RF Components and Circuits RF Components and Circuits Joseph J. Carr Newnes O XFORD A MSTERDAM B OSTON L ONDON N EW Y ORK P ARIS S AN D IEGO S AN F RANCISCO S INGAPORE S YDNEY T OKYO Newnes An imprint of Elsevier Science Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA 01801-2041 First edition 2002 Copyright © Joseph J. Carr and Elsevier Science Ltd 2002. All rights reserved The right of Joseph J. Carr to be identified as the author of this work has been asserted in accordance with the Copyright, Designs and Patents Act 1988 No part of this publication may be reproduced in any material form (including photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by the Copyright Licensing Agency Ltd, 90 Tottenham Court Road, London, England W1T 4LP. Applications for the copyright holder’s written permission to reproduce any part of this publication should be addressed to the publishers British Library Cataloguing in Publication Data A catalogue record for this book is available from the British Library ISBN 0 7506 48449 Published in conjunction with Radio Society of Great Britain, Lambda House, Cranborne Road, Potters Bar, Herts, EN6 3JE. UK www.rsgb.org.uk For information on all Newnes publications visit our website at: newnespress.com Cover illustration supplied by Coilcraft Europe Ltd Composition by Genesis Typesetting, Rochester, Kent Printed and bound in Great Britain Foreword ? Remembering Joe Carr, K4IPV ? Preface ? Part 1 Introduction 1 1 Introduction to radio frequencies 1 What are the ’radio frequencies’? 1 Why are radio frequencies different? 1 What this book covers 1 2 Signals and noise 2 Types of signals 2 Static and quasistatic signals 2 Periodic signals 2 Repetitive signals 2 Transient signals and pulse signals 9 Fourier series 9 Waveform symmetry 11 Transient signals 17 Sampled signals 18 Noise 21 Signal-to-noise ratio (SNR or Sn) 27 Noise factor, noise figure and noise temperature 29 Noise factor (FN) 29 Noise figure (NF) 30 Noise temperature ( Te) 30 Noise in cascade amplifiers 31 Noise reduction strategies 31 Noise reduction by signal averaging 32 Example 32 3 Radio receivers 3 Signals, noise and reception 3 The reception problem 35 Strategies 37 Radio receiver specifications 38 Origins 38 Crystal video receivers 3.4 Tuned radio frequency (TRF) receivers 3.4 Superheterodyne receivers 3.4 Heterodyning 42 Front-end circuits 44 Intermediate frequency (IF) amplifier 44 Detector 44 Audio amplifiers 44 Receiver performance factors 44 Units of measure 45 Input signal voltage 45 dBm 45 dBmV 46 dB 46 V 46 Noise 46 Signal-to-noise ratio (SNR or Sn) 46 Receiver noise floor 47 Static measures of receiver performance 47 Sensitivity 47 Selectivity 50 Front-end bandwidth 52 Image rejection 53 1st IF rejection 54 IF bandwidth 54 IF passband shape factor 55 Distant frequency (’ultimate’) rejection 57 Stability 57 AGC range and threshold 58 Dynamic performance 58 Intermodulation products 59 -1 dB compression point 60 Third-order intercept point 60 Dynamic range 62 Blocking 63 Cross-modulation 63 Reciprocal mixing 64 IF notch rejection 64 Internal spurii 65 Part 2 Circuits 2 4 RF amplifiers 4 Noise and preselectors/preamplifiers 70 Amplifier configurations 70 Transistor gain 70 Classification by common element 72 Common emitter circuits 72 Common collector circuits 73 Common base circuits 73 Transistor biasing 73 Collector-to-base bias 74 Emitter bias or ˛self-bias 74 Frequency characteristics 75 JFET and MOSFET connections 75 JFET preselector 76 VHF receiver preselector 79 MOSFET preselector 79 Voltage-tuned receiver preselector 81 Broadband RF preamplifier for VLF, LF and AM BCB 81 Push-pull RF amplifiers 84 Types of push-pull RF amplifiers 84 Actual circuit details 86 Broadband RF amplifier (50 ohm input and output) 88 5 Mixers 5.1 Linear-vs-non-linear mixers 5.1 Simple diode mixer 94 The question of ˛balance 95 Unbalanced mixers 95 Single balanced mixers 95 Double balanced mixers 95 Spurious