Basic Electronics

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

Review I

● I [A] = ΔQ [C] / Δt [s] A ≡ Cs-1

● To measure current through a component, connect an ammeter in series with it ● EMF [V] = ΔE [J] / ΔQ [C] V ≡ JC-1

● To measure potential difference across a component, connect a voltmeter in parallel with it

● P [W] = ΔE [J] / Δt [s] = IV W ≡ Js-1

Review II

● Ohm's Law: V = IR ● Kirchhoff's Rules

● Loop Rule: Σ(voltage drops around a closed loop) = Σ(voltage sources) ● Node Rule: Σ(current into a node) = Σ(current out of a node)

Review III

● Resistance R [Ω]: 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

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● Impedance (frequency dependent)

● Combine like resistance

Component Selection Criteria Choosing 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

Carbon Surface Type Metal Film Wirewound Film Mount

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

Power 0.0125- 0.125-2W 0.1-5W 1-200W Rating 0.25W

Temp 250-450 10-350 20-400 25-200 Coefficient ppm/K ppm/K ppm/K 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 Coaxial Microstrip Strip Line Cable (Triplate)

Characteristic Impedances, Z 0 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

C

B

E C

B

E

Transistors III

● Types

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

N-Channel P-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 Collector Phase Shift π 0 0 Voltage Gain Medium High Low Current Gain Medium Low High Power Gain High Low Medium Input Impedence Medium Low High

Output Impedence Medium High Low Active Components X

● Transistors: Common source amplifier

Amplifier Type Common Emitter Common Source Phase Shift π π Voltage Gain Medium High Current Gain Medium Very High Power Gain High Very High Input Impedence Medium Very High

Output 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

● Types Input Output Input Output Type Variable Variable Impedence impedence Voltage Voltage Voltage High Low Trans- Voltage Current High High conductance Trans- Current Voltage Low Low resistance Current Current Current Low High Charge Current / Voltage Low Low sensitive Charge Amplifiers III

● Frequency Ranges Type Range DC 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 non-inverting

● Output from dependent

voltage source inverting proportional to Vin

●

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 III Decimal Binary Octal Hex 0 0 0000 00 00 1 0 0001 01 01 2 0 0010 02 02 3 0 0011 03 03 4 0 0100 04 04 5 0 0101 05 05 6 0 0110 06 06 7 0 0111 07 07 8 0 1000 10 08 9 0 1001 11 09 10 0 1010 12 0A 11 0 1011 13 0B 12 0 1100 14 0C 13 0 1101 15 0D 14 0 1110 16 0E

15 0 1111 17 0F 16 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 the computer. ● Baud - bits/second

Digital Electronics V

● Digital Logic: 2 Bits; 3 Operations; 16 Functions

● Operations – AB (or A•B) [AND]; A+B [OR]; A (NOT A) [Complement (inversion)] ● Functions – 0 [NULL] – AB, AB – 1 [IDENTITY] – AB [NAND] – A; B – A+B [NOR] – AB [AND] – A+B, A+B – A+B [OR] – AB+AB [XOR] – – A, B AB+AB [XNOR] Digital Electronics VI

● Basic Gates and Truth Tables

Digital Electronics VII

● Combinational Operations

● Outputs depend only on current input states – AND, OR, Inverter gates – NAND and NOR gates – XOR gate: A OR B, but NOT (A AND B) – XNOR gate: (A AND B) OR (NOT A AND NOT B)

Digital Electronics VIII

● Sequential Operations

● Carried out by two-state devices (multivibrators) – Bistable (flip-flop) – Astable – Monostable (one-shot)

Digital Electronics IX

● Flip-flops (Bistable Multivibrator)

● Digital data storage and transfer ● Registers

Digital Electronics X

● Flip-Flops

● Set/Reset (RS) – Holds state until reset

Digital Electronics XI

● Flip-Flops

● JK – Like RS, but with no ambiguous states – Also can be toggled

Digital Electronics XII

● Flip-Flops

● D – Stores values on data line

Digital Electronics XIII

● Flip-Flops

● T – Toggles output

Digital Electronics XIV

● Binary Counter

Digital Electronics XV

● Data Transfer

Digital Electronics XVI

● Astable Multivibrator

● Not stable in either state

Digital Electronics XVII

● One-shot (Monostable Multivibrator)

● Produces a single output pulse whose length is determined by the value of the resistor and capacitor.

Grounds and Grounding I

● A current return path through the earth

● National Electrical Code: a conductive pipe or rod driven into the earth to a minimum depth of 8 feet ● Any type of current return path to an energy source

Grounds and Grounding II

● Power supply grounding error

● Dual polarity configuration

Grounds and Grounding III

● Other current return configurations

Grounds and Grounding IV

● Safety hazard

● Leakage (unintended resistive path) + floating or chassis return → potential difference between return and earth

Grounds and Grounding V

● Noise (typically AC power pickup)

Grounds and Grounding VI

● Noise

● Coupling Capacitance

Grounds and Grounding VII

● Noise

● Multiple ground points – Ground loop – Ground missing

Grounds and Grounding VIII

● Single-point grounding

● Ground bus

Grounds and Grounding IX

● Analog and digital circuits should be grounded separately, then connected at a single point

Circuit Theory I

● Apply linear circuit theory to devices whose output is directly proportional to the applied input ● If possible, piecewise linearize non-linear response curves

Electronic Properties of Solids

● Behavior of electrons (and holes): Fermi statistics ● Periodic lattice of crystalline solids: “free” electrons contained in energy bands ● Scattering and absorption/emission of phonons (vibrational quanta)

Fermi-Dirac Distribution

● Number of cells in a differential volume of phase space

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● Number of states per unit volume per differential element

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