Introduction to RF & Wireless - Part 2

transcript

Introduction to RF & Wireless

Two Day Seminar

Module 2

Introduction to RF & Wireless

Two Day Seminar

Module 2

Course AgendaDay One

• Morning (Module 1)– Introduction to RF

• Afternoon (Module 2)– RF hardware

Day Two• Morning (Module 3)

– Older systems & mobile telephony

• Afternoon (Module 4)– Newer systems & the future

Module 2 - RF Hardware

1. Basic Building Blocks

2. Other Components

3. Circuits

2. Other Components

3. Circuits

Transmitter/Receiver Preview

Antennas

Amplifiers

Filters

Mixers

Sources

Transmitter/Receiver Review

Transmitter/Receiver PreviewAntennas

Amplifiers

Filters

Mixers

Sources

Basics Building Blocks - Transmitter/Receiver Preview

Transmitters & Receivers

Recall

Transmitter Block Diagram

Receiver Block Diagram

AntennasAmplifiers

Filters

Mixers

Sources

Basic Building Blocks - Antennas

Antennas

Function Turn current on a wire into airborne waves Vice versa

• Most antennas work in both directions

Antennas

What Act as impedance matching circuits

• From conductor (50 ohms) to free space (377 ohms)

Free space377 ohms

Conductor50 ohms

Antenna

Antennas

How Conductors that are about ½ wavelength long

begin to radiate RF energy as waves

½ Wavelength

Wavelengths Wavelength (meters) Application

5,000,000 Electrical wall outlet

152,500 The human voice

566 AM radio

5 VHF television

3 FM radio

0.3 Cellular phones

0.1 PCS phones

0.02 DirectTV

Antennas

Characteristics Active: Requires a power supply Passive: Does not require a power supply Directional: Sends RF energy in one direction Omnidirctional: Sends RF energy in all directions Size: Depends on the wavelength Shape: Depends on the direction of the RF energy

Antenna Pattern

What Is It? An engineering tool that shows a birds-eye view of

the RF energy radiating out of an antenna

Antenna Pattern

Omnidirectional

Antenna Pattern

Directional

Beamwidth

Azimuth

Two Kinds Power gain

• Comes from an amplifier

• Increases the power

Antenna gain• Directional gain

• No increase in power

Isotropic Antenna

What Is It? A mythical "point" antenna

• Antenna pattern is a sphere• Minimum power density

Directional Antenna

Visual Depiction Higher power density

than isotropic

Antenna Gain

Directional Gain A gain in power density NOT power

• Relative to an isotropic antenna

Measured in dBi

Definition dBi = "dB greater than isotropic"

Antenna Gain

For ExampleAn directional antenna with 10 dBi of antenna gain produces an RF signal with TEN TIMES the power density compared to an isotropic antenna

Antenna Gain

Input power = 30 dBm

Output power =10 dBi

30 dBm

Effective Isotropic Radiated Power = 30 dBm + 10 dBi = 40 dBm

Noise floor -120 dBm

Output power40 dBm

Free space loss

-80 dBm

120 dB

Absorption-90 dBm

30 dBS/N

Effective isotropicradiated power 40 dBm

Free space loss

-80 dBm

120 dB

Absorption-90 dBm

30 dBS/N

Effective isotropicradiated power 40 dBm

Free space loss

-80 dBm

120 dB

Absorption 10 dB

40 dBS/N

Ant gain

Antenna Gain

30 dBm Antenna10 dBi

Antenna10 dBi

FSL-120 dB

Absorb-10 dB

-80 dBm

40 dBS/N

Antenna Gain

Even Omnidirectionals Have Gain 2 - 3 dBi

Antenna Types

Omnidirectional Dipole: ½ wavelength long Monopole: ¼ wavelength long

Directional Dish Horn Patch Array

Array Antenna

Polarization

What Is It? The RF (sine) waves which emanate from an

antenna have an orientation to them• Horizontal

• Vertical

Polarization

Horizontal Vertical

Polarization

So What Otherwise identical RF signals can be made

distinct by having different polarizations• Better use of scarce bandwidth

• Polarization diversity

Smart Antennas

What Are They? Directional antennas in which the antenna beam moves

Smart Antennas

How? Switched beam Electronically scanned

Why? More users per area Spatial division multiple access

Antennas

AmplifiersFilters

Mixers

Sources

Basic Building Blocks - Amplifiers

Amplifiers

Function Increase the power of RF signals

• "Power gain"

