Diodes
A zener diode only works in (reverse/forward) bias
reverse
A zener diode is used to intentionally conduct ____ current. Also known as a _____ _____.
reverse voltage regulator
A zener diode resembles that of a conventional diode with a slight alteration to the cathode element. What is it?
A flag at each end of the cathode
Define diode
A unidirectional device that will allow current to flow in only one didection
A diode contains n and p materials separated by a junction called the
PN junction
***Breakdown voltage is typically between
-50 - 100V
What is the turn on voltage for germanium?
0.2 - 0.3VT
What is the turn on voltage for silicon?
0.6 - 0.7VT
4 diode uses and what they mean
1. Rectifiers : used to convert ac into dc 2. Switches : opens or closes a circuit under the proper conditions 3. Limiter: limit the amplitude of input signals at the output of the current 4. Clampers: used to add dc voltage level to an ac input signal
What is doping?
A process of adding impurities (in controlled amounts) to semiconductor material to increase its conductivity
In schematics, the Anode is represented by an _____ and is the ____ side of the diode
Arrowhead Positive
Voltage is also known as ____ and is directional
Bias
Electron flow is always from the ___ to the ___.
Cathode Anode
Diode Reference designator
D or CR
____ flow toward the positive charge
Electrons
______ are the minority carrier in P type material
Electrons
What are the 2 most commonly used semiconductor materials?
Germanium and silicone
____ are the majority carriers in P type material
Holes
____ are the minority carriers in N type marerisl
Holes
____ flow toward the negative charge
Holes
Semiconductors offer less resistance than —-, but more than —-.
Insulators Conductors
Three most common types of diodes
Junction Zener LED
Electrons are the majority carriers in ___ type material
N type
The cathode of a diode represents the ___ material and has an increase of ____ _____
N type Free electrons
The anode represents the ___ type material and has an increased number of ____.
P type Holes
In a reverse biased junction, negative potential is applied to the ____. Positive potential is applied to the ___.
P-material (anode) N-material (cathode)
In schematics, the cathode is represented by a _____ _____ and is the _____ side of the diode.
Single line Negative
T/F There are no mobile carriers in the depletion region
T
In a reverse biased junction, the source now (aids/inhibits) barrier potential. The junction has a very (high/low) resistance to current flow.
aids high
The purpose of a junction diode is to
allow current flow in one direction only
In forward bias, the positive potential is applied to the _____ and the negative potential is applied to the ____.
anode (p-material) cathode (n-material)
Forward bias must have a potential large enough to overcome ____ ____
barrier potential
____ is the application of a voltage across a PN junction that aids (forward bias) or opposes (negative bias) current flow
bias
Current flow is a function of ____. Increasing forward bias voltage increases _____.
bias current
___ occurs when there is excessive reverse bias voltage and causes the depletion region to break apart, which cause a very large flow of current.
breakdown (A diode will be damaged due to heat generated by the large amount of current)
An LED schematic symbol looks like a junction diode, except that it has two arrows pointing outward from the ____
cathode (bar)
When forward biased and above VT, the junction diode acts like a ___ ___ allowing current to flow freely
closed switch
A forward biased diode is said to be "___" when current flows through it.
conducting
Forward bias ___ the width of the depletion regions
decreases
The recombination area is called the ___ ___
depletion region
P material loses holes near the junction through recombination with ___
electrons
N material loses electrons near the junction through recombination with ____
holes
in reverse bias, the depletion region is (increased / decreased)
increased
Reverse biased is when bias voltage is ____ to reach VT or bias source polarities are reversed from forward bias
insufficient
A zener diode placed forward bias in a circuit operates like a ____ diode.
junction
When P and N material are initially joined together, electrons from N-material diffuse to ____ concentration across the junction into the P material and holes from the P material diffuse across the junction into the ___ _____
lower N material
If voltage applied to a circuit falls below breakdown voltage, the zener diode will revert to acting like an ___ ____.
open switch
When reversed biased or below VT the junction diode acts like an ____ ____, preventing current flow
open switch
An LED emits light when (+ / -) voltage passes through it.
positive
Forward bias offers (very little / a lot) of resistance to current flow
very little