M atching N etw ork ........................................................... 55 5.1.1 Conjugate M atch vs. Pow er M atch.................................................................... 55 5.1.2 Optim al Load ...................................................................................................... 56 5.1.3 M atching N etw orks........................................................................................... 58 5.2 Transistor Size and Biasing Point............................................................................
Load more

Recommended publications
  • Spectrum Management Technical Handbook
    NTIA TN 89-2 SPECTRUM MANAGEMENT TECHNICAL HANDBOOK TECHNICAL NOTE SERIES NTIA TECHNICAL NOTE 89-2 SPECTRUM MANAGEMENT TECHNICAL HANDBOOK l U.S. DEPARTMENT OF COMMERCE Robert A. Mosbacher, Secretary Alfred C. Sikes, Assistant Secretary for Communications and Information JULY 1989 ACKNOWLEDGEMENT NT IA acknowledges the efforts of Mark Schellhammer in the completion of Phase I of this handbook (Sections 1-3). Other portions will be added as resources are available. ABSTRACT This handbook is a compilation of the procedures, definitions, relationships and conversions essential to electromagnetic compatibility analysis. It is intended as a reference for NTIA engineers. KEY WORDS CONVERSION FACTORS COUPLING EQUATIONS DEFINITIONS ·TECHNICAL RELATIONSHIPS iii TABLE OF CONTENTS Subsection Page SECTION 1 TECHNICAL TERMS:DEFINITIONS AND NOTATION TERMS AND DEFINITIONS . .. .. 1-1 GLOSSARY OF STANDARD NOTATION . .. 1-13 SECTION 2 TECHNICAL RELATIONSHIPS AND CONVERSION FACTORS INTRODUCTION . .. .. .. 2-1 TRANSMISSION LOSS FOR RADIO LINKS . �. .. .. 2-1 Propagation Loss . .. .. .. 2-1 Transmission Loss ........................................ 2-2 Free-Space Basic Transmission Loss .......................... 2-2 Basic Transmission Loss .................................... 2-2 Loss Relative to Free-Space .................................. 2-2 System Loss . .. 2-3 ; Total Loss . .. .. 2-3 ANTENNA CHARACTERISTICS . .. 2-3 Antenna Directivity ........................................ 2-3 Antenna Gain and Efficiency .................................. 2-3 I
    [Show full text]
  • Valve Biasing
    VALVE AMP BIASING Biased information How have valve amps survived over 30 years of change? Derek Rocco explains why they are still a vital ingredient in music making, and talks you through the mysteries of biasing N THE LAST DECADE WE HAVE a signal to the grid it causes a water as an electrical current, you alter the negative grid voltage by seen huge advances in current to flow from the cathode to will never be confused again. When replacing the resistor I technology which have the plate. The grid is also known as your tap is turned off you get no to gain the current draw required. profoundly changed the way we the control grid, as by varying the water flowing through. With your Cathode bias amplifiers have work. Despite the rise in voltage on the grid you can control amp if you have too much negative become very sought after. They solid-state and digital modelling how much current is passed from voltage on the grid you will stop have a sweet organic sound that technology, virtually every high- the cathode to the plate. This is the electrical current from flowing. has a rich harmonic sustain and profile guitarist and even recording known as the grid bias of your amp This is known as they produce a powerful studios still rely on good ol’ – the correct bias level is vital to the ’over-biased’ soundstage. Examples of these fashioned valves. operation and tone of the amplifier. and the amp are most of the original 1950’s By varying the negative grid will produce Fender tweed amps such as the What is a valve? bias the technician can correctly an unbearable Deluxe and, of course, the Hopefully, a brief explanation will set up your amp for maximum distortion at all legendary Vox AC30.