Amplifiers

Main Types Low noise amplifier (LNA)

• First one in a receiver

High power amplifier (HPA)• Last one in a transmitter

Other• Many different kinds

• "Gain blocks"

Amplifiers

HPA LNA

Amplifier Properties

LNA Gain Linearity Noise figure

HPA Gain Linearity Output power

Power Gain (Gp) Measured in dB

-90 dBm

-60 dBm

Linearity

Transfer CurveOne dB compression point

Linearity

Another Measure Third order intercept (Ip3)

Intercept point• Measured in dB

Output Power

Dictates Amplifier Performance Suppose Psat = 40 dBm

20 dBm

50 dBm

Output Power

20 dBm

50 dBm

Output Power

20 dBm

40 dBm

Output Power

20 dBm

40 dBm

Noise Figure

Definition How much an amplifier decreases the S/N ratio

• Measured in dB

NF=3dB40 dBS/N 37 dBS/N

A Special Amplifier

Variable Gain Amplifier (VGA) Gain can be made to vary

A Special Amplifier

Variable Gain Amplifier (VGA) Gain can be made to vary

Antennas

Amplifiers

FiltersMixers

Sources

Basic Building Blocks - Filters

Filters

Function Eliminate signals at unwanted frequencies

Filters

Block Diagrams

Filters

Frequency Response Used to describe a filter's behavior A graph of attenuation vs frequency

Filters

Types Low pass

• Only signals below a certain frequency can pass

High pass• Only signals above a certain frequency can pass

Band pass• Only signals between two frequencies can pass

Band reject ("Notch")• Only signals outside two frequencies can pass

Low Pass Filter

Ideal Frequency Response

Pass band

Stop band

Low Pass Filter

Real Frequency Response

Pass band

Stop band

Low Pass Filter

Real Frequency Response

Out of band signalsIdealpassband

High Pass Filter

Frequency Response

Band Pass Filter

Frequency Response

Band Reject Filter

Frequency Response

Special Filters

Duplexer ("Diplexer") Two band pass filters in one package

Special Filters

Duplexer Frequency Response

Special Filters

SAW (Surface Acoustic Wave) Converts RF signals into sound signals Used for low frequency applications

• Typically less than 3 GHz

Very small and low cost• Ideal for use in cell phones

Special Filters

Superconducting Filters Have zero insertion loss in the pass band Have a near-vertical frequency response Require cooling units

• Used primarily in cellular base station receivers

Basics Building Blocks - Filters

Filters

Interesting Things To Know All devices have a 1 dB compression point -

even passive ones like filters• A function of input power

IL of a passive device is its noise figure

Antennas

Amplifiers

Filters

MixersSources

Basics Building Blocks - Mixers

Mixers

Function To change the frequency of the RF signal

Mixers

How Mixers have two inputs and one output called ports

Input 1

Input 2

Output

Mixers

How One RF signal goes into Input 1 One RF signal goes into Input 2 TWO RF signals come out of the Output

Mixers

How Output signal 1

• Frequency = sum of frequencies of input signals

Output signal 2• Frequency = difference of frequencies of input signals

Mixers

ExampleOne input signal to a mixer has a frequency of 400 MHz while the other has

a frequency of 500 MHz. What is the frequency of the two output signals?

Frequency (signal 1) = 400 MHz + 500 MHz = 900 MHz

Frequency (signal 2) = 500 MHz - 400 MHz = 100 MHz

Mixers

Example

500 MHz

400 MHz

100 MHz

900 MHz

Mixers

What Mixers can be used to raise OR lower the

frequency of an RF signal• Raise: upconverter and it's in a transmitter

• Lower: downconverter and it's in a receiver

Only one output signal is used The other is eliminated with a filter

Mixers

Characteristics Noise figure Insertion loss called conversion loss (CL) One dB compression point Ports have designations

Mixers

Port Designations

Mixers

Port Designations LO is always one of the inputs

• LO: Local Oscillator

RF/IF can be input or output• IF: Intermediate Frequency• Upconverter (transmitter): RF is output• Downconverter (receiver): RF is input

Mixers

How They're Actually Used Upconverters/Downconverters

• Change the frequency

Phase modulators/demodulators• Impart or detect a phase shift

Mixers

Downconverter Superheterodyne

RF Signal900 MHz

Baseband Signal64 KHzIF Signal

70 MHz

From Antenna To Demod

Antennas

Amplifiers

Filters

Mixers

Sources Transmitter/Receiver Review

Basics Building Blocks - Sources

Sources

Function To generate a perfect sine wave at a specified

frequency• It is the "source" of the RF• It is also called an oscillator• It feeds the LO port of a mixer

