semiconducter diodes

Space charge capacitance C_T of diode:

Reverse bias causes majority carriers to move away from the junction, thereby creating more ions. Hence the thickness of depletion region increases. This region behaves as the dielectric material used for making capacitors. The p-type and n-type conducting on each side of dielectric act as the plate. The incremental capacitance C_T is defined by

Since

Therefore, (E-1)

where, dQ is the increase in charge caused by a change dV in voltage. C_T is not constant, it depends upon applied voltage, there fore it is defined as dQ / dV.

When p-n junction is forward biased, then also a capacitance is defined called diffusion capacitance C_D (rate of change of injected charge with voltage) to take into account the time delay in moving the charges across the junction by the diffusion process. It is considered as a fictitious element that allow us to predict time delay.

If the amount of charge to be moved across the junction is increased, the time delay is greater, it follows that diffusion capacitance varies directly with the magnitude of forward current.

(E-2)

Relationship between Diode Current and Diode Voltage

An exponential relationship exists between the carrier density and applied potential of diode junction as given in equation E-3. This exponential relationship of the current i_D and the voltage v_D holds over a range of at least seven orders of magnitudes of current - that is a factor of 10⁷.

(E-3)

Where,

i_D= Current through the diode (dependent variable in this expression)
v_D= Potential difference across the diode terminals (independent variable in this expression)
I_O= Reverse saturation current (of the order of 10^-15 A for small signal diodes, but I_O is a strong function of temperature)
q = Electron charge: 1.60 x 10^-19 joules/volt
k = Boltzmann's constant: 1.38 x l0^-23 joules /° K
T = Absolute temperature in degrees Kelvin (°K = 273 + temperature in °C)
n = Empirical scaling constant between 0.5 and 2, sometimes referred to as the Exponential Ideality Factor

The empirical constant, n, is a number that can vary according to the voltage and current levels. It depends on electron drift, diffusion, and carrier recombination in the depletion region. Among the quantities affecting the value of n are the diode manufacture, levels of doping and purity of materials. If n=1, the value of k T/ q is 26 mV at 25°C. When n=2, k T/ q becomes 52 mV.

For germanium diodes, n is usually considered to be close to 1. For silicon diodes, n is in the range of 1.3 to 1.6. n is assumed 1 for all junctions all throughout unless otherwise noted.

Equation (E-3) can be simplified by defining V_T =k T/q, yielding

(E-4)

At room temperature (25°C) with forward-bias voltage only the first term in the parentheses is dominant and the current is approximately given by

(E-5)

The current-voltage (l-V) characteristic of the diode, as defined by (E-3) is illustrated in fig. 1. The curve in the figure consists of two exponential curves. However, the exponent values are such that for voltages and currents experienced in practical circuits, the curve sections are close to being straight lines. For voltages less than V_ON, the curve is approximated by a straight line of slope close to zero. Since the slope is the conductance (i.e., i / v), the conductance is very small in this region, and the equivalent resistance is very high. For voltages above V_ON, the curve is approximated by a straight line with a very large slope. The conductance is therefore very large, and the diode has a very small equivalent resistance.

Fig.1 - Diode Voltage relationship

The slope of the curves of fig.1 changes as the current and voltage change since the l-V characteristic follows the exponential relationship of relationship of equation (E-4). Differentiate the equation (E-4) to find the slope at any arbitrary value of v_Dor i_D,

(E-6)

This slope is the equivalent conductance of the diode at the specified values of v_D or i_D.

We can approximate the slope as a linear function of the diode current. To eliminate the exponential function, we substitute equation (E-4) into the exponential of equation (E-7) to obtain

(E-7)

A realistic assumption is that I_O<< i_D equation (E-7) then yields,

(E-8)

The approximation applies if the diode is forward biased. The dynamic resistance is the reciprocal of this expression.

(E-9)

Although r_d is a function of i_d, we can approximate it as a constant if the variation of i_D is small. This corresponds to approximating the exponential function as a straight line within a specific operating range.

Normally, the term R_f to denote diode forward resistance. R_f is composed of r_d and the contact resistance. The contact resistance is a relatively small resistance composed of the resistance of the actual connection to the diode and the resistance of the semiconductor prior to the junction. The reverse-bias resistance is extremely large and is often approximated as infinity.

