Techniques of IC fabrication

Most complex aspect of microelectronic devices is the fabrication of monolithic ICs. There are mainly two types of monolithic fabrication techniques.

1) DIFFUSION METHOD
2) EPITAXIAL METHOD

Here Diffusion method is described below:
DIFFUSION METHOD – To start with the DIFFUSION process highly polished silicon wafer is placed in an oven. The oven contains a concentration impurity made up of impurity atoms which yield the desired electrical characteristics. The impurity atoms are diffused into the wafer under the controlled temperature and the time that the silicon wafer will remain in the oven. This process is called DOPING. When the wafer has been uniformly doped, the fabrication of semiconductor devices may begin. Hundreds of circuits can be fabricated at the same time on the wafer. Important steps to fabricate the IC are performed in the following order: (Let’s take an example of NPN transistor)

1. An oxide coating is thermally grown over the n-type silicon starting material.

2. By applying the photolithographic process, a window is opened through the oxide layer. This is done through the use of masks.

3. The base of the transistor is formed by placing the wafer in a diffusion furnace containing a p- type impurity, such as boron. By controlling the temperature of the oven and the length of time that the wafer is in the oven, you can control the amount of boron diffused through the window (the boron will actually spread slightly beyond the window opening). A new oxide layer is then allowed to form over the area exposed by the window.

4. A new window, using a different mask much smaller than the first, is opened through the new oxide layer.

5. An n-type impurity, such as phosphorous, is diffused through the new window to form the emitter portion of the transistor. Again, the diffused material will spread slightly beyond the window opening. Still another oxide layer is then allowed to form over the window.

6. By means of precision-masking techniques, very small windows (about 0.005 inch in diameter) are opened in both the base and emitter regions of the transistor to provide access for electrical currents.

7. Aluminum is then deposited in these windows and alloyed to form the leads of the transistor or the IC.

Beganto Excels in Engineering Services for the Electronics Industry

Beganto has now launched a wide range of Electronics Engineering Services like Application Engineering, Parametric Search Engine, Component Engineering, Part Builder, Lead Generation, Outsourced Sampling, and Sample Management.

Beganto's electronics engineering services are targeting to change the way the industry has been operating so far. The industry has been struggling to manage various support services related to the industry. These support services not only take much of their time and energy but the focus area of the company is disturbed too. So to help the electronics engineering industry cope with their struggling and low priority areas, but which have huge impact in terms of the overall image of the company, Beganto has introduced its very innovative and cutting edge services. These services put forth the opportunity to the industry players to be one step ahead of their competitors in this globally competitive industry.

These services help engineering companies in:

1. Focusing on the business of Engineering, developing and designing
2. Not paying Engineers for working in support functions
3. Accessing engineering staff any time even occasionally
4. Keeping design engineers focused on their design projects
5. Making your projects and operations much more cost effective

These services help selling, research, and design in parts and very importantly help in improving the ROI of the cost oriented programs like sampling.

More information can be read on http://www.engineeringservices.beganto.com/engineering-services.html

Beganto introduces paid samples on Need-A-Sample

Engineers can now buy samples from distributors using Need-A-Sample, earlier used only to request free samples from suppliers.

Supplementing its breakthrough product Need-A-Sample®, Beganto, Inc. has launched the much awaited tool which allows engineers to buy samples from distributors. The earlier version of the Need-A-Sample facilitated getting free samples from suppliers. This additional capability is based on market research that found that engineers often prefer buying samples. In other cases, free part samples may not be available from suppliers but may be with the distributor for sale. Other than the leading catalog houses, most distributors did not have the tools needed to cost effectively facilitates sample purchases.

This powerful tool for paid samples is available on an integrated platform where users can Search, Source and Track all the samples associated with their projects.

Search
Engineers can use the search functionality to find parts they are looking for. They can select a supplier or search parts across all available suppliers entering a keyword or part number. They can also mention their country of delivery, in stock and RoHS attributes before search. This enables them to have most relevant results for their search.

