Unit –III Waveform Generators -14 Marks

Course Outcome Use BJT as Waveform Generator

Introduction to Oscillators: “An amplifier with positive feedback acts as an oscillator”. . AEI403.23

Definition : “An oscillator is just an electronic circuit which converts dc energy into ac energy of required frequency”. Or “An oscillator is an electronic circuit which produces an ac output without any input”. AEI-403.24

Classification of Oscillators RC Oscillator RC phase shift Wein Bridge Oscillator LC Oscillator Hartley Colpitts Clapp Crystal Oscillator

Bakhausen Criteria

Bakhausen Criteria

RC Phase Shift Oscillator

At some particular frequency fo,the phase shift of each section is 60º,so that the total phase-shift produced by the RC network is (3*60º)=180º. The frequency of oscillations is given by 1 f  2RC 6 Where R1=R2=R3=R C1=C2=C3=C.

Pierce Crystal oscillator

Miller Crystal Oscillator

Miller Sweep Generator

Bootstrap Sweep Generator