    [Show full text]
  • ECE 255, MOSFET Basic Configurations
    ECE 255, MOSFET Basic Configurations 8 March 2018 In this lecture, we will go back to Section 7.3, and the basic configurations of MOSFET amplifiers will be studied similar to that of BJT. Previously, it has been shown that with the transistor DC biased at the appropriate point (Q point or operating point), linear relations can be derived between the small voltage signal and current signal. We will continue this analysis with MOSFETs, starting with the common-source amplifier. 1 Common-Source (CS) Amplifier The common-source (CS) amplifier for MOSFET is the analogue of the common- emitter amplifier for BJT. Its popularity arises from its high gain, and that by cascading a number of them, larger amplification of the signal can be achieved. 1.1 Chararacteristic Parameters of the CS Amplifier Figure 1(a) shows the small-signal model for the common-source amplifier. Here, RD is considered part of the amplifier and is the resistance that one measures between the drain and the ground. The small-signal model can be replaced by its hybrid-π model as shown in Figure 1(b). Then the current induced in the output port is i = −gmvgs as indicated by the current source. Thus vo = −gmvgsRD (1.1) By inspection, one sees that Rin = 1; vi = vsig; vgs = vi (1.2) Thus the open-circuit voltage gain is vo Avo = = −gmRD (1.3) vi Printed on March 14, 2018 at 10 : 48: W.C. Chew and S.K. Gupta. 1 One can replace a linear circuit driven by a source by its Th´evenin equivalence.
    [Show full text]
  • Bias Circuits for RF Devices
    Bias Circuits for RF Devices Iulian Rosu, YO3DAC / VA3IUL, http://www.qsl.net/va3iul A lot of RF schematics mention: “bias circuit not shown”; when actually one of the most critical yet often overlooked aspects in any RF circuit design is the bias network. The bias network determines the amplifier performance over temperature as well as RF drive. The DC bias condition of the RF transistors is usually established independently of the RF design. Power efficiency, stability, noise, thermal runway, and ease to use are the main concerns when selecting a bias configuration. A transistor amplifier must possess a DC biasing circuit for a couple of reasons. • We would require two separate voltage supplies to furnish the desired class of bias for both the emitter-collector and the emitter-base voltages. • This is in fact still done in certain applications, but biasing was invented so that these separate voltages could be obtained from but a single supply. • Transistors are remarkably temperature sensitive, inviting a condition called thermal runaway. Thermal runaway will rapidly destroy a bipolar transistor, as collector current quickly and uncontrollably increases to damaging levels as the temperature rises, unless the amplifier is temperature stabilized to nullify this effect. Amplifier Bias Classes of Operation Special classes of amplifier bias levels are utilized to achieve different objectives, each with its own distinct advantages and disadvantages. The most prevalent classes of bias operation are Class A, AB, B, and C. All of these classes use circuit components to bias the transistor at a different DC operating current, or “ICQ”. When a BJT does not have an A.C.
    [Show full text]
  • First-Order Circuits
    CHAPTER SIX FIRST-ORDER CIRCUITS Chapters 2 to 5 have been devoted exclusively to circuits made of resistors and independent sources. The resistors may contain two or more terminals and may be linear or nonlinear, time-varying or time-invariant. We have shown that these resistive circuits are always governed by algebraic equations. In this chapter, we introduce two new circuit elements, namely, two- terminal capacitors and inductors. We will see that these elements differ from resistors in a fundamental way: They are lossless, and therefore energy is not dissipated but merely stored in these elements. A circuit is said to be dynamic if it includes some capacitor(s) or some inductor(s) or both. In general, dynamic circuits are governed by differential equations. In this initial chapter on dynamic circuits, we consider the simplest subclass described by only one first-order differential equation-hence the name first-order circuits. They include all circuits containing one 2-terminal capacitor (or inductor), plus resistors and independent sources. The important concepts of initial state, equilibrium state, and time constant allow us to find the solution of any first-order linear time-invariant circuit driven by dc sources by inspection (Sec. 3.1). Students should master this material before plunging into the following sections where the inspection method is extended to include linear switching circuits in Sec. 4 and piecewise- linear circuits in Sec. 5. Here,-the important concept of a dynamic route plays a crucial role in the analysis of piecewise-linear circuits by inspection. l TWO-TERMINAL CAPACITORS AND INDUCTORS Many devices cannot be modeled accurately using only resistors.
