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### Transcript of Basic Electronics - George Mason rubinp/courses/407/ Electronics Review Linear (Ohmic) Components...

• Basic Electronics Review Linear (Ohmic) Components Non-Linear Components Amplifiers and Pulse Electronics Power Supplies Digital Electronics Grounds and Grounding

• Review I I [A] = Q [C] / t [s] A Cs-1

To measure current through a component, connect an ammeter in series with it

EMF [V] = E [J] / Q [C] V JC-1 To measure potential difference across a component,

connect a voltmeter in parallel with it

P [W] = E [J] / t [s] = IV W Js-1

• Review II Ohm's Law: V = IR Kirchhoff's Rules

Loop Rule: (voltage drops around a closed loop) = (voltage sources)

Node Rule: (current into a node) = (current out of a node)

• Review III

Resistance R []: a measure of current flow restriction Ohmic conductors (resistors) obey Ohm's Law Sums in series; inverse sums in parallel

• Review IV Capacitance [C]: ability to store energy in an

electric field Determined by surface area (directly), surface

separation (inversely), and dialectric (insulator) between surfaces

Inverse sums in series; sums in parallel

• Review V Inductance [L]: ability to store energy in a

magnetic field Determined by number of turns (directly),

permeability of core (directly), cross sectional area of core (directly), spacing of turns (inversely)

Sums in series; inverse sums in parallel

• Review VI AC Circuitry Voltage changes with time

Impedance (frequency dependent)

Combine like resistance

• Component Selection CriteriaChoosing the right type for the intended function Nominal value and tolerance Stability: Temperature, etc. / Environment Interactions: Heating and out-gassing Shape / Size Power dissipation and voltage rating Frequency characteristics Derating Cost

• Linear (Ohmic) Components Resistors

Fixed Variable

Capacitors Transmission Lines Coaxial Connectors Relays

• Resistors I Fixed

Types

Precision Film

• Typical Fixed Resistors

Type Carbon Film Metal Film WirewoundSurface Mount

Tolerance 2-10% 0.1-5% 0.1-5% 0.1-5%

Power Rating 0.125-2W 0.1-5W 1-200W

0.0125-0.25W

Temp Coefficient

250-450 ppm/K

10-350 ppm/K

20-400 ppm/K

25-200 ppm/K

• Resistors II Variable

• Resistors III Voltage divider

• Voltage Divider Generalized

• Capacitors I Voltage Rating: Measured as DC (AC of same

value has peak voltages too high) Polarized: must always have DC voltage, of

the correct polarity, exceeding any AC voltage

• Capacitors II Voltage divider

• Inductors I

• Inductors II Voltage divider

• Transmission Lines I Voltage and current propagated as waves;

guide TEM waves

• Transmission Lines II Terminate R = Z0

Single Wire Twisted Pair CoaxialCable

Microstrip Strip Line(Triplate)

Characteristic Impedances, Z0

• Coaxial Connectors Smaller cables have greater attenuation Many types

Coupling Method Cable Size Maximum Frequency RMS Working Voltage

• Relays

Electrically actuated (electromechanical or solid-state) switches Operating voltage Power rating Contact current rating Speed Noise Contact conditioning

• Non-Linear Components Band Theory of Solids Semiconductors Diodes Transistors Thyristors

• Electric (Thermal) Properties of Solids

Conductors Outer electrons loosely bound Metals

Insulators Outer electrons tightly bound

Semiconductors At T > 0K, an electron can jump from the valence

band to the conduction band, leaving a "hole" Doping can increase conductivity dramatically

• Band Theory of Solids Atomic energy states form bands, rather than

discrete energies levels Conduction can occur when electrons occupy

the conduction band

• Fermi Level Maximum electron energy level at T = 0K Fermi function: probability a given available

electron energy state will be occupied at T

Population ~ Fermi function * density of states

• Doping Semiconductors Adding into a regular crystal lattice a small

fraction of foreign atoms N-type semiconductor: pentavalent impurity

(contributes electrons) antimony, arsenic, phosphorous

P-type semiconductor: trivalent impurity (donates electrons, producing holes) boron, aluminum, gallium

• Doped Semiconductor Bands N-type: added electrons raise the Fermi level;

easier to excite them into the conduction band P-type: holes in the band gap provide excitation

states for valence band electrons, producing mobile valence band holes

• Diodes I Unidirectional

Forward conduction

• Diodes II Rectification

Voltage Divider Voltage Divider-Rectifier

• Diodes III Power diode: eg., power supply rectifier

Maximum forward current Maximum reverse voltage Effective forward-bias resistanc

Signal diode: rectify small signals, mix frequencies (sum and difference), switch low voltages and currents Current and voltage ratings Switching speed (related to effective capacitance)