Temperature Effects:

Temperature plays an important role in determining the characteristic of diodes. As temperature increases, the turn-on voltage, v_ON, decreases. Alternatively, a decrease in temperature results in an increase in v_ON. This is illustrated in fig. 2, where V_ON varies linearly with temperature which is evidenced by the evenly spaced curves for increasing temperature in 25 °C increments.

The temperature relationship is described by equation

V_ON(T_New ) � V_ON(T_room) = k_T(T_New � T _room) (E-10)

Fig. 2 - Dependence of iD on temperature versus vD for real diode (kT = -2.0 mV /°C)

where,

T_room= room temperature, or 25°C.
T_New= new temperature of diode in °C.
V_ON(T_room ) = diode voltage at room temperature.
V_ON (T_New) = diode voltage at new temperature.
k_T = temperature coefficient in V/°C.

Although k_T varies with changing operating parameters, standard engineering practice permits approximation as a constant. Values of k_T for the various types of diodes at room temperature are given as follows:

k_T= -2.5 mV/°C for germanium diodes
k_T = -2.0 mV/°C for silicon diodes

The reverse saturation current, I_O also depends on temperature. At room temperature, it increases approximately 16% per °C for silicon and 10% per °C for germanium diodes. In other words, I_O approximately doubles for every 5 °C increase in temperature for silicon, and for every 7 °C for germanium. The expression for the reverse saturation current as a function of temperature can be approximated as

(E-11)

where K_i= 0.15/°C ( for silicon) and T1 and T2 are two arbitrary temperatures.

semi conductors

The symbol of diode is shown in fig. 4. The terminal connected to p-layer is called anode (A) and the terminal connected to n-layer is called cathode (K)

Fig.4

Reverse Bias:

If positive terminal of dc source is connected to cathode and negative terminal is connected to anode, the diode is called reverse biased as shown in fig. 5.

Fig.5

When the diode is reverse biased then the depletion region width increases, majority carriers move away from the junction and there is no flow of current due to majority carriers but there are thermally produced electron hole pair also. If these electrons and holes are generated in the vicinity of junction then there is a flow of current. The negative voltage applied to the diode will tend to attract the holes thus generated and repel the electrons. At the same time, the positive voltage will attract the electrons towards the battery and repel the holes. This will cause current to flow in the circuit. This current is usually very small (interms of micro amp to nano amp). Since this current is due to minority carriers and these number of minority carriers are fixed at a given temperature therefore, the current is almost constant known as reverse saturation current I_CO.

In actual diode, the current is not almost constant but increases slightly with voltage. This is due to surface leakage current. The surface of diode follows ohmic law (V=IR). The resistance under reverse bias condition is very high 100k to mega ohms. When the reverse voltage is increased, then at certain voltage, then breakdown to diode takes place and it conducts heavily. This is due to avalanche or zener breakdown. The characteristic of the diode is shown in fig. 6.

Fig.6

Forward bias:

When the diode is forward bias, then majority carriers are pushed towards junction, when they collide and recombination takes place. Number of majority carriers are fixed in semiconductor. Therefore as each electron is eliminated at the junction, a new electron must be introduced, this comes from battery. At the same time, one hole must be created in p-layer. This is formed by extracting one electron from p-layer. Therefore, there is a flow of carriers and thus flow of current.

A pure silicon crystal or germanium crystal is known as an intrinsic semiconductor. There are not enough free electrons and holes in an intrinsic semi-conductor to produce a usable current. The electrical action of these can be modified by doping means adding impurity atoms to a crystal to increase either the number of free holes or no of free electrons.

When a crystal has been doped, it is called a extrinsic semi-conductor. They are of two types

• n-type semiconductor having free electrons as majority carriers

• p-type semiconductor having free holes as majority carriers

By themselves, these doped materials are of little use. However, if a junction is made by joining p-type semiconductor to n-type semiconductor a useful device is produced known as diode. It will allow current to flow through it only in one direction. The unidirectional properties of a diode allow current flow when forward biased and disallow current flow when reversed biased. This is called rectification process and therefore it is also called rectifier.

How is it possible that by properly joining two semiconductors each of which, by itself, will freely conduct the current in any direct refuses to allow conduction in one direction. Consider first the condition of p-type and n-type germanium just prior to joining fig. 1. The majority and minority carriers are in constant motion. The minority carriers are thermally produced and they exist only for short time after which they recombine and neutralize each other. In the mean time, other minority carriers have been produced and this process goes on and on. The number of these electron hole pair that exist at any one time depends upon the temperature. The number of majority carriers is however, fixed depending on the number of impurity atoms available. While the electrons and holes are in motion but the atoms are fixed in place and do not move.

