ehb 231 chap 2 diode circuits
TRANSCRIPT
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 1Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 2 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
• Rectifier circuits
• Zener diode circuits
• Clipper and clamper circiuts
• Multiple diode circuits
Chapter 2 Diode Circuits
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 3Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
DC Power Supply
AC
220V (rms)
50 Hz-
+
V s
+
-
Voltage
Transformer
Diode
rectifier Filter
Voltage
Regulator Load
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 4Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Diode Model
V S
V 0
VD0
0
Slope=R/R+r D
V S
V 0
VD0
VS
VD0V
t
Input and output waveforms for r D
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 5 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Transfer characteristic assuminga constant junction voltage
Full-wave rectifier
+
V 0 -
D1
-
V s +
R+
ac
-D2
+
V s -
V 0
VD00
Slope=1
- VD0
Slope=-1
v Input and output waveforms
V S
V 0 VS
VD0
t
- V S
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 6 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Bridge (full-wave) rectifier
Input and output waveforms
V S
V 0 VS
2VD0
V
t
- V S
ac
-
+
V s
+
-D2
D4+ V 0 - D1
RL
D3
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8/15/2019 EHB 231 Chap 2 Diode Circuits
7/25Slide 7 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Voltage & Current WaveformsIn Peak Rectifier Ckt (CR >>T).
+- RV S
I D
C+V 0 -
I C
I R
V 0
Vr
T
V p
t t 2 t 1
t
Conduct ion
interval
t
t
I L
I D
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8/15/2019 EHB 231 Chap 2 Diode Circuits
8/25Slide 8 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
A 5-V Regulated Power Supply
D1
D2
1
0
3
5
6 7
4
2
14:1
14:1
V 0
+
-
R 100 M Isolation
R
500
load
R=160
C
583 F
5.1 V
R =0.5s
V
120V - rms
@ 60 Hz
ac
10 V
0 V
2 V
4 V
6 V
8 V
0 50 100 150 200
Smoothing-capacitor voltage
Loading voltage
v( 7,4 ) v( 6,4)
Time, ms
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8/15/2019 EHB 231 Chap 2 Diode Circuits
9/25Slide 9Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Voltage-Doubler Circuit & Waveforms
+
-
1 32 D2
D1
c120V
– 20V
V(2)
Time (ms) – 20V
0V
V(3)
10V
– 10V
V(1)
2
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8/15/2019 EHB 231 Chap 2 Diode Circuits
10/25Slide 10 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Limiting & Clamping Ckts: Example-1
+
V 1
-
R
+
V 0
-
1
1
0.7
V0
V1
Describe transfer characteristic of the circuit
For V i < V DO = 0,7V
Diode is O.C.
V 0 =V i
+
0,7V
+V i-
+V 0-
V 0 =V i for V i
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8/15/2019 EHB 231 Chap 2 Diode Circuits
11/25Slide 11Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Limiting & Clamping Ckts: Example-2
1
1
-0.7
V0
V1
+
V 1
-
R
+
V 0
-
Describe the transfer characteristic
For V i > -V T = -0,7V
Diode is O.C.
V 0 =V i
0,7V
+
+V i-
+V 0-
Transfer characteristics
V 0 =V i for V i > -0,7V= -V DO V 0 =0,7 V for V i -0,7V
+V i
-
+V 0-
For V i -V DO = -0,7V
Diode is S.C.
V 0 =-V DO =-0,7V
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8/15/2019 EHB 231 Chap 2 Diode Circuits
12/25Slide 12 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Limiting & Clamping Ckts: Example-3
+
V 1
-
D1
D2
R
+
V 0
-
+0.7
-0.7
V0
V1
For
-V DO =-0.7
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8/15/2019 EHB 231 Chap 2 Diode Circuits
13/25Slide 13Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Limiting & Clamping Ckts: Example-4
5 V
R
+
V 1
-
+
V 0
-
1
1
5.7
+5.7
V0
V1
Describe the transfer characteristics of the circuit
V V for V < 5v+ 0.7v
V = 5v+ 0.7v for V 5v+ 0.7v
o i i
o i
io
DOi
VV
O.C.isDiode
5.7V5vVFor
5.7vV5vV
S.C.isDiode
, 5.7vV5vV
For
DOo
DOi
5 V
R
+
V i
-
+
V 0
-
0.7 V+
+
+
V i
- 5 V
R
+
V 0
-
+
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8/15/2019 EHB 231 Chap 2 Diode Circuits
14/25Slide 14Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Limiting & Clamping Ckts: Example-5
)()( 21 DOi DO vvvvv z z
DZ1 and DZ2 are OC ivv 0
R
+
v i
-
1Z
2 Z
+
v 0
-
Descr ibe th e transfer character is t ic of th e circuit
v 0
1
1
DO Z V V
1
DO Z V V
2
v i
v). z ( vvi 702 ). z ( z vvvv D O 70210
v). z ( vvi 702 70
220 . z z vvvv
DO
DZ1 is SC and DZ2 is OC
DZ1 is OC and DZ2 is SC
i 0 v v = for )0.7v z ( 0.7v) z ( 2 i 1 v v v
0.7v) z ( 10 v v for 0.7v) z ( 2 i v v
0.7v) z ( 10 v v 0.7v) z ( 2 i v v for
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8/15/2019 EHB 231 Chap 2 Diode Circuits
15/25Slide 15 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Additional Examples
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8/15/2019 EHB 231 Chap 2 Diode Circuits
16/25Slide 16 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
+ v D (t) –
i D (t)
If v D 0 & i D >0
OC
SC
v D
i D
0OC
SC
Ideal Diode Model
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8/15/2019 EHB 231 Chap 2 Diode Circuits
17/25Slide 17 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
I R(t)=?