    [Show full text]
  • Basic Electrical Engineering
    BASIC ELECTRICAL ENGINEERING V.HimaBindu V.V.S Madhuri Chandrashekar.D GOKARAJU RANGARAJU INSTITUTE OF ENGINEERING AND TECHNOLOGY (Autonomous) Index: 1. Syllabus……………………………………………….……….. .1 2. Ohm’s Law………………………………………….…………..3 3. KVL,KCL…………………………………………….……….. .4 4. Nodes,Branches& Loops…………………….……….………. 5 5. Series elements & Voltage Division………..………….……….6 6. Parallel elements & Current Division……………….………...7 7. Star-Delta transformation…………………………….………..8 8. Independent Sources …………………………………..……….9 9. Dependent sources……………………………………………12 10. Source Transformation:…………………………………….…13 11. Review of Complex Number…………………………………..16 12. Phasor Representation:………………….…………………….19 13. Phasor Relationship with a pure resistance……………..……23 14. Phasor Relationship with a pure inductance………………....24 15. Phasor Relationship with a pure capacitance………..……….25 16. Series and Parallel combinations of Inductors………….……30 17. Series and parallel connection of capacitors……………...…..32 18. Mesh Analysis…………………………………………………..34 19. Nodal Analysis……………………………………………….…37 20. Average, RMS values……………….……………………….....43 21. R-L Series Circuit……………………………………………...47 22. R-C Series circuit……………………………………………....50 23. R-L-C Series circuit…………………………………………....53 24. Real, reactive & Apparent Power…………………………….56 25. Power triangle……………………………………………….....61 26. Series Resonance……………………………………………….66 27. Parallel Resonance……………………………………………..69 28. Thevenin’s Theorem…………………………………………...72 29. Norton’s Theorem……………………………………………...75 30. Superposition Theorem………………………………………..79 31.
    [Show full text]
  • Chapter 4 BJT BIASING CIRCUIT Introduction – Biasing the Analysis Or Design of a Transistor Amplifier Requires Knowledge of Both the Dc and Ac Response of the System
    Chapter 4 BJT BIASING CIRCUIT Introduction – Biasing The analysis or design of a transistor amplifier requires knowledge of both the dc and ac response of the system. In fact, the amplifier increases the strength of a weak signal by transferring the energy from the applied DC source to the weak input ac signal The analysis or design of any electronic amplifier therefore has two components: •The dc portion and •The ac portion During the design stage, the choice of parameters for the required dc levels will affect the ac response. What is biasing circuit? Biasing: Application of dc voltages to establish a fixed level of current and voltage. Purpose of the DC biasing circuit • To turn the device “ON” • To place it in operation in the region of its characteristic where the device operates most linearly . •Proper biasing circuit which it operate in linear region and circuit have centered Q-point or midpoint biased •Improper biasing cause Improper biasing cause •Distortion in the output signal •Produce limited or clipped at output signal Important basic relationship IECB= II + I β = C I B IE =+≅ (β 1) IIBC VVVCB= CE − BE Operating Point •Active or Linear Region Operation Base – Emitter junction is forward biased Base – Collector junction is reverse biased Good operating point •Saturation Region Operation Base – Emitter junction is forward biased Base – Collector junction is forward biased •Cutoff Region Operation Base – Emitter junction is reverse biased BJT Analysis DC AC analysis analysis Calculate gains of the Calculate the DC Q-point amplifier
    [Show full text]
  • Chapter 2: Kirchhoff Law and the Thvenin Theorem
    Chapter 3: Capacitors, Inductors, and Complex Impedance Chapter 3: Capacitors, Inductors, and Complex Impedance In this chapter we introduce the concept of complex resistance, or impedance, by studying two reactive circuit elements, the capacitor and the inductor. We will study capacitors and inductors using differential equations and Fourier analysis and from these derive their impedance. Capacitors and inductors are used primarily in circuits involving time-dependent voltages and currents, such as AC circuits. I. AC Voltages and circuits Most electronic circuits involve time-dependent voltages and currents. An important class of time-dependent signal is the sinusoidal voltage (or current), also known as an AC signal (Alternating Current). Kirchhoff’s laws and Ohm’s law still apply (they always apply), but one must be careful to differentiate between time-averaged and instantaneous quantities. An AC voltage (or signal) is of the form: V(t) =Vp cos(ωt) (3.1) where ω is the angular frequency, Vp is the amplitude of the waveform or the peak voltage and t is the time. The angular frequency is related to the freguency (f) by ω=2πf and the period (T) is related to the frequency by T=1/f. Other useful voltages are also commonly defined. They include the peak-to-peak voltage (Vpp) which is twice the amplitude and the RMS voltage (VRMS) which is VVRMS = p / 2 . Average power in a resistive AC device is computed using RMS quantities: P=IRMSVRMS = IpVp/2. (3.2) This is important enough that voltmeters and ammeters in AC mode actually return the RMS values for current and voltage.