Fig.1

As soon as, the junction is formed, the following processes are initiated fig. 2.

Fig.2

Holes from the p-side diffuse into n-side where they recombine with free electrons. Free electrons from n-side diffuse into p-side where they recombine with free holes. The diffusion of electrons and holes is due to the fact that large no of electrons are concentrated in one area and large no of holes are concentrated in another area. When these electrons and holes begin to diffuse across the junction then they collide each other and negative charge in the electrons cancels the positive charge of the hole and both will lose their charges. The diffusion of holes and electrons is an electric current referred to as a recombination current. The recombination process decay exponentially with both time and distance from the junction. Thus most of the recombination occurs just after the junction is made and very near to junction. A measure of the rate of recombination is the lifetime defined as the time required for the density of carriers to decrease to 37% to the original concentration

The impurity atoms are fixed in their individual places. The atoms itself is a part of the crystal and so cannot move. When the electrons and hole meet, their individual charge is cancelled and this leaves the originating impurity atoms with a net charge, the atom that produced the electron now lack an electronic and so becomes charged positively, whereas the atoms that produced the hole now lacks a positive charge and becomes negative.

The electrically charged atoms are called ions since they are no longer neutral. These ions produce an electric field as shown in fig. 3. After several collisions occur, the electric field is great enough to repel rest of the majority carriers away of the junction. For example, an electron trying to diffuse from n to p side is repelled by the negative charge of the p-side. Thus diffusion process does not continue indefinitely but continues as long as the field is developed.

Fig.3

This region is produced immediately surrounding the junction that has no majority carriers. The majority carriers have been repelled away from the junction and junction is depleted from carriers. The junction is known as the barrier region or depletion region. The electric field represents a potential difference across the junction also called space charge potential or barrier potential . This potential is 0.7v for Si at 25^o celcious and 0.3v for Ge.

The physical width of the depletion region depends on the doping level. If very heavy doping is used, the depletion region is physically thin because diffusion charge need not travel far across the junction before recombination takes place (short life time). If doping is light, then depletion is more wide (long life time).

HART Communication

For many years, the field communication standard for process automation equipment has been a milliamp (mA) analog current signal. The milliamp current signal varies within a range of 4-2OmA in proportion to the process variable being represented. Li typical applications a signal of 4mA will correspond to the lower limit (0%) of the calibrated range and 2OmA will correspond to the upper limit (100%) of the calibrated range. Virtually all installed systems use this international standard for communicating process variable information between process automation equipment.

HART Field Communications Protocol extends this 4- 2OmA standard to enhance communication with smart field instruments. The HART protocol was designed specifically for use with intelligent measurement and control instruments which traditionally communicate using 4-2OmA analog signals. HART preserves the 4- signal and enables two way digital communications to occur without disturbing the integrity of the 4-2OmA signal. Unlike other digital communication technologies, the HART protocol maintains compatibility with existing 4-2OmA systems, and in doing so, provides users with a uniquely backward compatible solution. HART Communication Protocol is well-established as the existing industry standard for digitally enhanced 4- 2OmA field communication.

THE HART PROTOCOL - AN OVERVIEW

HART is an acronym for "Highway Addressable Remote Transducer". The HART protocol makes use of the Bell 202 Frequency Shift Keying (FSK) standard to superimpose digital communication signals at a low level on top of the 4-2OmA. This enables two-way field communication to take place and makes it possible for additional information beyond just the normal process variable to be communicated to/from a smart field instrument. The HART protocol communicates at 1200 bps without interrupting the 4-2OmA signal and allows a host application (master) to get two or more digital updates per second from a field device. As the digital FSK signal is phase continuous, there is no interference with the 4- 2OrnA signal.

HART is a master/slave protocol which means that a field (slave) device only speaks when spoken to by a master. The HART protocol can be used in various modes for communicating information to/from smart field in3truments and central control or monitor systems. HART provides for up to two masters (primary and secondary). This allows secondary masters such as handheld communicators to be used without interfering with communications to/from the primary master, i.e. control/monitoring system. The most commonly employed HART communication mode is master/slave communication of digital information simultaneous with transmission of the 4-2OmA signal. The HART protocol permits all digital communication with field devices in either point-to-point or multidrop network configuration. There is an optional "burst" communication mode where single slave device can continuously broadcast a standard HART reply message.

