أسس الهندسة الإلكترونية

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‫إلكترونية‬ ‫هندسة‬ ‫أسس‬-‫ثالثة‬ ‫سنة‬-‫القادري‬ ‫منذر‬ ‫محمد‬ ‫المهندس‬ ‫الدكتور‬ munthear@gmail.com
1
Basic Electronic Circuit Concepts
circuits
Fundamentals

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‫إلكترونية‬ ‫هندسة‬ ‫أسس‬-‫ثالثة‬ ‫سنة‬-‫الدكتور‬
‫القادري‬ ‫منذر‬ ‫محمد‬ ‫المهندس‬
munthear@gmail.com 2
Evolution of Electronics ‫اإللكترونيات‬ ‫تطور‬
1941-1956
Vacuum Tube
1948
Transistor
1964-1971
Integrated circuit
1971
Microchip (VLSI)
1980
ULSI
1995
Nano Electronic

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‫إلكترونية‬ ‫هندسة‬ ‫أسس‬-‫ثالثة‬ ‫سنة‬-
‫القادري‬ ‫منذر‬ ‫محمد‬ ‫المهندس‬ ‫الدكتور‬
‫الترانزستورالبكر‬ ‫المفرغ‬ ‫الصمام‬

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Semiconductor Devices

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‫اإللكترونية‬ ‫الهندسة‬ ‫أسس‬ ‫منهاج‬ ‫مفردات‬
Semiconductor Devices
Diodes
Transistors
 BJT
 FET (MOFET, JFET)
 UJT
Thyristors( SCR,SCS,PUT)
Triac,Diac
Optoelectronics

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SEMICONDUCTOR DEVICES
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THE PROCESSOR
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Direction of Current Flow

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‫النواقل‬ ‫أنصاف‬ ‫فيزيائية‬
•‫موجبة‬ ‫شحنات‬ ‫ذات‬ ‫ونواة‬ ‫سالبة‬ ‫شحنات‬ ‫ذات‬ ‫الكترونات‬ ‫من‬ ‫الذرة‬ ‫تتألف‬
•‫اإللكترون‬ ‫شحنة‬=1,6 exp –19 C
•‫أكبر‬ ‫البروتون‬ ‫كتلة‬2000‫اإللكترون‬ ‫من‬ ‫مرة‬
•‫البروتون‬ ‫كتلة‬=‫النيترون‬ ‫كتلة‬.
•‫خاصة‬ ‫طاقة‬ ‫بمستويات‬ ‫النواة‬ ‫حول‬ ‫اإللكترونات‬ ‫تدور‬.‫ذات‬ ‫األقرب‬ ‫والمدارات‬
‫أقل‬ ‫طاقة‬ ‫سويات‬.
•ev=‫فولتا‬ ‫يساوي‬ ‫كمون‬ ‫فرق‬ ‫عبر‬ ‫إلكترون‬ ‫لتحريك‬ ‫الالزمة‬ ‫الطاقة‬ ‫كمية‬‫واحدا‬
•‫الطاقة‬ ‫ثغرة‬energy gaps‫إلكترون‬ ‫أية‬ ‫بها‬ ‫يوجد‬ ‫ال‬.
•‫التكافؤ‬ ‫حزمة‬Valence band‫مهيجة‬ ‫غير‬ ‫لذرة‬ ‫األبعد‬ ‫الطاقة‬ ‫حزمة‬ ‫هي‬
•‫نسبيا‬ ‫حرة‬ ‫اإللكترونات‬ ‫فيها‬ ‫تكون‬ ‫الناقلية‬ ‫حزمة‬.