responses 95 Image 95 Half IF 96 IF feedthrough 96 High-order spurs 97 LO harmonic spurs 98 LO noise spurs 98 Mixer distortion products 98 Third-order intercept point 99 Calculating intercept points 101 Mixer losses 101 Noise figure 102 Noise balance 102 Single-ended active mixer circuits 103 Balanced active mixers 104 Gilbert cell mixers 113 Passive double-balanced mixers 114 Diplexers 116 Bandpass diplexers 117 Double DBM 5.36 Image reject mixers 5.36 VHF/UHF microwave mixer circuits 124 6 Oscillators 6 Feedback oscillators 6 General types of RF oscillator circuits 126 Piezoelectric crystals 128 Piezoelectricity 129 Equivalent circuit 129 Crystal packaging 129 Temperature performance 133 Room temperature crystal oscillators 133 Temperature-compensated crystal oscillators 133 Oven-controlled crystal oscillators 133 Short-term stability 134 Long-term stability 134 Miller oscillators 134 Pierce oscillators 136 Butler oscillators 138 Colpitts oscillators 143 Overtone oscillators 145 Frequency stability 147 Temperature 149 Thermal isolation 149 Avoid self-heating 150 Other stability criteria 150 Use low frequencies 150 Feedback level 150 Output isolation 150 DC power supply 150 Vibration isolation 153 Coil core selection 153 Coil-core processing 153 Air core coils 154 Capacitor selection 154 Tempco circuit 155 Varactors 155 Frequency synthesizers 157 Reference section 159 Frequency synthesizer section 159 Output section 159 Automatic level control (ALC) 160 7 IF amplifiers and filters 7 IF filters: general filter theory 7 L C IF filters 163 Crystal filters 165 Crystal ladder filters 167 Monolithic ceramic crystal filters 170 Mechanical filters 170 SAW filters 171 Filter switching in IF amplifiers 173 Amplifier circuits 174 Cascode pair amplifier 175 ˛Universal IF amplifier 175 Coupling to block filters 178 More IC IF amplifiers 179 MC-1590 circuit 179 SL560C circuits 180 FM IF amplifier 180 Successive detection logarithmic amplifiers 180 8 Demodulators 8.2 AM envelope detectors 8.2 AM noise 190 Synchronous AM demodulation 190 Double sideband (DSBSC) and single sideband (SSBSC) suppressed carrier demodulators 190 Phasing method 197 FM and PM demodulator circuits 197 Foster Seeley discriminator 197 Ratio detector 200 Pulse counting detector 8.23 Phase-locked loop FM/PM detectors 206 Quadrature detector 206 Part 3 Components 3 9 Capacitors 9 Units of capacitance 9 Breakdown voltage 211 Circuit symbols for capacitors 211 Fixed capacitors 212 Paper dielectric capacitors 212 Mylar dielectric capacitors 212 Ceramic dielectric capacitors 213 Mica dielectric capacitors 214 Other capacitors 214 Variable capacitors 215 Air variable main tuning capacitors 217 Capacitor tuning laws  SLC-vs-SLF 219 Special variable capacitors 220 Split stator capacitors 221 Differential capacitors 221 ˛Transmitting variable capacitors 222 Variable capacitor cleaning note 222 Using and stabilizing a varactor diode 223 Varactor tuning circuits 223 Temperature compensation 9.21 Varactor applications 230 10 Inductors C Inductor circuit symbols C Inductance and inductors 233 Inductance of a single straight wire 234 Combining two or more inductors 235 Air-core inductors 236 Solenoid wound air-core inductors 237 Adjustable coils 237 Winding your own coils 239 Amidon Associates coil system 239 Using ferrite and powdered iron cores 240 Materials used in cores 240 Powdered iron 241 Ferrite materials 242 Making the calculations 242 Toroid cores 244 [...]... 