HART COMMUNICATION LAYERS

The HART protocol utilizes the OSI reference model. As is the case for most of the communication systems on the field level, the HART protocol implements only the Layers 1, 2 and 7 of the OSI model. The layers 3 to 6 remain empty since their services are either not required or provided by the application layer 7

IBOC Technology

The engineering world has been working on the development and evaluation of IBOC transmission for some time. The NRSC began evaluation proceedings of general DAB systems in 1995. After the proponents merged into one, Ibiquity was left in the running for potential adoption. In the fall of 2001,the NRSC issued a report on Ibiquity's FM IBOC. This comprehensive report runs 62 pages of engineering material plus 13 appendices. All of the system with its blend-to analog operation as signal levels changes. The application of the FM IBOC has been studied by the NRSC and appears to be understood and accepted by radio engineers.

AM IBOC has recently been studied by an NRSC working group as prelude to its adoption for general broadcast use .Its was presented during the NAB convention in April. The FM report covers eight areas of vital performance concerns to the broadcaster and listener alike .If all of these concerns can be met as successfully by AM IBOC, and the receiver manufactures rally to develop and produce the necessary receiving equipment. The evaluated FM concerns were audio quality, service area, acquisition performance, durability, auxiliary data capacity, and behavior as signal degrades, stereo separation and flexibility.

The FM report paid strong attention to the use of SCA services on FM IBOC. About half of all the operating FM stations employ one or more SCAs for reading for the blind or similar services. Before going to the description of FM IBOC system, it is important to discuss the basic principles of digital radio, and IBOC technology. In the foregoing sections we see the above-mentioned topics

2. BASIC PRINCIPLES OF DIGITAL RADIO

WHAT IS DIGITAL RADIO?

Digital radio is a new method of assembling, broadcasting and receiving communications services using the same digital technology now common in many products and services such as computers, compact discs (CDs) and telecommunications.
Digital radio can:
" Provide for better reception of radio services than current amplitude modulation (AM) and frequency modulation (FM) radio broadcasts;
" Deliver higher quality sound than current AM and FM radio broadcasts to fixed, portable and mobile receivers; and
" Carry ancillary services-in the form of audio, images, data and text-providing
" Program information associated with the station and its audio programs (such as station name, song title, artist's name and record label),
" Other information (e.g. Internet downloads, traffic information, news and weather), and
" Other services (e.g. paging and global satellite positioning).

A fundamental difference between analog and digital broadcasting is that digital technology involves the delivery of digital bit streams that can be used not only for sound broadcasting but all manner of multimedia services.

Adaptive Optics in Ground Based Telescopes

Adaptive optics is a new technology which is being used now a days in ground based telescopes to remove atmospheric tremor and thus provide a clearer and brighter view of stars seen through ground based telescopes. Without using this system, the images obtained through telescopes on earth are seen to be blurred, which is caused by the turbulent mixing of air at different temperatures.

Adaptive optics in effect removes this atmospheric tremor. It brings together the latest in computers, material science, electronic detectors, and digital control in a system that warps and bends a mirror in a telescope to counteract, in real time the atmospheric distortion.

The advance promises to let ground based telescopes reach their fundamental limits of resolution and sensitivity, out performing space based telescopes and ushering in a new era in optical astronomy. Finally, with this technology, it will be possible to see gas-giant type planets in nearby solar systems in our Milky Way galaxy. Although about 100 such planets have been discovered in recent years, all were detected through indirect means, such as the gravitational effects on their parent stars, and none has actually been detected directly.

WHAT IS ADAPTIVE OPTICS ?

Adaptive optics refers to optical systems which adapt to compensate for optical effects introduced by the medium between the object and its image. In theory a telescope's resolving power is directly proportional to the diameter of its primary light gathering lens or mirror. But in practice , images from large telescopes are blurred to a resolution no better than would be seen through a 20 cm aperture with no atmospheric blurring. At scientifically important infrared wavelengths, atmospheric turbulence degrades resolution by at least a factor of 10.

Space telescopes avoid problems with the atmosphere, but they are enormously expensive and the limit on aperture size of telescopes is quite restrictive. The Hubble Space telescope, the world's largest telescope in orbit , has an aperture of only 2.4 metres, while terrestrial telescopes can have a diameter four times that size.