The search results are articulated in an easy to understand manner and provide the information about the parts that is needed to enable users to decide which parts to order. The results show the name of the suppliers, the distributors from which the searched parts are available, whether these parts are RoHS compliant or not, description of the parts, stock, and price-breaks etc.

Source
At the search results, users can add required parts to the shopping cart by entering the quantity they need. They have the option to buy parts from the distributor or to request free samples for the same part from the supplier. Availability of free samples would depend on the suppliers’ discretion whether they it wants to supply the requested free samples or not.

The free parts are separated and collected in the free samples basket which can be ordered anytime during the session. The ordering process for free samples is not changed.

The users can then use the shopping cart to edit/update the quantity and select the shipping method. Cost of the parts is also displayed accordingly, as calculated. A unique facility of the system is that users are not required to be registered users of the system, though if they are registered (who will obviously have better privileges), can login into the system before giving payment and delivery details. The users can pay using credit or debit cards. A confirmation receipt of the order is provided to the users.

Track
Registered users can track the orders using the Paid Sample Tracker utility of the system while non-registered users can use the Sample Order Status utility. The system allows the users to track the orders in real time.

With the launch of this new tool, Beganto has filled the gap in the sampling activity of the electronics industry. Now the segment of paid samples is not only covered through Need-A-Sample but the possibilities of generating new business opportunities have just gone bigger. This also demonstrates the ongoing efforts made by Beganto to equip the electronics industry with innovative solutions to manage their sampling activity and help generate qualified business leads across all segments. This new tool would not only be useful for distributors and suppliers but is envisioned to be extremely popular among the 45,000+ design engineers registered to use the Need-A-Sample system. Beganto is committed to give engineers a whole new experience equipping them with the easiest way to search, order and track the samples for the electronics parts and a platform which puts the whole supply chain together.

Information about Beganto, Need-A-Sample, and the BeON™ network is available from BEGANTO (www.beganto.com): or by contacting at 1-510-474-1014 (Toll Free) or sales (at) beganto.com. The company is headquartered at 48521 Warm Springs Blvd, Fremont CA 95439.

Charge Pump - To Measure Distance

There are several projects where there is a need to measure distances of any object. Sensors are being used frequently for such type of applications but 3D optical measurement is still quite a difficult task for sensors.

The ability to tell the difference how far an object is from the sensor is very useful for imaging applications, and low cost components like sensors are mainly considered for this purpose. Now charge pump can play a significant role in getting all kind of information related to distance from the sensors.
There are two possible methods which can be used to take the information:

By processing a large amount of data quickly.

By modulated light source synchronized with the sensor.

Now, let’s take a brief idea of measuring a distance of any object with the help of modulated light source. Here the charge pump is a Photonic Charge Pump Mixer, a CMOS type, comprises two p-channel MOS transistors working in counter-phase clocking. A transmitter is also used to generate the light pulses which are focused on an imager. The light travel path causes the phase delay with respect to the source which at last is measured. The distance measured is proportional to the phase shift divided by the modulation frequency.

The bias condition makes the transistors to operate between inversion and accumulation conditions at each gate change. Now the minority charge carriers combines with the majority ones which are attracted from the substrate and convert into charge packets that flows to the source terminal. The important point of this device is that the transistor bias conditions depend on the light intensity and the conditions change when the light impinges on the part of the device. There is an integrator behind the charge pump on which the charge gets accumulated after the bias conditions get changed.

The two integrators are connected to two PMOS one at a left channel and the other at the right channel that work independently and the accumulated charge integrates at different time slots. This when synchronized with the modulated light source, the difference of the two outputs (VOR - VOL) is a measure of the light phase shifting and the distance of the backscattering object.


Author: Gary Jones (Component Engr.)
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MICROCONTROLLER (For some control application)

Microcontroller is ‘single chip computer’ If you try designing a computer systems (For some control application) using a traditional microprocessor like 8086, you can abandon the project in frustration, trouble is that the microprocessor is just one component of the system and you need to add like RAM, ROM, timers, counters and interrupt circuitry and I/O ports to make it complete. This is complex job and requires sophisticated knowledge of processors internals .It’s here microcontroller comes for our rescue.

