Module 3: Electronics 2012-2013 Anne-Johan Annema Translation: Yoeri Bruinsma Lian Xi UNIVERSITEIT TWENTE. Contents 0 Introduction 7 0.1 Electronics ............................... 7 0.2 Electronic systems ........................... 8 0.3 A general electronic system . ...................... 8 0.4 Structure of the book .......................... 11 0.5 Preparatory knowledge for this book . ................ 13 0.5.1 Notation . ........................... 13 0.5.2 Linear components . ...................... 13 0.5.3 Independent sources ...................... 14 0.5.4 Controlled or independent sources ............... 14 0.5.5 Kirchhoff’s current and voltage laws . ........... 14 0.5.6 Superposition.......................... 15 0.5.7 Th´evenin and Norton equivalents ............... 17 0.5.8 Linear networks and signals . ................ 18 0.5.9 Fourier transformations ..................... 19 0.5.10 Differential equations ...................... 20 0.5.11 Circuit analysis methods .................... 21 0.5.12 Transfer functions . ...................... 24 0.5.13 Bode plots ........................... 26 0.5.14 Calculations & mathematics . ................ 28 0.5.15 Simplifying relations ...................... 30 0.6 Solving exercises . ........................... 31 0.6.1 Verification using the answer manual . ........... 33 0.7 And finally... ........................... 34 1 Models 35 1.1 Components ............................... 35 1.2 Analysing and modelling circuits .................... 40 1.3 Ideal diode model . ........................... 41 1.4 Diode models and time-independent circuits . ........... 45 1.5 Diode models and time-dependent circuits ............... 47 2 Summary of semiconductor physics 57 2.1 Introduction ............................... 57 2.2 Semiconductors . ........................... 58 2.3 Diodes . ................................. 61 1 2 CONTENTS 2.4 Bipolar junction transistors (BJTs) . ................ 62 2.5 MOS-transistors . ........................... 65 2.5.1 MOS-transistor in strong inversion ............... 68 2.5.2 MOS-transistor in strong inversion: summary ......... 69 2.5.3 MOS-transistor symbols .................... 71 3 Bias circuits 73 3.1 Introduction ............................... 73 3.1.1 Biasing a transistor: the bias point ............... 73 3.1.2 Biasing a transistor: requirements for its bias point . ..... 75 3.1.3 Biasing a transistor . ...................... 75 3.2 Biasing a BJT . ........................... 77 3.3 Biasing a MOS-transistor . ...................... 83 4 Small-signal equivalent circuits 87 4.1 Introduction ............................... 87 4.2 Linear model for transistors . ...................... 88 4.2.1 SSEC of a BJT . ...................... 90 4.2.2 SSEC of a MOS transistor . ................ 92 4.2.3 Small-signal parameters .................... 94 4.3 Amplifier circuits . ........................... 96 4.3.1 Coupling the input and output . ................ 96 4.3.2 SSEC of a basic amplifier circuit ................ 98 5 Amplifier circuits 103 5.1 Introduction ............................... 103 5.1.1 The common-base circuit, CBC ................ 106 5.1.2 The common-gate circuit, CGC ................ 108 5.1.3 The common-collector circuit, CCC . ........... 109 5.1.4 The common-drain circuit, CDC ................ 111 5.1.5 CEC, CBC, CCC, CSC, CGC and CDC: a comparison .... 113 5.2 Cascade of multiple amplifiers ..................... 114 5.2.1 Voltage source . ...................... 115 5.2.2 Current source . ...................... 115 5.2.3 Current mirror . ...................... 116 6 Feedback 119 6.1 Introduction ............................... 119 6.2 Negative feedback . ........................... 120 6.2.1 Full negative feedback: a first concept . ........... 121 6.2.2 Partial negative feedback: a generalised concept . ..... 123 6.3 Negative feedback and amplifiers: some examples ........... 124 6.3.1 Effect of negative feedback on bandwidth ........... 124 6.3.2 Effect of negative feedback on interference and noise ..... 126 6.3.3 Effect of negative feedback on nonlinear distortion . ..... 126 6.4 Stability ................................. 127 6.4.1 Rough classification of systems with feedback . ..... 128 CONTENTS 3 6.4.2 Stability of systems with negative feedback .......... 129 6.4.3 Stable and unstable: now what? ................ 129 6.4.4 Stability of systems with feedback: examples ......... 131 6.4.5 Phase and gain margin ..................... 135 6.4.6 Positive feedback: peaking . ................ 139 6.4.7 The Bode plot as tool for presentation . ........... 140 6.5 Feedback and dominant first-order behavior . ........... 142 6.5.1 Creating dominant first-order behavior . ........... 143 7 The op-amp and negative feedback 145 7.1 Introduction ............................... 