Page 9 - Basics of Electrical, Electronic and Communication
P. 9

CONTENTS                                                   xv


                     12 Amplifiers and Oscillators                              193
                        12.1 Principle of electronic amplifiers . . . . . . . . . . . . 193
                        12.2 Characteristics of an amplifier . . . . . . . . . . . . . 194
                             12.2.1 Gain . . . . . . . . . . . . . . . . . . . . . . . 195
                             12.2.2 Input resistance . . . . . . . . . . . . . . . . . 196
                             12.2.3 Output resistance . . . . . . . . . . . . . . . . 197
                             12.2.4 Equivalent circuit of an amplifier . . . . . . . . 197
                        12.3 Classification of amplifiers . . . . . . . . . . . . . . . 201
                        12.4 Frequency response of amplifier . . . . . . . . . . . . 202
                        12.5 Noise . . . . . . . . . . . . . . . . . . . . . . . . . . 203
                             12.5.1 Signal-to-noise ratio . . . . . . . . . . . . . . 205
                        12.6 Cascaded amplifiers . . . . . . . . . . . . . . . . . . . 205
                        12.7 Differential amplifiers . . . . . . . . . . . . . . . . . . 206
                        12.8 Concept of open loop and closed loop . . . . . . . . . 208
                        12.9 The operational amplifier . . . . . . . . . . . . . . . . 209
                             12.9.1 The ideal op-amp . . . . . . . . . . . . . . . . 211
                             12.9.2 Equivalent circuit of op-amp . . . . . . . . . . 211
                             12.9.3 Parameters of op-amp . . . . . . . . . . . . . 212
                        12.10Basic op-amp circuits . . . . . . . . . . . . . . . . . . 214
                             12.10.1 Non-inverting amplifier . . . . . . . . . . . . . 216
                        12.11Feedback systems . . . . . . . . . . . . . . . . . . . . 217
                        12.12Feedback in amplifiers . . . . . . . . . . . . . . . . . 217
                             12.12.1 The effects of negative feedback . . . . . . . . 220
                             12.12.2 Stabilization of gain with negative feedback . . 221
                             12.12.3 Frequency response and bandwidth . . . . . . 221
                             12.12.4 Effects of negative feedback on impedance . . 222
                             12.12.5 Reduction in distortion with negative feedback 223
                             12.12.6 Noise . . . . . . . . . . . . . . . . . . . . . . 223
                             12.12.7 Decrease in gain . . . . . . . . . . . . . . . . 223
                        12.13Oscillators . . . . . . . . . . . . . . . . . . . . . . . . 224
                        12.14Principle of oscillators . . . . . . . . . . . . . . . . . 224
                        12.15RC oscillators . . . . . . . . . . . . . . . . . . . . . . 227
                             12.15.1 Phase shift oscillator . . . . . . . . . . . . . . 228
                             12.15.2 Wien bridge oscillator . . . . . . . . . . . . . 229
                        12.16LC oscillators . . . . . . . . . . . . . . . . . . . . . . 230
                             12.16.1 Hartely oscillator . . . . . . . . . . . . . . . . 231
                             12.16.2 Colpitts oscillator . . . . . . . . . . . . . . . . 232



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