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

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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