RF Components and Circuits

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1 RF Components and Circuits

3 RF Components and Circuits Joseph J. Carr Newnes OXFORD AMSTERDAM BOSTON LONDON NEW YORK PARIS SAN DIEGO SAN FRANCISCO SINGAPORE SYDNEY TOKYO

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.

4 Newnes An imprint of Elsevier Science Linacre House, Jordan Hill, Oxford OX2 8DP 225 Wildwood Avenue, Woburn, MA First edition 2002 Copyright Joseph J. Carr and Elsevier Science Ltd 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 Published in conjunction with Radio Society of Great Britain, Lambda House, Cranborne Road, Potters Bar, Herts, EN6 3JE. 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

5 Foreword...? Remembering Joe Carr, K4IPV...? Preface...? Part 1 Introduction Introduction to radio frequencies... 1 What are the radio frequencies?... 1 Why are radio frequencies different?... 1 What this book covers 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 Transient signals Sampled signals Noise Signal-to-noise ratio (SNR or Sn) Noise factor, noise figure and noise temperature Noise factor (FN) Noise figure (NF) Noise temperature ( Te) Noise in cascade amplifiers Noise reduction strategies Noise reduction by signal averaging Example Radio receivers... 3 Signals, noise and reception... 3 The reception problem Strategies Radio receiver specifications Origins Crystal video receivers Tuned radio frequency (TRF) receivers

6 Superheterodyne receivers Heterodyning Front-end circuits Intermediate frequency (IF) amplifier Detector Audio amplifiers Receiver performance factors Units of measure Input signal voltage dbm dbmv db V Noise Signal-to-noise ratio (SNR or Sn) Receiver noise floor Static measures of receiver performance Sensitivity Selectivity Front-end bandwidth Image rejection st IF rejection IF bandwidth IF passband shape factor Distant frequency ( ultimate ) rejection Stability AGC range and threshold Dynamic performance Intermodulation products db compression point Third-order intercept point Dynamic range Blocking Cross-modulation Reciprocal mixing IF notch rejection Internal spurii Part 2 Circuits RF amplifiers... 4 Noise and preselectors/preamplifiers... 70

7 Amplifier configurations Transistor gain Classification by common element Common emitter circuits Common collector circuits Common base circuits Transistor biasing Collector-to-base bias Emitter bias or self-bias Frequency characteristics JFET and MOSFET connections JFET preselector VHF receiver preselector MOSFET preselector Voltage-tuned receiver preselector Broadband RF preamplifier for VLF, LF and AM BCB Push-pull RF amplifiers Types of push-pull RF amplifiers Actual circuit details Broadband RF amplifier (50 ohm input and output) Mixers Linear-vs-non-linear mixers Simple diode mixer The question of balance Unbalanced mixers Single balanced mixers Double balanced mixers Spurious responses Image Half IF IF feedthrough High-order spurs LO harmonic spurs LO noise spurs Mixer distortion products Third-order intercept point Calculating intercept points Mixer losses Noise figure Noise balance Single-ended active mixer circuits

8 Balanced active mixers Gilbert cell mixers Passive double-balanced mixers Diplexers Bandpass diplexers Double DBM Image reject mixers VHF/UHF microwave mixer circuits Oscillators... 6 Feedback oscillators... 6 General types of RF oscillator circuits Piezoelectric crystals Piezoelectricity Equivalent circuit Crystal packaging Temperature performance Room temperature crystal oscillators Temperature-compensated crystal oscillators Oven-controlled crystal oscillators Short-term stability Long-term stability Miller oscillators Pierce oscillators Butler oscillators Colpitts oscillators Overtone oscillators Frequency stability Temperature Thermal isolation Avoid self-heating Other stability criteria Use low frequencies Feedback level Output isolation DC power supply Vibration isolation Coil core selection Coil-core processing Air core coils Capacitor selection Tempco circuit

9 Varactors Frequency synthesizers Reference section Frequency synthesizer section Output section Automatic level control (ALC) IF amplifiers and filters... 7 IF filters: general filter theory... 7 L C IF filters Crystal filters Crystal ladder filters Monolithic ceramic crystal filters Mechanical filters SAW filters Filter switching in IF amplifiers Amplifier circuits Cascode pair amplifier Universal IF amplifier Coupling to block filters More IC IF amplifiers MC-1590 circuit SL560C circuits FM IF amplifier Successive detection logarithmic amplifiers Demodulators AM envelope detectors AM noise Synchronous AM demodulation Double sideband (DSBSC) and single sideband (SSBSC) suppressed carrier demodulators Phasing method FM and PM demodulator circuits Foster Seeley discriminator Ratio detector Pulse counting detector Phase-locked loop FM/PM detectors Quadrature detector Part 3 Components... 3

10 9 Capacitors... 9 Units of capacitance... 9 Breakdown voltage Circuit symbols for capacitors Fixed capacitors Paper dielectric capacitors Mylar dielectric capacitors Ceramic dielectric capacitors Mica dielectric capacitors Other capacitors Variable capacitors Air variable main tuning capacitors Capacitor tuning laws SLC-vs-SLF Special variable capacitors Split stator capacitors Differential capacitors Transmitting variable capacitors Variable capacitor cleaning note Using and stabilizing a varactor diode Varactor tuning circuits Temperature compensation Varactor applications Inductors... C Inductor circuit symbols... C Inductance and inductors Inductance of a single straight wire Combining two or more inductors Air-core inductors Solenoid wound air-core inductors Adjustable coils Winding your own coils Amidon Associates coil system Using ferrite and powdered iron cores Materials used in cores Powdered iron Ferrite materials Making the calculations Toroid cores

Introduction Introduction to radio frequencies p. 3 What are the 'radio frequencies'? p. 3 Why are radio frequencies different? p.

Foreword p. xi Preface p. xiii Introduction Introduction to radio frequencies p. 3 What are the 'radio frequencies'? p. 3 Why are radio frequencies different? p. 3 What this book covers p. 3 Signals and