Sources

How Many materials produce a sine wave when

excited with electrical energy

What The objective is to produce the most perfect

sine wave possible

Sources

Examples

Acronym Oscillator

DRO Dielectric resonator

XO Crystal

YIG Yttrium Iron Garnet

Special Sources

Voltage Controlled Oscillator (VCO) The frequency of the sine wave can be made to

vary by means of an external control

Control voltage in

Sine wave out

Special Sources

Synthesizer "Sophisticated" oscillator

Frequency selector

RecapAntenna Airborne waves to current

Amplifer Makes signals bigger

Filter Elliminates unwanted frequencies

Mixer Changes a signal’s frequency

Source Produces a perfect sine wave

Antennas

Amplifiers

Filters

Mixers

Sources

64 Kbps

64 KHz

900 MHz

70 MHz

900 MHz

Signals

900 MHz

64 KHz

70 MHz

64 KHz

64 Kbps

Basic Building Blocks

The end

2. Other Components

3. Circuits

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers

Circulators/Isolators

Transformers

Detectors

Phase Shifters/Detectors

2. Other Components

SwitchesAttenuators

Dividers/Combiners

Couplers

Transformers

Detectors

Other Components - Switches

Switches

Function Switch an RF signal's path

Switches

Function Change an RF signal's path

Switches

Cell phone

Switches

Cell phone

Switch Types

Switch Type Characterstics

Solid state FastSmall

Inexpensive

Electromechanical BigSlow

Low insertion loss

Insertion Loss vs Isolation

Insertion Loss Loss in the closed path

Insertion loss 1 dB

Insertion Loss vs Isolation

Isolation Loss in the open path

Isolation 30 dB

2. Other Components

Switches

Attenuators Dividers/Combiners

Couplers

Transformers

Detectors

Other Components - Attenuators

Attenuators

Function To make an RF signal smaller

Attenuators

Block Diagrams

Attenuator Types

Attenuator Type Characterstics

Fixed Insertion loss has asingle value

Voltage Variable Insertion loss can take anyvalue over a range

Digital Insertion loss can only takecertain values over a range

Digital Attenuator

Saturated Power Suppose Psat = 40 dBm

20 dBm

50 dBm

Recall

Attenuators

Where To prevent saturation

2. Other Components

Switches

Attenuators

Dividers/Combiners Couplers

Transformers

Detectors

Other Components - Dividers

Dividers

Function Break up an RF signal into 2 or more signals

Dividers

30 dBm

Dividers

30 dBm

26 dBm

Other Components - Combiners

Combiners

Function Combine 2 or more RF signals into one

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers Circulators/Isolators

Transformers

Detectors

Couplers

Coupler Types Also Called

Directional coupler Coupler

Bi-directional coupler Dual directional coupler

Quad coupler Quadrature couplerQuadrature (Quad) hybrid

HybridLange coupler

Other Components - Couplers

Directional Couplers

Function To "sample" an RF signal

Bi-Directional Couplers

Function To sample reflected power also

Quad Couplers

Function Splits a signal into 2 with a phase shift

Quad Couplers

Where Balanced amplifier

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers

Circulators/Isolators Transformers

Detectors

Other Components - Circulators

Circulators

Function Reroutes RF signals

Circulators

Cell phone

Other Components - Isolators

Isolators

Function To protect something from reflected power

Other Components - Isolators

Isolators

Base stationLoad

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers

Transformers Detectors

Other Components - Transformers

Transformers

Function Impedance matching, coupling, and others

RF outRF in

Other Components - Transformers

75 ohms 50 ohms

Impedance matching circuit

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers

Transformers

Detectors Phase Shifters/Detectors

Other Components - Detectors

Detectors

Function To convert RF power to voltage

RF in Voltage out

2. Other Components

Switches

Attenuators

Dividers/Combiners

Couplers

Transformers

Detectors

Other Components - Phase Shifters

Phase Shifters

Function To phase shift the output relative to the input

Input signalPhase shiftedoutput signal

Other Components - Phase Shifters

Phase Shifters

Where In modulators

Other Components - Phase Detectors

Phase Detectors