145 7.2 Linear applications ........................... 146 7.2.1 Non-inverting voltage amplifier ................ 146 7.2.2 Inverting voltage amplifier . ................ 149 7.2.3 Virtual ground . ...................... 152 7.2.4 The integrator .......................... 154 7.2.5 The differentiator . ...................... 155 7.2.6 Summation of currents ..................... 156 7.2.7 Summation of voltages ..................... 157 7.2.8 Subtraction of voltages ..................... 158 7.2.9 Filters . ........................... 159 7.3 Feedback with non-linear elements . ................ 160 7.3.1 Logarithmic conversion .................... 160 7.3.2 Exponential converters ..................... 161 7.4 Op-amp non-idealities . ...................... 162 7.4.1 Frequency-dependent gain . ................ 162 7.4.2 First-order behavior and slew rate ............... 162 8 Positive feedback: oscillators 165 8.1 Harmonic oscillators with a low Q . ................ 168 8.1.1 General introduction ...................... 169 8.1.2 Wien bridge oscillator ..................... 170 8.1.3 Phase-shift oscillators ..................... 172 8.1.4 Startup conditions . ...................... 175 8.2 Harmonic oscillators with higher Q . ................ 178 8.2.1 Single transistor oscillators . ................ 178 8.2.2 Crystal oscillators . ...................... 188 9 Basic internal circuits for op amps 191 9.1 Introduction ............................... 191 9.2 The input stage . ........................... 193 9.2.1 Symmetry requirement ..................... 194 9.2.2 First implementation: large signal behaviour ......... 194 9.2.3 Second (or actual) implementation: large signal behaviour . 196 9.2.4 Small signal behaviour ..................... 199 9.2.5 Small signal behaviour with a non-ideal current source .... 201 9.3 From input stage to intermediate stage . ................ 205 4 CONTENTS 9.4 Intermediate stages ........................... 209 9.5 Output stages . ........................... 215 9.5.1 Requirements for the output stage ............... 215 9.5.2 Simple output stages ...................... 216 9.5.3 Slightly less simple output stages ............... 219 9.5.4 Power efficiency aspects of output stages ........... 223 9.6 Frequency dependencies . ...................... 227 9.6.1 Bandwidth limitations: small signal . ........... 227 9.6.2 Bandwidth limitations: large signal . ........... 231 10 Introduction to RF electronics 233 10.1 Introduction ............................... 233 10.2 Transmitting and receiving . ...................... 234 10.3 Maxwell ................................. 237 10.3.1 Maxwell and Kirchhoff ..................... 237 10.4 Introduction to antennae . ...................... 240 10.5 Dipole antennae . ........................... 248 10.6 Monopole antennae ........................... 250 10.7 Other antenna characteristics ...................... 251 10.8 A transmission system, a bit more exact ................ 252 10.9 In addition ................................ 252 10.9.1 Impedance matching and maximum power transfer . ..... 253 10.9.2 Fourier transformations, FFT and more . ........... 254 11 Digital Circuits 257 11.1 Introduction ............................... 257 11.2 Designing logical building blocks . ................ 258 11.2.1 Basic logic ports . ...................... 258 11.2.2 The relation between “high” (digital) and “high” (analog) . 258 11.3 Old solutions: DL, DTL and TTL . ................ 260 11.3.1 Diode logic ........................... 260 11.3.2 Diode-transistor and transistor-transistor logic ......... 260 11.4 NMOS and PMOS logic . ...................... 262 11.4.1 From TTL to NMOS ...................... 262 11.4.2 The analog linear amplifier . ................ 262 11.4.3 A digital (saturated) amplifier . ................ 262 11.4.4 Arbitrary functions with NMOS logic . ........... 264 11.4.5 The PMOS alternative ..................... 265 11.5 The current solution: CMOS implementation . ........... 266 11.6 The loading of a port .......................... 268 11.6.1 Comparing power consumption ................ 270 11.7 Choosing the supply voltage ...................... 272 11.7.1 Scaling . ........................... 272 11.7.2 Transistor scaling and supply voltage . ........... 273 11.8 Speed . ................................. 275 11.8.1 Definitions of parameters .................... 277 11.9 The latch ................................ 278 CONTENTS 5 11.9.1 Signal retention . ...................... 278 Bibliography 281 Index 283 6 CONTENTS Chapter 0 Introduction 0.1 Electronics In our everyday life, we are being surrounded by more and more electronic devices, containing more and more electronic circuitry. Because of this increase