Basic Electronics - George Mason Universityphysics.gmu.edu/~rubinp/courses/407/electronicsslides.pdfBasic Electronics Review Linear (Ohmic) Components Non-Linear Components Amplifiers

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●

● 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 Wirewound Surface

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 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

Type 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 RangesType 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

● 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 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

– 0 [NULL]– 1 [IDENTITY]– A; B– AB [AND]– A+B [OR]– A, B

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

– AB (or A•B) [AND]; A+B [OR]; A (NOT A) [Complement (inversion)]

● Functions– AB, AB– AB [NAND]– A+B [NOR]– A+B, A+B– AB+AB [XOR]– 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

●

● Number of states per unit volume per differential element

●

●