Function To convert a phase difference to a voltage

Where In demodulators

PhaseDetector

RF Input 1

RF Input 2Voltage Output

RecapSwitch Change an RF signals’ path

Antennuator Makes signals smaller

Divider/Combiner

Splits a signal evenly

Coupler Samples a signal

Quad Coupler Splits a signal with phase shift

RecapCirculator/

IsolatorReroutes a signal

Transformer Impedance matching, coupling, etc

Detector Converts an RF signal to a voltage

Phase Shifter Imparts a phase shift on a signal

PhaseDetector

Converts a phase diff to a voltage

PhaseDetector

Other Components

The end

3. Circuits

Semiconductors

Circuit Technologies

Interconnection

3. Circuits

Semiconductors

Interconnection

Circuits - Seminconductors

Semiconductor MaterialsMaterial Comments

Silicon(Si)

Low costLow frequency

Gallium Aresenide(GaAs)

Higher costHigher frequency

Silicon Germanium(SiGe)

Low costHigh effeciency

Indium Phosphide(InP)

Highest costHighest frequency

Semiconductor Building BlocksComponent Usage

Diode Switches, AttenuatorsMixers, Detectors

Transistor Amplifers, SwitchesOscillators, Mixers

Integrated Circuit Combine multiplecomponents

Diodes

Main Structures PIN

• Power

Schottky• Speed

Diodes

Transistors

Main Structures Bipolar Junction (BJT)

• Low frequency

• High power

Field Effect (FET)• High frequency

• Low noise

Bipolar Junction Transistors

Materials Silicon

• "Bipolar"

Gallium Arsenide• Heterojunction Bipolar Transistor (HBT)

Field Effect Transistors

Materials Silicon

• MOSFET

• LDMOS

Gallium Arsenide• MESFET

• HEMT

• PHEMT

Transistors

Integrated Circuits

MMIC Microwave Monolithic Integrated Circuit

• Si, SiGe or GaAs

• Transistors + other components– Amplifiers

– Switches

– Digital attenuators

– Mixers

Integrated Circuits

RecapMaterials

Silicon - Low frequency Gallium Arsenide - Higher frequency Silicon Germanium - High efficiency Indium Phosphide - Highest frequency

Building Blocks Diodes - PIN, Schottky Transistors - BJT, FET Integrated circuits - Combination

3. Circuits

Semiconductors

Interconnection

Circuits - Circuit Technologies

Circuit Designs

Two Types Lumped element Distributed

Dictated By Frequency

Circuit Designs

Lumped Element Uses discrete ("real")

passive components• Inductors

• Capacitors

• Couplers

• Transformers

Circuit Designs

Distributed Uses metal traces as

passive components• Inductors

• Capacitors

• Couplers

• Transformers

Circuit ConstructionFour Ways

Discrete Hybrid MMIC Cavity

Dictated By Cost Size Performance

Circuit Construction

Discrete Packaged semiconductors Lumped passives Printed circuit board

Hybrid Packaged or bare

chip semiconductors Lumped or

distributed passives Ceramic substrate

MMIC Semiconductors

devices Distributed passives On a single piece of

semiconductor

Cavity A hollow container Signals move as waves

inside Used for high power

RecapCircuit Design

Lumped - Low frequency Distributed - High frequency

Circuit Construction Discrete - High power, quick design time Hybrid - High frequency, best performance MMIC - Small size, high volume Cavity - Very high power

3. Circuits

Semiconductors

Interconnection

Transmission lines

Circuits - Interconnection

Interconnection

Transmission Lines Should be 50 ohms (i.e. good match) Have insertion loss Effect system performance Can be made several different ways

Transmission Lines

Can Be Made Using1) Cables - box to box

2) Waveguides - high power box to box

3) Metal traces - low power, inside a box

Cables

Coaxial Cables

Inner conductor

Insulator

Outer shield

Cable Assemblies

Consist Of Coaxial cable Connectors

Cables

Connectors Many families

• Price

• Performance

• Evolution

Many types• Usage

dependent

Cables

How To Interconnect Different Families Adapters

Waveguides

What Rectangular metal

tubing

How Signals travel as

Why Zero insertion loss

Traces

Where On printed circuit boards

Traces

Where In hybrids

Traces

Where As part of MMICs

TracesConstruction

Stripline Microstrip Coplanar waveguide Metal

Substrate

RecapTransmission Lines

Coaxial cables

Waveguide

Traces

Circuits

The end

Module 2 -RF Hardware

The end

Dinner

Introduction to RF & Wireless - Part 2

Technology