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Resistance
Charges passing through any conducting medium collide with
the material at an extremely high rate and, thus, experience
friction.
The rate at which energy is lost depends on the wire thickness
(area), length and physical parameters like density and
temperature as reflected through the resistivity
R
l
A




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‫الطاقة‬ ‫حزم‬ ‫مخطط‬
‫الناقلية‬ ‫حزمة‬
‫التكافؤ‬ ‫حزمة‬
‫الطاقة‬ ‫فجوة‬}
‫إزدياد‬
‫الطاقة‬

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‫والعوازل‬ ‫النواقل‬ ‫في‬ ‫التكافؤ‬ ‫حزم‬
•‫أخرى‬ ‫إلى‬ ‫مادة‬ ‫من‬ ‫الطاقة‬ ‫حزم‬ ‫تختلف‬.
•‫إلكت‬ ‫التستطيع‬ ‫حيث‬ ‫عريضة‬ ‫الطاقة‬ ‫ثغرة‬ ‫تكون‬ ‫العازلة‬ ‫المواد‬ ‫في‬‫رونات‬
‫بسهولة‬ ‫الناقلية‬ ‫حزمة‬ ‫إلى‬ ‫اإلنتقال‬ ‫التكافؤ‬.
•‫الطاقة‬ ‫ثغرة‬ ‫تنعدم‬ ‫الناقلة‬ ‫المواد‬ ‫في‬
EG=6ev EG=1ev
‫التكافؤ‬ ‫حزمة‬ ‫التكافؤ‬ ‫حزمة‬
‫التكافؤ‬ ‫حزمة‬
‫الناقلية‬ ‫حزمة‬ ‫الناقلية‬ ‫حزمة‬
‫الناقلية‬ ‫حزمة‬

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Intrinsic Semiconductor
‫على‬ ‫السيلكون‬ ‫ذرة‬ ‫تحتوي‬14‫التكافؤ‬ ‫رباعي‬ ‫عنصر‬ ‫وهو‬ ‫إلكترون‬
‫على‬ ‫الجرمانيوم‬ ‫ذرة‬ ‫تحتوي‬32‫التكافؤ‬ ‫رباعي‬ ‫عنصر‬ ‫وهو‬ ‫إلكترون‬

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Intrinsic Semiconductor
. ‫حر‬ ‫إلكترون‬
‫ثقب‬
-‫الذرية‬ ‫الروابط‬ ‫تنكسر‬ ‫للحرارة‬ ‫الناقل‬ ‫نصف‬ ‫بتعرض‬
-‫شحنة‬ ‫كحامل‬ ‫يخدم‬ ‫الثقب‬

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‫النواقل‬ ‫وأنصاف‬ ‫النواقل‬ ‫في‬ ‫التيار‬‫النقية‬

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Drift ‫الجرف‬
Applying an electric field across a
semiconductor material, results in both
types of carrier moving in opposite
directions thus creating current flow.

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P-Type Semiconductor
N-Type Semiconductor
‫المعطية‬ ‫الشوائب‬:‫الفوسفور‬,‫األنتموان‬,‫ال‬‫زرنيخ‬
‫المستقبلة‬ ‫الشوائب‬:‫الجاليوم‬,‫األنديوم‬,‫البورون‬

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‫الفراغية‬ ‫البلورية‬ ‫البنية‬

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N-Type Semiconductor
‫تشكل‬
‫اإللكترونات‬‫األعظمية‬ ‫الحوامل‬
‫والثقوب‬‫األقلية‬ ‫الحوامل‬
‫بالزرني‬ ‫السليكون‬ ‫إشابة‬‫خ‬
‫نوع‬ ‫ناقل‬ ‫نصف‬ ‫يعطي‬N

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P-Type Semiconductor
‫تشكل‬
‫الثقوب‬‫األعظمية‬ ‫الحوامل‬
‫اإللكترونات‬ ‫و‬‫األقلية‬ ‫الحوامل‬
‫بالجالي‬ ‫السليكون‬ ‫إشابة‬‫و‬‫م‬
‫نوع‬ ‫ناقل‬ ‫نصف‬ ‫يعطي‬P

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Semiconductors
Extrinsic semiconductors can be doped with
both types of impurities, and their respective
concentrations determine the type material
they will become:
 N-type when ND > NA
 Majority carriers are free electrons and minority
carriers are holes.
 P-type when ND < NA
 Majority carriers are holes and minority carriers
are free electrons.