Example 1 :
0.5cos(t) V1
~
1 V
+vR(t)
–
I.D.
Limiting & Clamping Ckts: Ex. 1
V
0
0,51
I S 1+0.5cos(t)(t)=
0.5cos(t)t
1,5
л/2 л 3л/2 2л
1V
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8/15/2019 EHB 231 Chap 2 Diode Circuits
18/25Slide 18 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
Assume that diode is OC
i d (t)=0 for all t
V d (t) = 1+0.5cos(t)
V d (t) > 0
Assumption is not correct !
+ v d
(t) –
id(t)
0.5cos(t) V 1~
1 V
Ω
i d (t) = V s (t) / RV s (t) = i d (t) . R
= V R (t)
i d > 0 for all t
diode is SC for all t
Assumption is correct!
Assume that diode is SC
i d (t)
0.5cos(t) V 1~
1 V
Ω
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8/15/2019 EHB 231 Chap 2 Diode Circuits
19/25Slide 19Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
i d (t) = ?
+v s (t)
–
~
+ v R (t) –
R = 1
+v d (t)
–
ID
v s (t) = 0.5 + sin(t) (V)
v s (t )
π/2
t
-1.0
0.5
1.5
0.5
0.0
1.0
D: ON
π 3π/2 2π
v s (t ) = 0.5 + sin (t )
Limiting & Clamping Ckts: Ex. 2
D: OFF D: ON D: OFF
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8/15/2019 EHB 231 Chap 2 Diode Circuits
20/25Slide 20 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
+v s (t)
–
+ v R (t) –
~ +v d (t)
–
i d (t) For Vs(t) > 0
Assume that: DIODE SC
V d (t) = 0
i d (t) = V s (t) / R
= 0.5+sin(t) A
i d (t) > 0
Assumption is correct!V R (t) = i d (t) . R = V s (t)
1 Ω
~
+ v R (t) –
1
+v d (t) –
For V s (t)
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8/15/2019 EHB 231 Chap 2 Diode Circuits
22/25Slide 22 Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
R
+
v 0 (t )
-
~v i (t)
V a
ID
R
Plot v 0(t) & v 0(t) vs v i(t) .
+v d (t)
-
i d (t)
Diode: SC v d (t) = 0, i d (t) > 0
i d (t) = (v i (t) - Va ) / R
v i (t) > Va
v 0 (t) = V a
Diode: OC v d (t) < 0, i d (t) = 0
- v i (t) + i d (t).R + V a + v d (t) =0
v d (t) = v i (t) - V a < 0
v i (t) < V a
v 0 (t) = v i (t)
~ v i (t)
+
v 0 (t)
-
R
~ v i (t)
V a
i d (t)
i d (t)
Limiting & Clamping Ckts: Ex. 3
+
v 0 (t)
-
V a
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8/15/2019 EHB 231 Chap 2 Diode Circuits
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Slide 23Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
va
0
v 0 (t)
v i (t) va
( v 0 (t) vs v i (t) )
v(t)
va
0
t
v i (t)
v 0 (t)
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Slide 24Mustafa Karaman EHB 231 Elektronik - I Chapter 2: Diode Circuits
v i (t)
+
v 0 (t)
-
~
V a
R s
R 0
ID+
v d (t) -
i d
Plot v 0 (t), v 0 (t) vs vi (t) .
Diode: SC
+
v 0 (t)
~
v a
R s
R 0
+
v d (t)
-
i d (t) v i (t)
Limiting & Clamping Ckts: Ex. 4
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+
v 0 (t)
-
~
v a
R s
R 0
+
v d (t)
-
i d (t)
v i (t)
diode: OC
v d (t) < 0, i d (t) = 0 v i (t)+ R s . i d (t) + v d (t)
+ R 0 . i d (t) + v a =0
v d (t) = v i (t) - v a < 0
v i (t) < v a
v 0 (t) = v i (t)
va
v(t)
0 t
v i (t)
v 0 (t)
R0/(R0+ Rs)
va
0
v0(t)
vi(t)va
va. RsR0+ Rs