L03 Oscillators
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Transcript of L03 Oscillators
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Ref:061031 EE3110 Oscillator 1
Lecture 3 Oscillator
Introduction of Oscillator
Linear Oscillator
Wien rid!e Oscillator
R" #$ase%&$ift Oscillator
L" Oscillator
&ta'ilit(
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Ref:061031 EE3110 Oscillator )
Oscillators
Oscillation:an effect t$at re*eatedl( and
re!ularl( fluctuates a'out t$e +ean ,alue
Oscillator:circuit t$at *roduces oscillation
"$aracteristics:-a,e%s$a*e. fre/uenc(.
a+*litude. distortion. sta'ilit(
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Ref:061031 EE3110 Oscillator 3
**lication of Oscillators
Oscillators are used to !enerate si!nals. e!
2sed as a local oscillator to transfor+ t$e R
si!nals to I si!nals in a recei,er
2sed to !enerate R carrier in a trans+itter
2sed to !enerate cloc5s in di!ital s(ste+s
2sed as s-ee* circuits in 7 sets and "RO
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Ref:061031 EE3110 Oscillator 4
Linear Oscillators
1 Wien rid!e Oscillators
) R" #$ase%&$ift Oscillators
3 L" Oscillators
4 &ta'ilit(
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Ref:061031 EE3110 Oscillator 8
Inte!rant of Linear Oscillators
or sinusoidal in*ut is connected
9Linear 'ecause t$e out*ut is a**ro;i+atel( sinusoidal
linear oscillator contains:
% a fre/uenc( selection feed'ac5 net-or5
% an a+*lifier to +aintain t$e loo* !ain at unity
+
+ +*lifier
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Ref:061031 EE3110 Oscillator 6
asic Linear Oscillator
+
+
&electi,eNet-or5
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Ref:061031 EE3110 Oscillator A
Wien rid!e Oscillatorre/uenc( &election Net-or5
Let 11
1
CX
C = and
111 CjXRZ =)
)
1
CXC =
))
))
1
))
)
11
C
C
C jXR
XjR
jXR
Z
=
+=
$erefore. t$e feed'ac5 factor.
=B
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Ref:061031 EE3110 Oscillator C
can 'e re-ritten as:
=< )1)1))1))1
))
CCCCC
C
XXRRjXRXRXR
XR
+++=
orBarkhausen Criterion. i+a!inar( *art > 0. ie.
0)1)1 = CC XXRR
&u**osin!.
R1>R)>R andX"1>X")>D".
)1)1
)1
)1
B1
11or
CCRRCC
RR
=
=
=
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Ref:061031 EE3110 Oscillator
E;a+*le
Rf
F
R
R
C
CZ1
Z)
R1
Vo
( settin! . -e !et
I+a!inar( *art > 0 and
RC
1=
3
1=
Gue toBarkhausen Criterion.
Loo* !ainA,>1-$ere
A, : ain of t$e a+*lifier
1131 R
R
AA f
vv +===
)1
=R
Rf$erefore. Wien rid!e Oscillator
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Ref:061031 EE3110 Oscillator 10
R" #$ase%&$ift Oscillator
F
Rf
R1
R R R
C C C
2sin! an in,ertin! a+*lifier
$e additional 1C0o*$ase s$ift is *ro,ided '( an R"
*$ase%s$ift net-or5
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Ref:061031 EE3110 Oscillator 11
**l(in! K7L to t$e *$ase%s$ift net-or5. -e $a,e
R R R
C C C
V1 Vo
I1 I) I3&ol,e forI3. -e !et
=)
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Ref:061031 EE3110 Oscillator 1)
$e out*ut ,olta!e.
=)
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Ref:061031 EE3110 Oscillator 13
L" Oscillators
F
~
A, Ro
Z1 Z)
Z3
12
Z*
$e fre/uenc( selectionnet-or5
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Ref:061031 EE3110 Oscillator 14
F
~A, Ro
Z1 Z)
Z3Z*
Vf Vo
3)1
31)
31)
=