In order to avoid atmospheric aberration, one can turn to larger telescopes on the ground, which have been equipped with ADAPTIVE OPTICS system. With this setup, the image quality that can be recovered is close to that the telescope would deliver if it were in space. Images obtained from the adaptive optics system on the 6.5 m diameter telescope, called the MMT telescope illustrate the impact.

A 64 Point Fourier Transform Chip

Fourth generation wireless and mobile system are currently the focus of research and development. Broadband wireless system based on orthogonal frequency division multiplexing will allow packet based high data rate communication suitable for video transmission and mobile internet application. Considering this fact we proposed a data path architecture using dedicated hardwire for the baseband processor. The most computationally intensive part of such a high data rate system are the 64-point inverse FFT in the transmit direction and the viterbi decoder in the receiver direction. Accordingly an appropriate design methodology for constructing them has to be chosen a) how much silicon area is needed b) how easily the particular architecture can be made flat for implementation in VLSI c) in actual implementation how many wire crossings and how many long wires carrying signals to remote parts of the design are necessary d) how small the power consumption can be .This paper describes a novel 64-point FFT/IFFT processor which has been developed as part of a large research project to develop a single chip wireless modem.

ALGORITHM FORMULATION

The discrete fourier transformation A(r) of a complex data sequence B(k) of length N
where r, k ={0,1……, N-1} can be described as


Where WN = e-2?j/N . Let us consider that N=MT , ? = s+ Tt and k=l+Mm,where s,l ? {0,1…..7} and m, t ? {0,1,….T-1}. Applying these values in first equation and we get


This shows that it is possible to realize the FFT of length N by first decomposing it to one M and one T-point FFT where N = MT, and combinig them. But this results in in a two dimensional instead of one dimensional structure of FFT. We can formulate 64-point by considering M =T = 8

This shows that it is possible to express the 64-point FFT in terms of a two dimensional structure of 8-point FFTs plus 64 complex inter-dimensional constant multiplications. At first, appropriate data samples undergo an 8-point FFT computation. However, the number of non-trivial multiplications required for each set of 8-point FFT gets multiplied with 1. Eight such computations are needed to generate a full set of 64 intermediate data, which once again undergo a second 8-point FFT operation . Like first 8-point FFT for second 8-point again such computions are required. Proper reshuffling of the data coming out from the second 8-point FFT generates the final output of the 64-point FFT .

Fig. Signal flow graph of an 8-point DIT FFT.

For realization of 8-point FFT using the conventional DIT does not need to use any multiplication operation.

The constants to be multiplied for the first two columns of the 8-point FFT structure are either 1 or j . In the third column, the multiplications of the constants are actually addition/subtraction operation followed multiplication of 1/?2 which can be easily realized by using only a hardwired shift-and-add operation. Thus an 8-point FFT can be carried out without using any true digital multiplier and thus provide a way to realize a low- power 64-point FFT at reduced hardware cost. Since a basic 8-point FFT does not need a true multiplier. On the other hand, the number of non-trivial complex multiplications for the conventional 64-point radix-2 DIT FFT is 66. Thus the present approach results in a reduction of about 26% for complex multiplication compared to that required in the conventional radix-2 64-point FFT. This reduction of arithmetic complexity furthur enhances the scope for realizing a low-power 64-point FFT processor. However, the arithmetic complexity of the proposed scheme is almost the same to that of radix-4 FFT algorithm since the radix-4 64-point FFT algorithm needs 52 non-trivial complex multiplications.

Chip Morphing

1.1. The Energy Performance Tradeoff

Engineering is a study of tradeoffs. In computer engineering the tradeoff has traditionally been between performance, measured in instructions per second, and price. Because of fabrication technology, price is closely related to chip size and transistor count. With the emergence of embedded systems, a new tradeoff has become the focus of design. This new tradeoff is between performance and power or energy consumption. The computational requirements of early embedded systems were generally more modest, and so the performance-power tradeoff tended to be weighted towards power. "High performance" and "energy efficient" were generally opposing concepts.

However, new classes of embedded applications are emerging which not only have significant energy constraints, but also require considerable computational resources. Devices such as space rovers, cell phones, automotive control systems, and portable consumer electronics all require or can benefit from high-performance processors. The future generations of such devices should continue this trend.