    [Show full text]
  • NORTHERN ENGINEER a Publication of the School of Engineering
    THE NORTHERN ENGINEER a publication of the school of engineering ""-·, • •• 4/ltlll .. Volume 23, Number 2 & 3 u NIVERSilY OF ALASKA FAIRBANKS .. Summer/Fall 1991 ADVISORY BOARD e are a reflection of our times. For THE NOKTHERN W ENGINEER, the University of Alaska, the State of Alaska, the Robert Boswell Lake & Boswell United States ofAmerica, and even the world as a whole, this is a time Fairbanks, AK of transition. The University of Alaska Fairbanks, of which THE AndrieChen NOKTHERN ENGINEER is a part, is undergoing a reorganization with Exxon Production the intent being to create a more streamlined, stronger entity, better Research Company Houston, TX able to meet the needs of our many constituencies. Mark Fryer Fryer/Pressley How will these changes affect THE NOKTHERN ENGINEER? Engineering, Inc. Anchorage, AK Well, one change has already occurred, Cynthia M. Owen left the Wilbur Haas University ofAlaska Fairbanks, effective June 30, 1992. This is the last Michigan Technological University issue that Mrs. Owen collaborated on--editing, proofing, Houghton, MI brainstorming. She contributed greatly to the quality of this publication Lee Leonard and will be sorely missed. U.S. Department of Energy Washington, DC The next part of this change will be the need for us to address the problems of THE NOKTHERN ENGINEER. We have been facing a Ed Link U.S.CRREL decline in paid subscribers, dijficulty in obtaining publishable technical Hanover,NH material and severe budgetary constraints. For all of these reasons, MikeMetz THE NORTHERN ENGINEER will temporarily suspend publication, Yukon Pacific Corporation effective the Winter 1991/Spring 1992 issue.