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Drift ‫الجرف‬
The magnitude of the electric field in volts/cm is
given by:
And the effective velocity of the carrier moving by the
drift action of an applied electric filed is given by:
Where n = 1350 cm2/V-s and p = 480 cm2/V-s are
the electron and hole mobility constants respectively.
L
V
E
Ennv  Eppv 

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P-N Junction
Created by bringing together a p-type
and n-type region within the same
semiconductor lattice.

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The Diode
n
p
p
n
B A
SiO2
Al
A
B
Al
A
B
Cross-section of pn-junction in an IC process
One-dimensional
representation diode symbol

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At the junction, free
electrons from the N-type
material fill holes from the
P-type material. This
creates an insulating layer
in the middle of the diode
called the depletion zone.
‫الوصلة‬ ‫نظرية‬P-N

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E

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‫المحرمة‬ ‫المنطقة‬ ‫عرض‬
- ---
- ----
- ----
- -----
+ + + +
+ + + +
+ + + +
+ + + +
- -
- -
- -
- -
+ +
+ +
+ +
+ +
‫اإلشابة‬ ‫مستوى‬ ‫على‬ ‫يعتمد‬ ‫المحرمة‬ ‫المنطقة‬ ‫عرض‬ ‫إن‬
P PN N
1 micron
Depletion

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Depletion Region ‫الناضبة‬ ‫المنطقة‬
hole diffusion
electron diffusion
p n
hole drift
electron drift
Charge
Density
Distance
x+
-
Electrical
xField
x
Potential
V


W2-W1

(a) Current flow.
(b) Charge density.
(c) Electric field.
(d) Electrostatic
potential.

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E
E

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Conductivity ‫أنصاف‬ ‫في‬ ‫الناقلية‬
‫النواقل‬
Property of a material.
It is a measure of the material’s ability
to to carry electric current.
It is given in Semiconductor by:
Measured in S-cm.
 pn pnq  

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Why Semiconductors?

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Forward Bias ‫األمامي‬ ‫اإلنحياز‬
x
pn0
np0
-W1 W2
0
pn(W2)
n-regionp-region
Lp
diffusion

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Reverse Bias ‫العكسي‬ ‫اإلنحياز‬
x
pn0
np0
-W1 W20
n-regionp-region
diffusion

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Potential Barrier ‫الكموني‬ ‫الحاجز‬
The charge barrier creates a state of balance
with the diffusion process, and this barrier
can be represented as a voltage or potential
barrier.

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Resistivity ‫المقاومية‬
Measured in -cm it is the reciprocal of conductivity:
The resistance of a material with constant cross section
can be calculated by:


1

A
L
R 
 ne ‫المعادن‬ ‫في‬ ‫الناقلية‬
 ‫االلكترونات‬ ‫حركية‬n ‫الحرة‬ ‫االلكترونات‬ ‫تركيز‬ e ‫االلكترون‬ ‫شحنة‬

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‫التيار‬ ‫كثافة‬Current
Density
Current per unit cross-sectional area.
Measured in A/cm2.
Given by:
 n ‫الحرة‬ ‫اإللكترونات‬ ‫تركيز‬ , p ‫الثقوب‬ ‫تركيز‬
 ‫الثقوب‬ ‫تركيز‬
* The direction of current flow vector is the
same direction as the electric field vector.
qEp p )(nEJ n  


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Diffusion ‫اإلنتشار‬
Diffusion current occurs because of the
physical principle that over time particles
undergoing random motion will show a
movement from a region of high
concentration to a region of lower
concentration.

