REVIEW: Microelectronics & Computer Principles

Microelectronics is a subfield of electronics. Microelectronics, as the name suggests, is related to the study and manufacture, or microfabrication, of electronic components which are very small (usually micrometre-scale or smaller, but not always). These devices are made from semiconductors. Many components of normal electronic design are available in microelectronic equivalent: transistors, capacitors, inductors, resistors, diodes and of course insulators and conductors can all be found in microelectronic devices. Unique wiring techniques such as wire bonding are also often used in microelectronics because of the unusually small size of the components, leads and pads. This technique requires specialized equipment.

Digital integrated circuits (ICs) consist mostly of transistors. Analog circuits commonly contain resistors and capacitors as well. Inductors are used in some high frequency analog circuits, but tend to occupy large chip area if used at low frequencies; gyrators can replace them in many applications.

As techniques improve, the scale of microelectronic components continues to decrease. At smaller scales, the relative impact of intrinsic circuit properties such as interconnections may become more significant. These are called parasitic effects, and the goal of the microelectronics design engineer is to find ways to compensate for or to minimize these effects, while always delivering smaller, faster, and cheaper devices

1. Monolithic integrated circuits are usually referred to as _____.

a. Silicon chipsb. Selenium rectifiersc. Germanium chipsd. Hybrids

2. Which type of component is generally not practical for fabrication in an IC?a. Resistorsb. Inductorsc. Diodesd. Capacitors

3. Which type of IC is used to determine whether voltage levels are the same or not?a. An op ampb. A timerc. A comparatord. A multiplexer/demultiplexer

4. Which of the following statements is true?a. Each LED in a common-anode display requires an active +V input to light

b. Each LED in a common-cathode display requires an active ground input to light

c. An LCD requires less power to operate than a typical LED multisegment display

d. All of the above

5. An electronic device that can be turned on and turned off by a gate pulse is called a _____.a. Bipolar junction transistorb. Silicon-controlled switchc. Silicon-controlled rectifierd. Shockley diode

Advantages of IC technology* CompactnessAn obvious asset of IC design is economy of space;

ICs are far more compact than equivalent circuits made from individual transistors, diodes, capacitors, and resistors.

A corollary to this is the fact that far more complex circuits can be built, and kept down to a reasonable size, using ICs as compared with discrete components. Thus, you see notebook computers, also known as laptops, with capabilities more advanced than early computers that took up whole rooms.

* High speedAnother corollary to the compactness of ICs is

the fact that the interconnections among components are physically tiny, making high switching speeds possible. Electric currents travel fast, but not instantaneously. The less time charge carriers need to get from component X to component Y, in general, the more computations are possible within a given span of time, and the less time is needed for complex operations.

* Low power requirementAnother advantage of ICs is that they use less

power than equivalent discrete-component circuits. This is especially important if batteries are to be used for operation. Because ICs use so little current, they produce less heat than their discrete component equivalents. This translates into better efficiency. It also minimizes the problems that plague equipment that gets hot with use, such as frequency drift and generation of internal noise.

* ReliabilityIntegrated circuits fail less often, per

component-hour of use, than appliances that make use of discrete components. This is mainly a result of the fact that all interconnections are sealed within the IC case, preventing corrosion or the intrusion of dust. The reduced failure rate translates into less downtime, or time during which the equipment is out of service for repairs.

* Ease of maintenanceIntegrated-circuit technology lowers

maintenance costs, mainly because repair procedures are simplified when failures do occur. Many appliances use sockets for ICs, and replacement is simply a matter of finding the faulty IC, unplugging it, and plugging in a new one. Special desoldering equipment is used with appliances having ICs soldered directly to the circuit boards.

* Modular constructionModern IC appliances use modular construction. In

this scheme, individual ICs perform defined functions within a circuit board; the circuit board or card, in turn, fits into a socket and has a specific purpose. Computers, programmed with customized software, are used by repair technicians to locate the faulty card in an appliance. The whole card can be pulled and replaced, getting the appliance back to the consumer in the shortest possible time. Then the computer can be used to troubleshoot the faulty card, getting the card ready for use in the next appliance that happens to come along with a failure in the same card.

Modular construction can theoretically be used with discrete-component design. But this is rarely done. When a device is sophisticated enough to need modular construction, IC design is usually needed to keep the size within reason.

