Chapter 12 Signal generators andwaveform-shaping circuitsIntroduction12.1 Basic principles of sinusoidal oscillators12.2 RC oscillator circuits12.3 LC and crystal oscillators12.4 Bistable Multivibrators12.5 Generation of a standardized pulse-Themonostable multivibratorMicroelectronicCircuits
Microelectronic Circuits Chapter 12 Signal generators and waveform-shaping circuits Introduction 12.1 Basic principles of sinusoidal oscillators 12.2 RC oscillator circuits 12.3 LC and crystal oscillators 12.4 Bistable Multivibrators 12.5 Generation of a standardized pulse-The monostable multivibrator
Introduction(1)linear oscillators:employsapositive-feedbackloopconsistingofanamplifierandanRCorLCfrequency-selectivenetwork.(Section13.1-3)Thetwo(2)nonlinear oscillators or functiondifferentgenerators:approachesThe bistable multivibrator(Section 13.4)theastablemultivibrator (Section13.5)themonostablemultivibrator(Section13.6)MicroelectronicCircuits
Microelectronic Circuits Introduction The two different approaches (1)linear oscillators: employs a positive-feedback loop consisting of an amplifier and an RC or LC frequency-selective network. (Section 13.1-3) (2)nonlinear oscillators or function generators: • The bistable multivibrator(Section 13.4) • the astable multivibrator (Section 13.5) • the monostable multivibrator(Section 13.6)
The basic structure of sinusoidaloscillatorsAmplifier circuit:realize the energy controlFrequency-selectivenetwork:oscillatorThebasicfrequency is determinedstructureX, =XfPositive feedback loop:amplitude control : implementation of thenonlinear amplitude-stabilization mechanismMicroelectronicCircuits
Microelectronic Circuits The basic structure of sinusoidal oscillators The basic structure Amplifier circuit：realize the energy control Frequency-selective network：oscillator frequency is determined Positive feedback loop： amplitude control ：implementation of the nonlinear amplitude-stabilization mechanism i f x = x
Basic Principles of SinusoidalOscillatorThe oscillator feedback loopAmplifierAFrequency-selectivenetworkβThe basic structure of a sinusoidal oscillator.Apositive-feedbackloopisformedbyanamplifier and a frequency-selective networkMicroelectronic Circuits
Microelectronic Circuits Basic Principles of Sinusoidal Oscillator ⚫ The oscillator feedback loop ⚫ The basic structure of a sinusoidal oscillator. ⚫ A positive-feedback loop is formed by an amplifier and a frequency-selective network
Basic Principles of SinusoidalOscillator Feedback signal X,is summed with apositive signThe gain-with-feedback isF:1模电课件\动摄品的产生exeA(s)Af(S)1- A(s)β(s)The oscillation criterion: Barkhausencriterion.L(jo) = A(joo)β(jo) = lPA+P=2nπMicroelectronic Circuits
Microelectronic Circuits Basic Principles of Sinusoidal Oscillator ⚫ Feedback signal xf is summed with a positive sign ⚫ The gain-with-feedback is ⚫ The oscillation criterion: Barkhausen criterion. 1 ( ) ( ) ( ( ) A s s A s A s f − = ） n L j A j j A 2 ( 0 ) ( 0 ) ( 0 ) 1 + = = =