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Diffusion
Current density is directly proportional to the
gradient of carrier concentration.
Dn and Dp are the diffusion constants for
electrons and holes respectively.





dx
dn
qDJ nn 




dx
dp
qDJ pp

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Diffusion Capacitance

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Diodes ‫الناقل‬ ‫نصف‬ ‫الوصلة‬ ‫ثنائي‬
A diode can be considered to be an
electrical one-way valve.
They are made from a large variety of
materials including silicon, germanium,
gallium arsenide, silicon carbide …
ANODE
D1
DIODE
CATHODE

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‫المثالي‬ ‫الناقل‬ ‫نصف‬ ‫الثنائي‬

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Diode Current

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Diode V-I Characteristic
For ideal diode, current flows only one way
Real diode is close to ideal
Ideal Diode

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Piecewise Linear Model
The real diode can
be approximated by
a model which uses
two connected line
segments.
Note that the turn
on voltage, VF ,
marks the point
where the two line
segments meet.

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The Diode Equation
The diode equation can be derived based on the
assumption that carriers move by diffusion.
 ID – Current through diode.
 IO – Reverse saturation current.
 VD – Voltage across the diode.
 k – Boltzmann’s Constant.
 n – Ideality factor (n = 1 for silicon).
 T – Temperature in degrees Kelvin.








 1nkT
qV
OD
D
eII 39
kT
q

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Dp/µp=DN /µN=VT ‫الحرارة‬ ‫لدرجة‬ ‫المكافئ‬ ‫الفولت‬(‫انشتاين‬ ‫عالقة‬)
VT=KT/e=T/11600 at 300K

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‫للثنائي‬ ‫الحرارية‬ ‫الخواص‬
V(T1)-V(T0)=KT(T1-T0)
KT=-2.5mv/c Ge
KT==2.0mv/c Si
I0(T2)=I0(T1)exp[Ki(T2-T1)]
Ki=0.07/C

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‫الناقل‬ ‫نصف‬ ‫الثنائي‬ ‫مقاومة‬








 1nkT
qV
OD
D
eII
T
o
T
v
v
o
V
II
V
eI
dv
dI
g
T




‫الديناميكية‬ ‫الناقلية‬
‫الديناميك‬ ‫المقاومة‬ ‫تكون‬ ‫وبالتالي‬ ‫جدا‬ ‫صغيرة‬ ‫الناقلية‬ ‫تكون‬ ‫العكسي‬ ‫اإلنحياز‬ ‫حالة‬ ‫في‬‫جدا‬ ‫كبيرة‬ ‫ية‬
‫يكون‬ ‫األمامي‬ ‫اإلنحياز‬ ‫حالة‬ ‫في‬Io<<I‫يكون‬ ‫وبالتالي‬:
I
V
g
r T

1
I
mv
I
V
r T 26


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The Diode Model
0.7V
Rr
Rf
Rr
Cf
CD
Cf
rd
‫الم‬ ‫للتيار‬ ‫المكافئة‬ ‫الدارة‬‫ستمر‬
‫األم‬ ‫اإلنحياز‬ ‫في‬ ‫المتناوب‬ ‫للتيار‬ ‫المكافئة‬ ‫الدارة‬‫امي‬
‫اإلنحياز‬ ‫في‬ ‫المتناوب‬ ‫للتيار‬ ‫المكافئة‬ ‫الدارة‬‫العكسي‬

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‫الحمل‬ ‫خط‬ ‫مفهوم‬Load Line
Vo
Io
Vs
r
R
Io
Vs Vo
Io
Vo=R . Io
Vo=Vs - IoRs
o
Q point

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‫الديناميكي‬ ‫الحمل‬ ‫خط‬AC- Load Line
Vs+vs
R1 R2
C
iD
vD
-1/Rdc
-1/Rac
Q

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Graphical Solution
Simplify the circuit
connected to the diode
to a Thevenin’s
equivalent circuit.
Analyze two cases:
 iD = 0;
 vD = 0.
This two points
identifies the
Thevenin’s circuit load
line, and this lines
intersects the diode plot
at the operating point.
‫البياني‬ ‫الحل‬

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‫مثالي‬ ‫لثنائي‬ ‫التقويم‬ ‫مبدأ‬

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‫المتناوب‬ ‫التيار‬ ‫تقويم‬ ‫مبدأ‬
‫الدو‬ ‫التابع‬ ‫متوسط‬ ‫هو‬ ‫الناتج‬ ‫المستمر‬ ‫الجهد‬‫ري‬

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‫المقومة‬ ‫الموجة‬ ‫تنعيم‬
Vs=V

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Full-wave Rectification
The output of a full-
wave rectifier is
driven by both the
positive and
negative cycles of
the sinusoidal input,
unlike the half-wave
rectifier which uses
only one cycle.