Processors for these devices must be able to deliver high performance with low energy dissipation. Additionally, these devices evidence large fluctuations in their performance requirements. Often a device will have very low performance demands for the bulk of its operation, but will experience periodic or asynchronous "spikes" when high-performance is needed to meet a deadline or handle some interrupt event. These devices not only require a fundamental improvement in the performance power tradeoff, but also necessitate a processor which can dynamically adjust its performance and power characteristics to provide the tradeoff which best fits the system requirements at that time.

1.2. Fast, Powerful but Cheap, and Lots of Control

These motivations point to three major objectives for a power conscious embedded processor. Such a processor must be capable of high performance, must consume low amounts of power, and must be able to adapt to changing performance and power requirements at runtime.

The objective of this seminar is to define a micro-architecture which can exhibit low power consumption without sacrificing high performance. This will require a fundamental shift to the power-performance curve presented by traditional microprocessors. Additionally, the processor design must be flexible and reconfigurable at run-time so that it may present a series of configurations corresponding to different tradeoffs between performance and power consumption.

1.3. MORPH

These objectives and motivations were identified during the MORPH project, a part of the Power Aware Computing / Communication (PACC) initiative. In addition to exploring several mechanisms to fundamentally improve performance, the MORPH project brought forth the idea of "gear shifting" as an analogy for run-time reconfiguration. Realizing that real world applications vary their performance requirements dramatically over time, a major goal of the project was to design microarchitectures which could adjust to provide the minimal required performance at the lowest energy cost. The MORPH project explored a number of microarchitectural techniques to achieve this goal, such as morphable cache hierarchies and exploiting bit-slice inactivity. One technique, multi-cluster architectures, is the direct predecessor of this work. In addition to microarchitectural changes, MORPH also conducted a survey of realistic embedded applications which may be power constrained. Also, design implications of a power aware runtime system were explored.

How to study electronics

Education and training

Electronics engineers typically possess an academic degree with a major in electronic engineering. The length of study for such a degree is usually three or four years and the completed degree may be designated as a Bachelor of Engineering, Bachelor of Science, Bachelor of Applied Science, or Bachelor of Technology depending upon the university. Many UK universities also offer Master of Engineering (MEng) degrees at undergraduate level.

The degree generally includes units covering physics, chemistry, mathematics, project management and specific topics in electrical engineering. Initially such topics cover most, if not all, of the subfields of electronic engineering. Students then choose to specialize in one or more subfields towards the end of the degree.

Some electronics engineers also choose to pursue a postgraduate degree such as a Master of Science (MSc), Doctor of Philosophy in Engineering (PhD), or an Engineering Doctorate (EngD). The Master degree is being introduced in some European and American Universities as a first degree and the differentiation of an engineer with graduate and postgraduate studies is often difficult. In these cases, experience is taken into account. The Master's degree may consist of either research, coursework or a mixture of the two. The Doctor of Philosophy consists of a significant research component and is often viewed as the entry point to academia.

In most countries, a Bachelor's degree in engineering represents the first step towards certification and the degree program itself is certified by a professional body. After completing a certified degree program the engineer must satisfy a range of requirements (including work experience requirements) before being certified. Once certified the engineer is designated the title of Professional Engineer (in the United States, Canada and South Africa), Chartered Engineer or Incorporated Engineer (in the United Kingdom, Ireland, India and Zimbabwe), Chartered Professional Engineer (in Australia) or European Engineer (in much of the European Union).

Fundamental to the discipline are the sciences of physics and mathematics as these help to obtain both a qualitative and quantitative description of how such systems will work. Today most engineering work involves the use of computers and it is commonplace to use computer-aided design programs when designing electronic systems. Although most electronic engineers will understand basic circuit theory, the theories employed by engineers generally depend upon the work they do. For example, quantum mechanics and solid state physics might be relevant to an engineer working on VLSI but are largely irrelevant to engineers working with macroscopic electrical systems.

Early electronics

In 1893, Nikola Tesla made the first public demonstration of radio communication. Addressing the Franklin Institute in Philadelphia and the National Electric Light Association, he described and demonstrated in detail the principles of radio communication.^[13] In 1896, Guglielmo Marconi went on to develop a practical and widely used radio system.^[14][15][16] In 1904, John Ambrose Fleming, the first professor of electrical Engineering at University College London, invented the first radio tube, the diode. One year later, in 1906, Robert von Lieben and Lee De Forest independently developed the amplifier tube, called the triode.