Microcontrollers with flash memory, which is non volatile memory that can be erased using electrical signals, the basic idea is to write the programs (mostly in assembly language or ‘C’) on PC and convert into machine language code, belonging to the target microcontrollers instruction set. Once this is done, the machine code can be transferred to the non volatile memory of the microcontroller via simple circuit, connected to the serial or parallel port .This process is called the programming or ‘burning the micro’.

One most expensive device which is known as ‘Piggy Back’ version which has no ROM memory internally, instead pin outs on the top of the microcontroller form a socket in which EPROM program memory device can be installed.

APPLICATIONS:-Microcontrollers are frequently used in automatically controlled products and devices as

1 LCD control
2 Motor controls
3 Remote controls
4 Car Audios
5 Disk players
6 Camera /cane coder
7 Video Game console
8 Washing machine
9 Vacuum cleaner
10 Ventilation systems
11 Microbots
12 Fire and security machines

Author: Mark Thompson(Component Engr.)
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DVI (Digital Video Interface Connectors)

DVI was developed by DDWG (Digital Display Working Group) to improve analog and digital image quality in PC applications. There are three types of DVI connectors:

1. DVI-A for Analog signals.
   
2. DVI-D for Digital signals
   
3. DVI-I (Integrated) for both analog and digital signals.

The length of the cable is flexible from 5 to 25 meters. It handles bandwidth about 160MHz.This provides connection between computer and its display devices. This is used with LCD monitor not with old VGA cable. DVI gives better quality compared to the VGA.

Therefore, before buying an LCD, make sure that graphics card has DVI connector and same time also make sure that LCD has it too. Most of the LCD today has both VGA and DVI connector but there may be some which has VGA connector, to save cost.

DVI is digital solution and need no conversion, also faulty VGA cables would result in degradation of quality. Cost is low and high speed way to interconnect peripheral devices.

Applications:

1. Computer Monitors
   
2. Set Top Boxes
   
3. A/V Receivers
   
4. HDTV
   
5. Computer Video Cards
   
6. High-End DVD players
   

Author: Mark Thompson(Component Engr.)
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Voltage Detector and Its Technology

The name itself speaks about the function of Voltage Detector and that is to detect the voltage. In the more explanative way it detects the voltage that goes down below a set value or any change that has occurred between the two voltages.

The detector gives the fast response when it senses the deviation in the instantaneous voltage rather than its average or RMS voltage. It is capable of finding out large error quickly but becomes slower in case of smaller errors. Also, it can detect any kind of change in the voltage monitored, whether it is a positive change or a negative change.

Detector works as a safety tool to alert the user of dangerous voltages. This safety tool is an electrical voltage detector. It detects and warns of potentially hazardous voltage levels on conductors such as power cables and metallic objects. The detector is accomplished through capacitive coupling which charges the capacitive leaf sensor, when brought near a conductor. The charge is converted into a voltage signal that is low passed filtered and notch filtered to eradicate the extraneous and telephone ringing signals. Further, the filtered voltage signal is converted to DC and drives a ten element LED bar graph display to show the appropriate level of voltage of the conductor and the hazardous voltage is indicated by a buzzer alarm. All the workmen must be aware of such dangerous voltages before they start work on the conductors. Now, if the voltage is less than or about 150V RMS, then the voltmeter can be safer to use otherwise it is highly undesirable. For this purpose, the voltage detectors were designed to read the presence of a voltage on a conductor without actually contacting the conductor.

A voltage detector can be compared to another device called Reset which does the same function. A voltage detector indicate a voltage that is above or below a specific value but doesn’t provide any time delays whereas Reset not only detects the voltage but has the facility of delaying the reset signal to allow the voltage to arrive at its nominal value.