266 11 Tuning and matching 11 Vectors for RF circuits L C resonant tank circuits 11 270 Series resonant circuits Parallel resonant circuits 270 271 Tuned RF/ IF transformers Construction of RF/ IF transformers Bandwidth of RF/ IF transformers Choosing component values for L C resonant tank circuits The tracking problem The RF amplifier/antenna... RF Components and Circuits circuit They also include examples of many of the individual RF circuits we will be looking at So Part 1 is an introduction It is hard to say very much about RF circuits without talking about the components, but the special RF components don’t make much sense unless you already know something about the circuits So which should come first? (Think of chickens and eggs!) The... principal difference between repetitive and periodic signals is 6 RF Components and Circuits +V V1 0V T TIME A Figure 2.1 Various types of signal: (A) static +V V1 0V T TIME B Figure 2.1 (B) quasistatic Signals and noise 7 +V T V1 VT1 = VT2 = V1 T = T2 – T1 0V T T2 T1 TIME C Figure 2.1 (C) periodic +V V1 0V T TIME D Figure 2.1 (D) quasiperiodic 8 RF Components and Circuits +V V1 NOISE 0V T TIME E Figure... Now, let’s get started 2 Signals and noise Types of signals The nature of signals, and their relationship to noise and interfering signals, determines appropriate design all the way from the system level down to the component selection level In this chapter we will take a look at signals and noise, and how each affects the design of amplification and other RF circuits Signals can be categorized... Joe’s family, friends and colleagues We would also like to acknowledge with thanks the work undertaken by Dave Kimber to prepare the manuscript for publication Matthew Deans Newnes Publisher Preface This is a book on radio frequency (RF) circuits RF circuits are different from other circuits because the values of stray or distributed capacitances and inductances become significant at RF When circuit values... parasitic capacitances and inductances Conclusion 347 350 15 RF power measurement 15 Power units Types of RF power measurement Methods for measuring RF power Thermistor RF power meters 15 15 352 352 Bolometers Self-balancing bridge instruments Thermocouple RF power meters 353 355 356 Diode detector RF power meters 358 Circuits 360... that Joe’s life, work, and loving spirit enriched many lives is an understatement indeed A relentless communicator, both through the written word and through Amateur Radio, Joe redefined the word ‘prolific’ with 1,000 or more published articles and papers and nearly 100 books on topics ranging from science and technology to matters of history and faith Like his colleagues, family, and innumerable friends,... practical systems a much less than infinite 12 RF Components and Circuits Figure 2.4 Square wave bandwidth is found, so some of those harmonics will be removed by the normal action of the electronic circuits Also, it is sometimes found that higher harmonics might not be truly significant, so can be ignored As n becomes larger, the amplitude coefficients an and bn tend to become smaller At some point,... circuits 360 Micromatch Monomatch 15.12 363 The Bird Thruline sensor Calorimeters 364 366 Substitution flow calorimeters Absolute flow calorimeters 367 367 Micropower and low power measurements Error and uncertainty sources 370 372 Mismatch loss and mismatch uncertainty 372 16 Filtering against EMI/ RFI 16 Shielding Filter circuits. .. is to put circuits in Part 2 and components in Part 3, but then think of them as running in parallel rather than one after the other So you can swap between them, but because this is a paper-based book we have to print Part 3 after Part 2 Part 2 looks at the various types of RF circuits in roughly the order a radio signal sees them as it goes through a normal superhet receiver Many of these circuits . RF Components and Circuits RF Components and Circuits Joseph J. Carr Newnes O XFORD A MSTERDAM B OSTON L ONDON N EW Y ORK P ARIS S AN D IEGO S AN F RANCISCO S INGAPORE S YDNEY T OKYO Newnes An. Tuning and matching 11 Vectors for RF circuits 11 L C resonant tank circuits 270 Series resonant circuits 270 Parallel resonant circuits 271 Tuned RF/ IF transformers 273 Construction of RF/ IF. performance 47 Sensitivity 47 Selectivity 50 Front-end bandwidth 52 Image rejection 53 1st IF rejection 54 IF bandwidth 54 IF passband shape factor 55 Distant frequency (’ultimate’) rejection