Electronics is often considered to have begun when Lee De Forest invented the vacuum tube in 1907. Within 10 years, his device was used in radio transmitters and receivers as well as systems for long distance telephone calls. In 1912, Edwin H. Armstrong invented the regenerative feedback amplifier and oscillator; he also invented the superheterodyne radio receiver and could be considered the father of modern radio.^[17] Vacuum tubes remained the preferred amplifying device for 40 years, until researchers working for William Shockley at Bell Labs invented the transistor in 1947. In the following years, transistors made small portable radios, or transistor radios, possible as well as allowing more powerful mainframe computers to be built. Transistors were smaller and required lower voltages than vacuum tubes to work. In the interwar years the subject of electronics was dominated by the worldwide interest in radio and to some extent telephone and telegraph communications. The terms 'wireless' and 'radio' were then used to refer to anything electronic. There were indeed few non-military applications of electronics beyond radio at that time until the advent of television. The subject was not even offered as a separate university degree subject until about 1960.^[18]

Prior to World War II, the subject was commonly known as 'radio engineering' and basically was restricted to aspects of communications and RADAR, commercial radio and early television. At this time, study of radio engineering at universities could only be undertaken as part of a physics degree. Later, in post war years, as consumer devices began to be developed, the field broadened to include modern TV, audio systems, Hi-Fi and latterly computers and microprocessors. In the mid to late 1950s, the term radio engineering gradually gave way to the name electronic engineering, which then became a stand alone university degree subject, usually taught alongside electrical engineering with which it had become associated due to some similarities.

Before the invention of the integrated circuit in 1959, electronic circuits were constructed from discrete components that could be manipulated by hand. These non-integrated circuits consumed much space and power, were prone to failure and were limited in speed although they are still common in simple applications. By contrast, integrated circuits packed a large number — often millions — of tiny electrical components, mainly transistors, into a small chip around the size of a coin.^[19]

Basic knowledge
of Electronic parts



I will explain the components to use for the electronic circuits on these pages.

Resistors	Coils
Capacitors	Printed Wiring Boards
Diodes	Relays
Transistors	Wiring materials
Integrated Circuits

Integrated Circuits

An integrated circuit contains transistors, capacitors, resistors and other parts packed in high density on one chip.
Although the function is similar to a circuit made with separate components, the internal structure of the components are different in an integrated circuit.
The transistors, resistors, and capacitors are formed very small, and in high density on a foundation of silicon. They are formed by a variation of printing technology.
There are many kind of ICs, including special use ICs.


The top left device in the photograph is an SN7400. It contains 4 separate "2 input NAND" circuits. There are 7 pins on each side, 14 pins total.
ICs in this form are called Dual In line Package (DIP).
When an IC has only one row of pins, it os called a Single In line Package (SIP).
The number of pins changes depending on the function of IC.

At the bottom left is an IC socket for use with 14 pin DIP ICs.
ICs can be attached directly to the printed circuit board with solder, but it's better to use an IC socket, because you can easily exchange it should the IC fail.

On the top right is an LM386N audio amplifier. It can be used for amplification of low frequency, low power signals. IT has 8 pins and the maximum output is 660mW.

On the bottom right is a TA7368P, which also is for amplification of low frequency electric power. It has a maximum output of 1.1 watts.
It is a 9 pin SIP IC.

---

Common ICs

Below, the most common ICs are shown. (Those parts that I use most.)
For extensive details on each part, see the corresponding data sheet.
The part numbers of the SN74 series ICs are written with a 74, often followed by LS or HC.
LS (Low power Shottky) indicates low power consumption. HC indicates the device is High speed C-MOS (Complementary-Metal Oxide Semiconductor), and is also a low power consumption IC.
The average current consumption for each type of chip is listed below.
The current shown is for when the device is in a LOW state output. In the case of the LOW state output, current consumption is much greater than in the HIGH state output.

SN7400	-----	22mA
SN74LS00	-----	4.4mA
SN74HC00	-----	0.02mA

Several kinds of ICs are not available in the LS or HC type. For example, SN7445 is not available in LS or HC. It is available only as SN7445, the normal type.