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Diode Bridge

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‫التعرج‬ ‫حسابات‬Ripple
Full-wave ripple frequency is twice AC frequency
Ripple Factor=Vr(rms)/Vdc

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Filtering
The reduction in
voltage between
charging cycles is
dependent on the
time constant stated
below:
  

t
m
L
eVtv
CR




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Ripple Factor
Ripple is the small voltage variation
from the filter’s output.
Good power supplies produce as little
ripple as possible.
Ripple is usually specified as Ripple
Factor, RF :
valuedc
rippleofvaluerms
RF 

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Voltage Doubler

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Voltage Doubler
Voltage doublers allow you to develop higher
voltages without a transformer.
Stages can be cascaded to produce triplers,
quadruplers, etc.
Voltage multipliers usually supply low currents to a
high-resistance load.
Output voltage usually drops quickly as load current
increases.

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‫الموجات‬ ‫تشكيل‬

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Diode Types
Rectifier Diode
Fast Recovery Diode
Zener Diode
Current Regulator Diode
Schottky Diode
Varactor Diodes
Tunnel Diode
PIN Diode
Photodiode
Light Emitting Diode (LED)
Laser Diode

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Diode Applications
Rectifying
Reverse Voltage Protection
Over voltage protection
Switching
Signal shaping
Variable Capacitor
Variable Resistor
Oscillator
Display
Light Sensing
Temperature Sensing

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Zener Diode

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Diodes - Simple Applications
Why would you want the equivalent of an electronic check-
valve?

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Diode Current-Voltage relationship
The characteristics of all silicon based
diodes are effectively the same,
showing a sharp exponential increase
in current at forward bias and only a
few As at reverse bias.
Note that this “knee” is temperature-
dependent as observed in lab 1.
The non-ideal behavior shows a slower
than exponential increase due to a
series resistance, like the inductor.
At large reverse-bias (not shown)
current starts to flow. We will discuss
this region later.
1N4148 characteristics

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Diode models
A diode is often approximated as a
2-terminal device with ~0.7 v
drop as long as 1-100 mA are
flowing in the forward direction.
The curves for a typical switching
signal diode show why this is OK
(note the log scale for current).
When it is either reverse or
weakly forward biased it is
modeled as an open circuit.
Real diodes and the symbol
are shown. The arrow points
in the direction of forward
current flow.

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More Diode Physics
Pure semiconducting materials like Silicon have very high resistivity at room
temperature. However it can be made conductive by adding extra electrons. In
n-type material this is done via atoms with one more electron than silicon
(phosphorus). It can also be more conductive if one electron is removed,
allowing the resulting “holes” to move about (they are really absences of
valence or bonding electrons that hop from one site to the next). This is done in
p-type material by adding elements with one less electron (aluminum). This is
known as doping.
An interesting thing happens if p- and n-type material are in contact. A region
that has no holes on the p-side and no electrons on the n-side forms, called the
depletion region. This area is like the original pure semiconductor and does not
conduct, making the junction a very poor conductor again. However if it is
biased (meaning a voltage is applied) with the p-type positive relative to the n-
type, the depletion region shrinks.
This is the origin of the one-way flow. The next slides describe why this is,
using images from the website http://jas.eng.buffalo.edu/

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When material with lots of electrons (n-type) is brought into
contact with material with lots of holes (p-type) the electrons and
holes diffuse, resulting in a large current. However the loss of
these carriers leaves a depleted region that is charged (because of
the P and Al ions left behind) and reduces the current since the
electric field repels the carriers.
Diode Current-Voltage relationship (1)

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At zero bias electrons
(holes) flow left (right)
because of diffusion and
an equal amount flow right
(left) due to the electric
field, resulting in no
current. As the depletion
region increases with
reverse bias (not shown),
the diffusion current to the
left decreases leaving only
a small reverse saturation
current due to the field.
Notice that for these doping levels the
depletion region is 0.15 microns thick.

