Post on 17-Jan-2016
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Chapter 4Common Diode ApplicationsClippers, Clampers, Voltage Multipliers, Displays, and
Logic Circuits
By jashvir chhikara
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Objectives
• State the purposes served by clippers, clampers, and voltage multipliers.
• Describe the operation of series and shunt clippers.
• Describe the effects of negative and positive clampers on an input waveform.
• Describe the use of the LED in multisegment displays.
• Study simple diode logic circuits.
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Fig 4.1-11 Clipper (limiter) circuits. (1)
Negative series clipper.
D1
RL
Vin Vin-0.7V
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Fig 4.1-11 Clipper circuits. (2)
Positive series clipper.
D1
RL-Vin
-Vin+0.7V
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Fig 4.1-11 Clipper circuits. (3)
Negative shunt clipper.
RS
D1 RL
IT
Vin(pk)in(pk)
L
L S
RV
R R
-0.7V
RS
D1 RL
IF
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Fig 4.1-11 Clipper circuits. (4)
Positive shunt clipper.
+0.7V
RS
D1RLIF
in(pk)L
L S
RV
R R
RS
D1 RL
IT
-Vin(pk)
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Fig 4.1-11 Clipper circuits. (5)
Biased shunt clipper.
VB
RS
RLVB + 0.7V
VB
RS
RL -VB - 0.7V
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Fig 4.1-11 Clipper circuits. (6)
Adjustable shunt clipper.
+VB
RS
RL
Vin
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Fig 4.12-13 Clipper applications. (1)
Transient-protection circuits
A
+5 V
D1
D2
Transient
+5 V
0 V
-5 V
On
ILReverse
Off
IL
ForwardFree-wheeling diode
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Fig 4.12-13 Clipper applications. (2)
AM detector
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Fig 4.14 Clampers (DC restorers).
Input signalsource
Positiveclamper
Load
0V 0V20Vpp
20Vpp
Input signalsource
Negativeclamper
Load
0V20Vpp 0V20Vpp
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Fig 4.15 Clamper operation. (1)
C1
D1 RL
+VS
TC = 5(RD1C1)
C1
D1 RL
-VS
TD = 5(RLC1)
Charge Discharge
TC << TD
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Example 4.5
Determine the capacitor charge and discharge times for the circuit represented in Fig. 4.15. Assume that the forward resistance of the diode (RD1) is 10 , RL = 10k, and C1 = 1F.
1 1
1
5 5 10Ω 1μF 50μs
5 5 10kΩ 1μF 50ms
C D
D L
T R C
T R C
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Fig 4.16 Clamper operation. (2)
D1 RL5 V
On
VC
VC5 V
D1 RL5 V
Off
+5 V
-5 V
0 V
-10 V
0 V
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Fig 4.17 Clamper circuits.
C1
D1 RL
C1
D1 RL
Negative clamper Positive clamper
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Fig 4.18-19 Biased clampers.
Biased clampers.
VZ
C1
D1 RL
C1
RLVZ
D1
VB
C1
D1
R1
RL-VB
C1
D1
R1
RL
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Fig 4.20 Voltage multipliers. (1)
Half-wave voltage doublers.
VS
C1
D1
D2
C2 RL
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Fig 4.21 Voltage multipliers. (2)
Operation of half-wave voltage doublers.
VS(pk)
C1 D1
D2
C2 RLOn
Off
IS IL
VS(pk)
VC2
VS(pk)
C1 D1
D2
C2 RLIS
Off
OnVS(pk)
VC2
VC2=2VS(pk)
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Fig 4.23 Full-wave voltage doubler.
VS
D1
D2
C1
C2
VS(pk)
VS(pk)
C3 2VS(pk) RL
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Cockcroft-Walton Circuit
vi
2vp
vp
2vp
2vp 2vp
5vp
4vp
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Fig 4.28-29 Multisegment displays.
a
g
d
b
c
dp
f
e
Common cathode
COM
a
b
c
d
COM
dp
g
f
e
7-segment display
16-segment alphanumeric
display
5x7 dot matrix display
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Diode Logic Circuits (1)
V1
V2
Vo
5V
R5k
V1 V2 Vo
0V 0V 0.7V
0V 5V 0.7V
5V 0V 0.7V
5V 5V 5V
AND function
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Diode Logic Circuits (2)
V1 V2 Vo
0V 0V 0V
0V 5V 4.3V
5V 0V 4.3V
5V 5V 4.3V
OR function
V1
V2
Vo
R10k
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Summary
• Clippers (limiters).• Clipper applications.• Clampers (dc restorers).• Voltage multipliers.• LED applications.• Diode logic circuits.