Name	Function	Vcc	Pin Assign(Top View)	Remarks
SN74HC00	Quad 2 Input NAND	+5V		2 input NAND circuits entered 4 pieces
SN74HC04	Hex Inverters	+5V		Inverter circuit entered 6 pieces Details
SN74LS42	BCD to DECIMAL Decoder	+5V		One of output takes LOW state serected by the binary input.
SN7445	O.C. BDC to DECIMAL Decoder/Driver	+5V		Open collector type of 7442 Max current of output is 80mA.
SN74LS47	BCD to Segment Decoder/Driver	+5V		Front View Driving IC of ‚Vsegments LED. Open collector type Max resistance voltage:15V 6 and 9 disply type: Related 74247
SN74HC73	Dual JK-FFs With Clear	+5V		2 pieces of JK-FF
SN74LS90	Decade Counter	+5V		Asynchronous 2 + 5 counter. Async preset : 9 Async clear Related 74290 74390
SN74HC93	4-Bit Binary Counter	+5V		Asynchronous 2 + 8 counter.
SN74HC123	Dual Retriggaerable Single Shot	+5V		Single shot resister holds the output in the required time from the input states goes to ON. The output holding time corresponds to C(capacitor) and R(resistor) connected to the Cext(External capacitor) and Rext(External resistor) respectivly.
SN74LS247	BCD to Segment Decoder/Driver	+5V		Front View 6 and 9 disply type: Related 7447
SN74LS290	Decade Counter	+5V		This type is the same as the SN7490, with a different layout of pins. Related 7490 74390
SN74HC390	Dual Decade Counters	+5V		Type that inserted 2 SN7490. Presetting 9 is omitted . Related 7490 74290
4040B	12Bit Binary Counter (CMOS)	+5V		12-stage Binary counter. It has a clear function. Counts downward with an external clock pulse.
4541B	Progarammable Oscillator/Timer (CMOS)	+5V		Programmable 16 stage binary counter. Used in RC oscillation circuits, power reset, output control circuits. Tap outputs of 8, 10, 13, 16 bits are possible by the control terminal.
NE555	Timer	+4.5 to +16V		Max frequency: 500kHz Temperature drift: 0.005%/°C. Max output current: 200mA. Delay time setting :several micro sec to several hours
LM386N-1	Low frequency electric power amplifier	+4 to 12V		Max output: 660mW Load: 8 to 32-ohm Waiting current: 4mA
LM386N-4	Low frequency electric power amplifier	+5 to 18V		Max output: 1.25W Load: 8 to 32-ohm Waiting current: 4mA
TA7368P	Low frequency electric power amplifier	+2 to +10V		Max output: 1.1W Load: 4 to 16-ohm
uPC319	Voltage comparator	5 to 18V ±5 to ±18V		Standard general use comparator with single power supply/dual power supply operation Other compatible ICs LM319 NJM319 AN1319
7975	Multi-melody IC (CMOS)	+1.5 to +3V		Melody IC that includes 8 pre-programmed melodies. It has 2 sound resources and a settable envelope. Title Green-Sleeves Fur Elise Heavenly Creatures Ich bin ein musikante Valse Favorite Holderia Amaryllis Home On The Range

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Three Terminal Voltage Regulator

It is very easy to get stabilized voltage for ICs by using a three terminal voltage regulator.
The power supply voltage for a car is +12V - +14V. At this voltage, some ICs can not operate directly except for the car component ICs. In this case, a three terminal voltage regulator is necessary to get the required voltage.
The three terminal voltage regulator outputs stabilized voltage at a lower level than the higher input voltage. A voltage regulator cannot put out higher voltage than the input voltage. They are similar in appearance to a transistor.

On the left in the photograph is a 78L05. The size and form is similar to a 2SC1815 transistor.
The output voltage is +5V, and the maximum output current is about 100mA.
The maximum input voltage is +35V. (Differs by manufacturer.)

On the right is a 7805. The output voltage is +5V, and maximum output current is 500mA to 1A. (It depends on the heat sink used)
The maximum input voltage is also +35V.

There are many types with different output voltages.
5V, 6V, 7V, 8V, 9V, 10V, 12V, 15V, 18V

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Component Lead of Three Terminal Voltage Regulator

Because the component leads differ between kinds of regulators,
you need to confirm the leads with a datasheet, etc.

Example of 78L05
Part number is printed on the flat face of the regulator, and indicates the front.

Right side : Input
Center : Ground
Left side : Output

Example of 7805
Part number is printed on the flat face of the regulator, and indicates the front.

Right side : Output
Center : Ground
Left side : Input

Opposite from 78L05.