A Voltage Detector can be used in various kinds of applications. It is used as a combination with LED flash light to detect the presence of electric field under the influence of which produced a flash when placed against the electric field. In the projects of electrical infrastructure, it helps to detect voltages without coming close to the live wires or other metallic objects with the objective to prevent any kind of injury. For example, cities like New York etc. have a tremendous electrical infrastructure where metallic objects get electrified easily by power lines. Voltage detector is also used to detect stray voltages, a low level of voltage, which animals normally encounter in their daily life.

Stray voltages are produced when the animals comes in contact between the surfaces with a voltage difference and a small electrical current flow through the animal. Stray voltages have a severe effect on the animal’s behavior and even their productivity of milk and livestock.In another application, a specially design AC Voltage Detector by Hotstick USA, can be used to read the presence of exposed and dangerous wires or voltage carrying surfaces by finding out the electrostatic field from a safe distance. For example, a 7500 V distributed line can be detected from 200 feet away. Hence, the market prospect of Voltage Detector is very good in the future due to the increase in demand of this device. The increase in the utility of electronic items by the developed nations like North America and Europe who have started exporting their products to other developing nation like that of Asian countries, increased in the awareness of electronic designs and their related products. Consequently, Voltage Detectors are in high demand and will contribute heavily in the growth of nation’s economy.


Author: Gary Jones (Component Engr.)
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Voltage Regulator an electronic equipments...

Most of the electronic equipments require constant voltage for their circuit operation and for which a device was designed known as Voltage Regulator. It delivers a constant voltage level to a circuit where large variation in the input voltage and load current occurs or where voltage fluctuation difference in supply voltage vary up to large extent. Voltage Regulator is mainly two types.

1. Linear Voltage Regulator: - These are the regulators which are used between a supply and the load. They provide a constant voltage by varying its effective resistance.


2. Switching Voltage Regulator: - Such regulators transform the supply into an alternating current by using a switching element, which is then converted into a different voltage with the help of capacitors, inductors etc. and again converted back to DC.

Now let’s say about the market prospects of voltage regulator. There would be a steady growth in the future for voltage regulator due to the use of more transistors switches specially IGBT and microprocessors. Therefore, a big change in the project applications utilizing electronic designes has increased the demand of Voltage Regulators. There are some African and Middle East countries where the power supply is not appropriate and useful due to its bad quality. Such factors have really enhanced the future prospects of Voltage Regulators.

Moreover, the improvement in the infrastructure of developed nations and exporting their product to developing nations like Asian Pacific countries have increase the awareness on electronic design which showed a positive impact on the overall market of Voltage Regulators. Another important factor is the fluctuation in the power supply which is very less in the developed nations like North America and Europe that is only 5%. But if we compare that with the other developing countries like Asia Pacific and Rest-of-World, for example, it comes in the range of 10 to 20 % and the voltage fluctuation of more than 10% is harmful for any equipment which connected to the power supply.

Author: Bruce Staplez (Component Engr.)

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Liquid Crystal Display (LCD) Solution

LCD contains Liquid crystal solution, separated by two sheets of polarized material. Crystals either allow the light or block the light to pass. LCDs are made up of monochrome pixels. These pixels are sub divided in sub pixels which can be controlled to yield many number of possible colors.

LCD displays mostly are used is followings:

1. Watches
2. Cell phones
3. Televisions
4. Digital televisions
5. Computer Monitors
6. Pocket Calculator

These are of less size, No bulky picture, this application is important where size and weight are important

They require very less power.
They have some limitations as well, as problem with view angle and response time in CRTs.

The man who improved the LCD and kicked off the markets is James Fergason who graduated from Missouri University in 1956 with a degree in Physics and then joined research laboratory where he studied Liquid crystals.

James did not discover how to use LCD .The first commercial use of LCD came in quartz watches and James finally created his own manufacturing company.

The man’ latest invention includes safety eyewear whose liquid crystals became opaque instantly when hit by intense radiation like lasers, thus protecting eyes.

Author: Mark Thompson (Component Engr.)