6. The channel of JFET is between the _____.a. Input and outputb. Drain and sourcec. Gate and draind. Gate and source

7. To produce tin film resistors, which of the following materials is the most widely used?a. Titaniumb. Tantalumc. Nichromed. Chromium cermets

8. As the input voltage varies within specified limits, the zener diode maintains a nearly constant output voltage across its terminal. This is called _____.a. Auto regulationb. Specific regulationc. Line regulationd. Load regulation

9. The BEST choice electronic device to turn a device at a particular voltage is a/an _____.a. SCR b. SCSc. DIACd. PUT

10. _____ is a kind of oscilloscope which consist of narrowband if filter and a local oscillator (receiver) capable of showing transmitter carriers, spacing, harmonics and sidebands.a. Polygraphb. Harmonics analyzerc. Spectrum analyzerd. Computerized tomography

Limitations of IC technology* Inductors impracticalWhile some components are easy to fabricate

onto chips, other components defy the IC manufacturing process. Inductances, except for extremely low values, are one such bugaboo. Devices using ICs must generally be designed to work without inductors. Fortunately, resistance-capacitance (RC) circuits are capable of doing most things that inductance- capacitance (LC) circuits can do.

* Mega-power impossibleThe small size and low current consumption of ICs

comes with a “flip side.” This is the fact that high-power amplifiers cannot, in general, be fabricated onto semiconductor chips. High power necessitates a certain minimum physical bulk, because such amplifiers always generate large amounts of heat. This isn’t a serious drawback. Power transistors and vacuum tubes are available to perform high-power tasks. Integrated circuits are no different than anything else: they’re good at some things, and not so good at others.

11. Which of the following are UJT terminals?a. Emitterb. Basec. Base2d. Gatei. B, C and D onlyii. A, B, and C onlyiii. A, B and D onlyiv. All of the above

12. Type of semiconductor diode varies its internal capacitance as the voltage applied to its terminals varies.a. A zener diodeb. A varactor diodec. A silicon-controlled rectifierd. A tunnel diode

13. Alkaline cells are:a. Are cheaper than zinc-carbon cells

b. Are generally better in radios than zinc-carbon cells

c. Have higher voltages than zinc-carbon cells

d. Have shorter shelf lives than zinc-carbon cells

14. Which type of digital IC is least susceptible to noise?a. Transistor-transistor logicb. Base-coupled logicc. Emitter-coupled logicd. N-channel-coupled logic

15. In magnetic video tape:a. The video tracks are parallel to the edgesb. The video tracks are diagonalc. The video tracks are perpendicular to the edgesd. The video tracks can be oriented at any angle

Component densityThe number of elements per chip in an IC is

called the component density. There has been a steady increase in the number of components that can be fabricated on a single chip. Of course there is an absolute limit on the component density that can be attained; it is imposed by the atomic structure of the semiconductor material. A logic gate will never be devised that is smaller than an individual atom. Technology hasn’t bumped up against that barrier yet.

* MSIIn medium-scale integration (MSI), there are

10 to 100 gates per chip. This allows for considerable miniaturization, but it is not a high level of component density, relatively speaking. An advantage of MSI (in a few applications) is that fairly large currents can be carried by the individual gates. Both bipolar and MOS technologies can be adapted to MSI.

* LSIIn large-scale integration (LSI), there are

100 to 1000 gates per semiconductor chip. This is an order of magnitude (a factor of 10) more dense than MSI. Electronic wristwatches, single-chip calculators, and small microcomputers are examples of devices using LSI ICs. They can be 10 times more sophisticated than MSI devices.

* VLSIVery-large-scale integration (VLSI) devices

have from 1,000 to 10,000 components per chip. This is an order of magnitude more dense than LSI. Complex microcomputers, and peripheral circuits such as memory storage ICs, are made using VLSI.

16. Compact disks (CDs) are not generally used for recording:a. Voicesb. Musicc. In digital formd. Via magnetic fields

17. In which of the following places would you most likely choose a lithium battery?a. A microcomputer memory backupb. A two-way portable radioc. A portable audio cassette playerd. A rechargeable flashlight device

18. A hot-carrier diode is a diode that ____.a. Emits light when forward biasedb. Switches very fastc. Varies resistance with temperature

d. Changes its capacitance with voltage

19. Which of the following is not an advantage of CMOS?a. Relative immunity to noise pulsesb. Low-current requirementsc. Ability to work at high speedd. Ability to handle high power levels

IC memory* RAMA random-access memory (RAM) stores

binary data in arrays. The data can be addressed (selected) from anywhere in the matrix. Data is easily changed and stored back in RAM, in whole or in any part. A RAM is sometimes called a read/write memory.

There are two kinds of RAM: dynamic RAM (DRAM) and static RAM (SRAM). A DRAM employs IC transistors and capacitors, and data is stored as charges on the capacitors. The charge must be replenished frequently, or it will be lost via discharge. Replenishing is done automatically several hundred times per second. An SRAM uses a circuit called a flip-flop to store the data. This gets rid of the need for constant replenishing of charge, but the tradeoff is that SRAM ICs require more elements to store a given amount of data.

