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Basic Oscillator Model - RF and Microwave Engineering - Lecture Slides, Slides of Electronics engineering

Bharat Ratna Dr. B. R. Ambedkar UniversityElectronics engineering

These are the Lecture Slides of RF and Microwave Engineering which includes Design, Parameters, Data Used, Matching Design, Data, Result, Configure Library, Add Components, List etc. Key important points are: Basic Oscillator Model, Oscillator, Selected Frequency, Barkhausen Criteria Implies, Transfer Functions, Feedback Stage, Open Loop Amplifier, Barkhausen Criteria, Loop Gain Equation, Oscillators

Typology: Slides

2012/2013

Uploaded on 03/23/2013

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Basic Oscillator Model
• Oscillator has positive feedback loop at
selected frequency
• Barkhausen criteria implies that the
multiplication of the transfer functions of
open loop amplifier and feedback stage is
HF (
ω
)HA (
ω
) = 1
• Barkhausen criteria aka loop gain equation
Docsity.com
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Download Basic Oscillator Model - RF and Microwave Engineering - Lecture Slides and more Slides Electronics engineering in PDF only on Docsity!

Basic Oscillator Model

• Oscillator has positive feedback loop at

selected frequency

• Barkhausen criteria implies that the

open loop amplifier and feedback stage ismultiplication of the transfer functions of

H

F

H

A

• Barkhausen criteria aka loop gain equation

LC Oscillators – Lower RF Frequencies

LC Oscillators – Lower RF Frequencies

• Can also design with BJTs.

High RF & Microwave Oscillators

• Take advantage of our knowledge of

stability

• Rollett Stability Factor

k

Creating Oscillator Condition

• Frequently begin with common-base or

common-gate configuration

• Convert common-emitter s-parameters to

common-base (similarly for FETs)

• Add inductor in series with base (or gate)

unstable Rollett factoras positive feedback loop network to attain

k

Unstable Condition – Oscillation

common-base [Convert transistor

s ]

to [

Z ] tr

[

Z

]

L (^) =

[

Z

]

Osc = [

Z ] L +[ Z ] tr

Convert [

Z

]

Osc

(^) to

[

s ] Osc

circlesPlot stability

1 1

1 1

j L

ω

Unstable Transistor Oscillator Design

Select potentially unstable transistor at freq

Select appropriate transistor configuration

Draw output stability circle in

L

plane

Select appropriate value of

L

to produce largest

yielding |possible negative resistance at input of transistor

L

| >1 and

Z

in

circuit was a one-port oscillator bySelect source tuning impedance Zs as if the

R

S

R

IN

typically

R

S

R

IN

R

IN

< 0 and

X

S

X

IN

with lumped or distributed elementsDesign source tuning and terminating networks

Dielectric Resonator Oscillator (DRO)

Varactor Diodes (Voltage Variable Caps)

Gunn Elements For Oscillators

Mixer Basics

Heterodyne receiver system incorporating a mixer.

frequencies at the output of the system. Basic mixer concept: two input frequencies are used to create new

Mixing Process Spectrum

Compression Point and 3

rd

Order Intercept

Single-Ended BJT Mixer