• Transistors I Switch

Off: no current On: full current

Amplifier (always on) Current Voltage

• Transistors II Types

Bipolar Junction Transistor (BJT) small current to control large current no base current, no collector-emitter current normally OFF

B

C

E

CE

B

• Transistors III Types

Field-Effect Transistor (FET) small voltage to control large current high gate voltage, CUTS OFF source-drain current normally ON/Saturated

P-ChannelN-Channel

• Transistors IV Electronically controlled variable resistors or

current amplifiers

Switch: Cut off (no collector current) vs Saturation (large collector current)

Amplifier: Active region (some collector current)

• Active Components VI Transistors: Switch

• Active Components VII Transistors: Amplifier

The collector-emitter current is controlled by the base-emitter (control) current.

• Active Components VIII Transistors: Basic amplifier circuits

Common Emitter: emitter input; collector output Common Base: emitter input; collector output Common Collector: base input; emitter output

• Active Components IX Transistors: Basic amplifier circuits

Amplifier Type Common Emitter Common Base Common CollectorPhase Shift 0 0Voltage Gain Medium High LowCurrent Gain Medium Low HighPower Gain High Low MediumInput Impedence Medium Low HighOutput Impedence Medium High Low

• Active Components X Transistors: Common source amplifier

Amplifier Type Common Emitter Common SourcePhase Shift Voltage Gain Medium HighCurrent Gain Medium Very HighPower Gain High Very HighInput Impedence Medium Very HighOutput Impedence Medium High

• Active Components XI Transistors: Insulated-Gate FET (IGFET) or

Metal Oxide Semiconductor FET (MOSFET)

• Active Components XII Transistors: IGFET / MOSFET

• Active Components XIII Thyristors: switching device used now mainly in

power supplies Pulse to gate turns on Stays on (hysteresis) until bias reversed

• Amplifiers I Increase the voltage or amplitude of signals

Differential amplifiers amplify the difference between two voltages

• Amplifiers II TypesType Input Variable

Output Variable

Input Impedence

Output impedence

Voltage Voltage Voltage High Low

Trans-conductance Voltage Current High High

Trans-resistance Current Voltage Low Low

Current Current Current Low High

Charge sensitive

Current / Charge Voltage Low Low

• Amplifiers III Frequency Ranges

Type RangeDC 0 10 Hz

Audio 10 Hz 10 kHz

RF 100 kHz 1 MHz

Video 30 1000 MHz

VHF 30 300 MHz

UHF 300 1000 MHz

Microwave 1 50 GHz

• Amplifiers IV Operational Amplifiers (op-amps)

Very high input impedence and very high gain Amplify small signals

Output from dependent voltage source proportional to Vin

non-inverting

inverting

• Amplifiers V Ideal Op-Amp

• Amplifier VI Voltage Follower

Gain = 1 Isolates circuits

• Amplifiers VII Op-Amp Inverter

Negative Gain

• Amplifiers VIII Non-Inverting Op-Amp

Positive Gain

V

• Amplifiers IX Op-Amp Differentiator

Time Derivative of Input Voltage

• Amplifiers X Op-Amp Integrator

Time Integral of Input Voltage

• Power Supplies I Specifications

Maximum Current Maximum Voltage Maximum Power

Line Regulation: Load Regulation: Transient Response and Recovery Time Temperature Coefficient:

• Power Supplies II Regulated

• Digital Electronics I Based on transistors used as switches Output inverted from base voltage Pair of transistors comprises the basic digital

switch

• Digital Electronics II Logic blocks (gates) built from switches and

inverters AND-Block

OR-Block

• Digital Electronics IIIDecimal Binary Octal Hex

0 0 0000 00 001 0 0001 01 012 0 0010 02 023 0 0011 03 034 0 0100 04 045 0 0101 05 056 0 0110 06 067 0 0111 07 078 0 1000 10 089 0 1001 11 0910 0 1010 12 0A11 0 1011 13 0B12 0 1100 14 0C13 0 1101 15 0D14 0 1110 16 0E15 0 1111 17 0F16 1 0000 20 10

• Digital Electronics IV Bit: single binary digit (0 or 1) Word: group of bits (represent a number) Byte: eight-bit word Bus array of conductors for transferring

information within