With any RAM, the data is erased when the appliance is switched off, unless some provision is made for memory backup. The most common means of memory backup is the use of a cell or battery. Modern IC memories need so little current to store their data that a backup battery lasts as long in the circuit as it would on the shelf. A memory that disappears when power is removed is called a volatile memory. If memory is retained when power is removed, it is nonvolatile.

* ROMBy contrast to RAM, read-only memory

(ROM) can be accessed, in whole or in any part, but not written over. A standard ROM is programmed at the factory. This permanent programming is known as firmware. But there are also ROMs that you can program and reprogram yourself.

* EPROMAn erasable programmable ROM (EPROM) is an IC

whose memory is of the read-only type, but that can be reprogrammed by a certain procedure. It is more difficult to rewrite data in an EPROM than in a RAM; the usual process for erasure involves exposure to ultraviolet. An EPROM IC can be recognized by the presence of a transparent window with a removable cover, through which the ultraviolet is focused to erase the data. The IC must be taken from the circuit in which it is used, exposed to the ultraviolet for several minutes, and then reprogrammed via a special process.

There are EPROMs that can be erased by electrical means. Such an IC is called an EEPROM, for electrically erasable programmable read-only memory. These do not have to be removed from the circuit for reprogramming.

20. In a ROM:a. It’s easy to get data out and put it inb. It’s hard to get data out, but easy to put it inc. It’s easy to get data out, but hard to put it ind. It’s hard to get data out or put it in

21. As the computer industry doubled the density of components every year, it became known asa. Kulinowski’s Theoryb. Paul’s Suggestionc. Moore’s Lawd. Bardeen’s Hypothesis

22. The person responsible for the researend(as is) design and development of a complete information system.a. PROGRAMMERb. PEOPLE WAREc. SYSTEM ANALYSTd. COMPUTER OPERATOR

23. An English scientist who drew up plans for the first programmable computer in 1830a. Vannevar Bushb. William Oughtredc. Charles Babbaged. Herman Hollerith

24. What do you call a concept which describes the relationship of all functional components of a computer such as CPU and input./output devices?a. Engineering developmentb. Architecturec. Prototypingd. Pre-production modeling

25. Large centralized data-processing complexes like multi-national companies, departments and corporations use which type of general-purpose computer that operates programs simultaneously?a. Mini-computerb. Microcomputerc. Main-frame computerd. Super-computer

COMPUTER – An electronic device designed to accept data, perform prescribed computational and logical operations at high speed and output the result of this operation.

Classification of Computers:* According to purposeGeneral PurposeSpecial Purpose* According to the type of technologyMechanicalElectromechanicalElectronics

* MECHANICAL COMPUTERSMechanical or analog computers are

devices used for the computation of mathematical problems.

Made up of components such as integrators, sliding racks, cams, gears, springs and driveshafts.

Their physical size depends on the number of functions the computer has to perform.

* ELECTROMECHANICAL COMPUTERSThey use electrical components to

perform some of the calculations and to increase accuracy.

The size of the computer was reducedThe components used to perform the

calculations are devices such as synchros, servos, resolvers, amplifiers, servo amplifiers.

They are special purpose computers

* ELECTRONIC COMPUTERSMathematical process were solved by

using electrical voltages only, applied to elements such as amplifiers, summing networks, differentiating and integrating circuits.

DIGITAL COMPUTER GENERATION1st GENERATIONUses vacuum tubesUses machine language2nd GENERATIONUses transistorsUses symbolic machine languages or

assembly languages3rd GENERATIONMiniaturized circuits4th GENERATIONUses LSI and VLSI

Programming Languages Types:MACHINE LANGUAGEThe program is represented by 1’s and 0’sASSEMBLY LANGUAGEUses abbreviation (OP codes) to represent

instructionsHIGH-LEVEL LANGUAGEUses English-like language to write

instructions

SOFTWARES

CATEGORIES:SYSTEM SOFTWARE (Operating System)Collection of programs which are needed

in the creation, preparation and execution of the programs.

USER SOFTWARE (Application Software)

26. The method of assigning more sectors to the outer disk tracks is referred to as _____ recording.a. Randomb. Zonec. Sectord. System

27. What is the generic term for utilities and programs needed to operate a computer system?a. Hardwareb. Softwarec. People wared. Tupper ware

28. The abbreviation FTP stands for:a. Fast Text Packetb. File Transfer Protocolc. Frequency/Time Processingd. Federal Trade Program

29. The computer worm that infected computer systems world-wide in 10 minutes, making it the fastest computer virus ever known is called _____.a. Claw Hammerb. Sledge Hammerc. SQL Hammerd. SARS Virus

30. The bit storage capacity of a Read Only Memory(ROM) with a 512 x 8 organization is _____ bits.a. 1024b. 8192c. 4096d. 2048

END OF REVIEW