    [Show full text]
  • Linear Electronic Circuits and Systems Graham Bishop Beginning Basic P.E
    Linear Electronic Circuits andSystems Macmillan Basis Books in Electronics General Editor Noel M. Morris, Principal Lecturer, North Staffordshire Polytechnic Linear Electronic Circuits and Systems Graham Bishop Beginning Basic P.E. Gosling Continuing Basic P.E.Gosling Microprocessors and Microcomputers Eric Huggins Digital Electronic Circuits and Systems Noel M. Morris Electrical Circuits and Systems Noel M. Morris Microprocessor and Microcomputer Technology Noel M. Morris Semiconductor Devices Noel M. Morris Other related books Electrical and Electronic Systems and Practice Graham Bishop Electronics for Technicians Graham Bishop Digital Techniques Noel M. Morris Electrical Principles Noel M. Morris Essential Formulae for Electronic and Electrical Engineers: New Pocket­ Book Format Noel M. Morris Mastering Electronics John Watson Linear Electronic Circuits andSystems SECOND EDITION Graham Bishop Vice Principal Bridgwater College M MACMI LLAN PRESS LONDON © G. D. Bishop 1974, 1983 All rights reserved. No part of this publication may be reproduced or transmitted, in any form or by any means, without permission First edition 1974 Second edition 1983 Published by THE MACMILLAN PRESS LTD London and Basingstoke Companies and representatives throughout the world ISBN 978-0-333-35858-0 ISBN 978-1-349-06914-9 (eBook) DOI 10.1007/978-1-349-06914-9 Contents Foreword viii Preface to the First Edition ix Preface to the Second Edition xi 1 Signal processing 1 1.1 Voltages and currents 1 1.2 Transient responses 4 1.3 R-L-C transients 6 1.4 The d.c. restorer
    [Show full text]
  • 3510 33 P Department of Commerce
    This document is scheduled to be published in the Federal Register on 08/15/2017 and available online at https://federalregister.gov/d/2017-16904, and on FDsys.gov Billing Code: 3510 33 P DEPARTMENT OF COMMERCE Bureau of Industry and Security 15 CFR Parts 740, 772, and 774 [Docket No. 170309249-7249-01] RIN 0694-AH35 Wassenaar Arrangement 2016 Plenary Agreements Implementation AGENCY: Bureau of Industry and Security, Commerce. ACTION: Final rule. SUMMARY: The Bureau of Industry and Security (BIS) maintains, as part of its Export Administration Regulations (EAR), the Commerce Control List (CCL), which identifies certain items subject to Department of Commerce jurisdiction. This final rule revises the CCL, as well as corresponding parts of the EAR, to implement changes made to the Wassenaar Arrangement 1 List of Dual-Use Goods and Technologies (WA List) maintained and agreed to by governments participating in the Wassenaar Arrangement on Export Controls for Conventional Arms and Dual-Use Goods and Technologies (Wassenaar Arrangement, or WA) at the December 2016 WA Plenary meeting. The Wassenaar Arrangement advocates implementation of effective export controls on strategic items with the objective of improving regional and international security and stability. This rule harmonizes the CCL with the agreements reached at the 2016 Plenary meeting by revising Export Control Classification Numbers (ECCNs) controlled for national security reasons in each category of the CCL, as well as making other associated changes to the EAR. DATES: This rule is effective [INSERT DATE OF PUBLICATION IN THE FEDERAL REGISTER], except that: 1. the effective date for amendatory instruction 30 (ECCN 4A003 in Supplement No.
    [Show full text]
  • Transistor Biasing
    Transistor Biasing Transistor Biasing is the process of setting a transistors DC operating voltage or current conditions to the correct level so that any AC input signal can be amplified correctly by the transistor Transistor Biasing- S.Gayathri Priya 1 Need for Biasing A transistors steady state of operation depends a great deal on its base current, collector voltage, and collector current and therefore, if a transistor is to operate as a linear amplifier, it must be properly biased to have a suitable operating point. Establishing the correct operating point requires the proper selection of bias resistors and load resistors to provide the appropriate input current and collector voltage conditions. Transistor Biasing- S.Gayathri Priya 2 Q Point The correct biasing point for a bipolar transistor, either NPN or PNP, generally lies somewhere between the two extremes of operation with respect to it being either “fully-ON” or “fully- OFF” along its load line. This central operating point is called the “Quiescent Operating Point”, or Q-point for short. Transistor Biasing- S.Gayathri Priya 3 BJT Biasing methods The various types of biasing methods are: • Fixed Bias • Collector to base bias • Voltage divider bias Transistor Biasing- S.Gayathri Priya 4 Fixed Bias The transistors base current, IB remains constant for given values of Vcc, and therefore the transistors operating point must also remain fixed.Hence referred as fixed biasing Transistor Biasing- S.Gayathri Priya 5 Fixed Bias This two resistor biasing This type of transistor network is used to establish biasing arrangement is also the initial operating region of beta dependent biasing as the transistor using a fixed the steady-state condition of current bias.
    [Show full text]