Analog Enhanced Digital Performance

8/8/2019 Analog Enhanced Digital Performance

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IN THE DIGITAL-ORIENTED ERA,

DO WE REALLY NEED ANALOG

CIRCUIT DESIGN?

Muhammad Taher Abuelmaatti

King Fahd University of Petroleum and Minerals

Box 203 Dhahran 31261 Saudi Arabia

[email protected]


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WHAT IS SAID?

Analog design is old fashion and out of date. Analog design is a kind of classic art in a rapidly

changing world of electronics. The powerful electronic revolution is toward DSP

rather than ASP. It is not wise to select analog design as a career. It is not wise to select analog design courses.

Analog designers are not considered the heroesof the modern internet and HDTV technology. Analog design is used only in high voltage area. The world has gone digital and analog is old.


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Examples: Digital Camera

Analog chips translate wavelengths and

intensities into digital code.

To check the image, the cameraretranslate the digital code into a visual

display.


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Examples: Portable Receiver

Design

A mostly digital receiver architecture:

Go digital at the earliest possible stage

AnalogFront-End

A/DConverter

DigitalBaseband

Processing

RFFilter

Custom Analog IC Custom Digital IC
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Receiver Block Diagram

RF toBasebandHigh

Speed

A/D

RFFilter

Analog IC

Carrier and

Timing Sync.

Channel

Estimation

AdaptiveMultiuser

Detection

Data Out3.3 Mbps

Digital IC


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Analog RF Design

x

x

090

o

o

LNA AGC

fosc

In Phase(I)

Quadrature(Q)

RF Filter

A/D

A/D


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Transceivers


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Basic Analog Building Blocks:

1. Amplifiers (Power Amplifiers, Voltage Amplifiers: AF, RF, VF ) 2. Oscillators (sinusoidal and others) 3. Filters 4. Clocks 5. Analog-to-Digital and Digital-to-Analog Converters.

6. Modulators (FSK, PSK, ASK, Amplitude, Phase, FrequencyModulation)

7. Demodulators 8. Mixers 9. Phase Locked Loops

10. Multiplexers. 11. Duplexers


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The Reality

No human experiences reality as a pattern

of 1s and 0s.

The natural world is analog with endlessly

variable waves of sound and light,

temperature and pressure fluctuations,

and shifting magnetic fields.

Digital revolution drives a strong demand

for advances in analog electronics.


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ADVANTAGES OF DIGITAL

CIRCUIT DESIGN

Robustness; two signal levels.

Simple and cheap to design; well developedCAD software.

Very suitable for integration. Offers high precision.

Programmability can be easily obtained.

Easy to design at system level. Have a cycle/success ratio near unity.


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ADVANTAGES OF ANALOG

CIRCUIT DESIGN

Efficient use of bandwidth.

Simple; no S/H, A/D and D/A.

Lower power consumption; uses fewer transistors.

Low cost; smaller silicon chips.

Power efficient.

Uses physical properties of transistors.


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WHEN AND WHERE ANALOG

CIRCUIT DESIGN IS NEEDED?

To interface a DSP with the input sensors.

To interface a DSP with the output actuators.

In low precision systems; analog neural

networks.

In high frequency systems.

In enhancing the performance of digital circuits.

On the average, there is probably 15 analogchips needed for every digital processor.


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ANALOG ENHANCED DIGITAL

PERFORMANCE

Enhancing the performance of the hard diskdrive; by reshaping distorted high speed digitalpulses.

High speed digital circuits are partly analog!Relatively large rise and fall times.

In memory chips and microprocessor chipsentire analog blocks; such as amplifiers and

PLLs are used. High frequency clocks.


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Digital Enhanced Analog

Performance

Analog microchip performance can be improvedby integrating them with digital monitoring andcontrol circuits.

The line between pure digital and pure analogchips is rapidly blurring, with both incorporatinga little bit of the other.

That is Mixed Mode. Experts with feet in bothrealm are especially valuable.


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MIXED ANALOG AND DIGITAL

CIRCUITS

Advantages

1. Reduced system size.

2. Reduced power dissipation.3. Increased speed of operation.

4. Increased design flexibility.

5. Increased reliability.6. Reduced system cost.


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A combination of high dynamic range, high

speed and acceptable low power dissipation

is a challenge for MAD circuits.

Analog neural networks. Field programmable analog arrays.

Radio frequency circuits.

Analog image processing.

Disk drive electronics. Fuzzy logic.

Chaotic circuits and systems.

CURRENT RESEARCH IN

MAD CIRCUITS


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WHERE MAD CIRCUITS ARE

USED?Almost in every broad application where chips are used.

Examples include:

1. Telecommunications: transmission, reception,switching

2. Consumer electronics: audio, video,3. Computers and related equipment: disk drives, LAN

transmitters and receivers,..

4. Automotive systems: engine control, safety

equipment,5. Biomedical instrumentation: hearing aids, cardiac

pacemakers,

6. Robotics: interfaces to sensors and actuators.


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FUTURE OF ANALOG The world around us is essentially analog.

Our senses are organized for communicating with this world.

Analog circuit design is indispensable and irreplacable.

The future of analog circuit design is very dynamic and holds

many opportunities.

It takes six to nine months for a college graduate to be

productive in digital engineering.

It takes a Ph.D. holder four years to be productive in the analog

area.


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How to Enhance the Image of

Analog Circuit DesignThe lack of interest in analog circuit design could be explained by:

1. Inadequate teaching of the subject. Only teachers with provenexpertise in the area can teach Electronic Circuits courses.

2. Extensive mathematical manipulations and/or use of the black

box approach. This should be minimized and emphasis should beon the physical meaning of the equations.

3. The lack of understanding of circuits at the voltage and currentlevels.

4. Extensive use of simulation and software packages. Moreemphasis on experimental work is needed. Simulation is not a

bad thing, but engineering students must feel the real world.5. Wrong advises and the advertising media.


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CONCLUSION

Analog circuit design is here to stay.

Imagine the effect on the digital world of a

complete embargo of data converters and

signal-conditioning components by thesmall analog nation.

Analog designers need not leave town.


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Analog Enhanced Digital Performance