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BEGANTO’S BeON NETWORK ADDS BLOG TO STIMULATE ENGINEER DIALOGUE

Adding a new dimension to its networking function, Silicon Valley-based tracking solutions provider Beganto is now giving engineers an opportunity for sharing technology insights at http://beganto.blogspot.com/. Ranging in subject matter from LED technology advances to background on Bluetooth, the on-line dialogue supplements Beganto’s basic service to engineers, giving them easy access to product data and evaluation samples (through http://www.needasample.com/) and facilitating management for component suppliers of the resulting new business opportunities.

Beganto expects the new blog to promote (free) membership in BeON™, the Beganto Open Network, which currently links 40,000 engineers with their preferred component sources – manufacturers, plus their authorized distributors and field sales representatives. Beganto’s search and sample service to engineers is the first step in the Beganto closed loop feedback and tracking system, Design Winner™.

Demand creation is the name of the game, according to Beganto CEO Sunil Grover, and Beganto supports demand creation by automating follow-up and closing the loop on all the sample requests NeedaSample® processes, even those from new or unknown prospects that might otherwise get lost in the shuffle. Engineers and buyers get the information, datasheets, samples and quotes they need, from a central source – no need to visit dozens of Web sites or enter the same information repeatedly. Component vendors generate leads, which they can share with their rep and distributor partners; but most important, they get both online and live support, to track their samples to design wins, and even to final manufacturing anywhere in the world.

Supplier members in the Beganto Open Network (BeON™) include such high profile users as ALPS, Catalyst, Fox, Hirose, JAE, JRC, Mueller, NEC, Optek, ROHM, Torex, United Chemi-Con and U.S. A’Syck.

Information about Beganto, NeedaSample, and the BeON™ network is available from BEGANTO (http://www.beganto.com/) or by contacting Sunil Grover, CEO, at 510-687-5101 or sunil.grover @ beganto.com. The company is headquartered at 48521 Warm Springs Blvd, Fremont CA 95439. A complete roster of blog entries can also be accessed at http://digg.com/users/beganto/new/dugg.

ABOUT BEGANTO

Beganto, Inc. (http://www.beganto.com/)) provides the electronics industry a sophisticated web-based information system for selecting, sampling, sourcing, and tracking products through the supply chain. BeON™, the Beganto Open Network, welcomes engineers, buyers, distributors, and manufacturers’ representatives as members at no charge. Component manufacturers become Sponsoring Suppliers through paid use of Design Winner™, which facilitates tracking component opportunities from sampling to the point of design win and through RFQ, P.O. and shipment to the point of manufacture, anywhere in the world. The privately held company has its headquarters in Fremont, California, and an office in India.

BEG7014, NR, Beganto blog

CODEC DEVICES

You must have played mp3 songs or seen movies on your computer using applications like Winamp, Windows Media Player, Real Player, Xing Player, etc. These applications use ‘compressor-decompressor’ software programs, commonly called CODEC. These programs are used to code and decode data or signals from one format to another so that the end devices are able to interpret and play the signals. Media like audiotapes and VHS/Betamax tapes use analog signals to store the files while CODECs are meant to store digital files.

How CODEC works:

CODEC devices, in addition to the appropriate software, also have analog-to-digital and digital-to-analog converters used for audio and video data. They use digital signal processing, filtering, impedance synthesis, filters, etc. to code/encode the data. In video signals, the audio, video and metadata streams are combined or joined together using a video file format. Common video file formats are: mpeg, .mov, .mp3, etc.

Selection:

The basic criteria are:

• Audio CODEC: Used to compresses/decompresses digital audio signals or data with reference to standard audio file format or streaming audio format. Some audio formats are mp3, DTS, WMA, etc.


• Video CODEC: Used to compress digital video. Common formats are: MPEG (part 1, 2, 3, 4), Windows Media Video, Real Video, DivX, etc.


• Loss compression: Some loss in data quality occurs in this type of compression. Common types are mp3, WMV, DTS, etc. Movies use this kind of compression.


• Lossless compression: The original signal quality is retained. This produces higher file sizes. These are used in digital signal processing applications where further data processing will be done.