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At positive bias the depletion
region is reduced and many
electrons (holes) diffuse left
(right) while only a small amount
flow right (left) due to the
electric field, resulting in a large
current (sum of holes and
electrons) flowing right.
When an electron gets to the p-
type material it recombines with
a hole. If it does this in the
depleted region the ideality
factor N is 2, while it is 1 if
recombination occurs outside.
The depletion region is now only 0.05
microns thick.

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Types of diodes
Power diodes (or rectifiers) - designed to handle large currents,
typically used on power supplies or for switches. Typical values
(for 1N4002)
Max Average current: 1 A Peak current: 30 A
Reverse voltage: 100 v
Signal diodes - low powered, often faster switching (smaller
depletion region). Typical values (for 1N4148)
Max Average current: 100 mA Peak current: 450 mA
Reverse voltage: 75 v Recovery time: 4 ns
Zener diodes - voltage regulation, similar to power diodes but
has any important specification: the zener voltage, Vz (more later).
Designed to breakdown at precise voltage (range 1-400 v).

2/19/2012
Clamp (or clipper)
Vin
R
Vout
What does this circuit do? As
mentioned in the text it
“clamps” or “clips” the output
voltage. If the magnitude of
the input exceeds Vbatt+0.7 v,
either negative or positive, the
diode starts conducting. This
limits the maximum voltage
(this is similar to surge
protectors).
Vbat
One limitation of this is that by design it will distort a time-
varying voltage input, cutting it off at a max and a min
value.

2/19/2012
Stiff Clamp
Vin
C
Vout
This circuit on the other hand works
very well at higher frequencies in
limiting the minimum voltage on
the output. Treating the diode like a
simple one-way switch we see that
the output can never fall below -0.7
v, because then the diode begins
conducting.
How does the circuit do this? If the input voltage is less than this
minimum, current flows counterclockwise, charging the left
capacitor plate negative and the right plate positive. This capacitor
voltage adds to the input, raising it to a minimum of -0.7 v, when
current stops flowing. Note that it is the opposite if the diode is
reversed because the currents flow clockwise.

2/19/2012
Zener diode - IV characteristics
All diodes show a breakdown under
reverse bias when the internal electric
field gets very high, ripping electrons
from atoms. This avalanche breakdown
occurs typically at -50 to -1000 v.
If the depleted region that acts like a
barrier to current is thin there is another
possibility. The electrons can quantum
mechanically tunnel from the n- to the p-
side, resulting in a reverse current. This
can be engineered to occur at a precise
voltage called the Zener voltage, VZ.
V
I
VZ
IIIIII
The graph shows three distinct regions, as labeled. Region III is
where zener diodes normally operate.

2/19/2012
Zener diode - voltage regulator (1)
How can a zener regulator act to control the
output voltage? In the circuit shown (note
that the zener is connected so that it is
reverse biased) current flows through the
zener and it is in region III, so the voltage
drop across it is VZ.
A zener only works as a regulator because
it ensures that enough current is drawn
through the series resistor so that the
voltage drop results in Vout=VZ.
If no current flows through the zener
(actually less than a few mAs) it no longer
regulates because it is in region II.
Vout
UnregulatedVin

2/19/2012
Zener diode - voltage regulator (2)
Rload
UnregulatedVin
Rload
UnregulatedVin
The voltage across the load is
VZ since there is current
through the zener (Region III)
RR
The voltage on the load is
Rload/(R+Rload)Vin because
there is no current through the
zener.

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