• Channels: Channels are individual lines of data that make up the signal. The higher the number of channels that the device can accommodate, the better the quality will be (e.g. 4/8/16/ 32 channels).


• Other factors are the type of chip, voltage, etc.

Applications:

CODEC allow you to enjoy digital movies and music. They are also used in VoX systems for filtering and pulse code modulation, analog line termination, encoding of POTS subscriber lines, integrated access devices, SOHO/residential gateways etc.

High Definition Television Using Led and Laser Beams

High definition televisions are in a great demand these days. The new technologies have diverted the focus of viewers from Black and White to Color picture that has far better resolution and picture quality.

Today, these high definition televisions have gone into more sophisticated system. So, the manufacturers have given more attention to the appearance of the picture on the screen using various color schemes. Consequently, the vast change made into this field is the replacement of tubes or bulbs that give off white light that filtered into primary colors and remixed with Lasers and Light Emitting Diodes or LEDs.

The idea to replace these lamps with LEDs or Lasers is to get much better color saturation with an efficient design.

These optical components do not beam white light, but rather its basic three building blocks: red, green and blue. Beams are emitted in narrow beam of wavelengths near to those of single, pure colors, giving off the brilliant, saturated red of a blazing sunset or the glittering, luminous blue of a rainbow. Beam these three primary colors in various intensities at one spot on the television screen, and a palette of hues can be created in a wider range than in TVs without this technology.

The utilization of such components have added to an advantage besides excellent resolution, reduced flickering problem, and improved brightness and color contrast that the LEDs are expected to last the lifetime of TVs than the previous bulbs which require replacement in every few years. Moreover, the cost in manufacturing is also decreased since LEDs are highly inexpensive as compared to the bulbs or tubes.

Author: Gary Jones (Component Engr.)
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Introducing Be-ON: Beganto Electronics Open Network

We are creating an online open network for the electronics industry and would like your opinion on it. Here is some background. The engineers designing electronics equipment need samples or 5-10 pieces of the components needed to go into the equipment. Samples can be purchased off the web of distributor websites or obtained from manufacturer's reps for free. Once samples for the entire board are obtained, the board can be tested and it can be determined if the design was a success. Sounds simple? Its not. A new equipment design could contain 100s of components. The first challenge is to find what the part numbers for these component are. Once you are past that hurdle, these may or mayn't be available through online distributors. Samples may or may not be available either. It becomes a challenge because your design requires 100 components from a total potential possibility of over 25 million components.

That is why we are creating an online network. It is open i.e. there is no cost to join and anyone can join. How are we doing it? By keeping it simple. The first thing that will be available through this online network will be samples. So we are engaging the manufacturers reps representing thousands of lines and inputing their information in the system. An engineer can now come to the Beganto system by accessing www.needasample.com and select the manufacturer for whom he/she wants a sample.

This request gets automatically routed to the manufacturer's rep in his territory who can get him/her that sample. Its that simple!

We think that as more engineers get their samples fulfilled through needasample.com and more reps will be able to generate design wins, component manufacturers would like to get involved too and use this as an online mechanism for sending samples and generating sales leads. As more component makers join, more engineers will join and the network will grow.

That's why this online network is call Be-ON, short for Beganto Electronics Open Network. Its the positive impact that this online program can have on accelerating new product design and innovation that gets us all at Beganto so very excited. So, what turns you ON?

Sunil Grover
co-Founder CEO
Beganto, Inc.

Boost LED Performance Via Current Source

For optimum performance, high brightness LEDs should be driven by a current source rather than by a voltage source. This article examines the design of a constant-current LED driver that can be used for driving a string of series-connected LEDs. The number of series-connected LEDs can vary from one to several. To drive the LEDs, the power-stage topology is a modified buck boost converter.
There are many integrated driver solutions in the industry; one possible integrated driver solution to implement the controller subsystem is using the MAX16818 from Maxim Integrated Products. This is an average current mode controller with a transconductance amplifier for the current error amplifier. The current-sense voltage across the current-sense resistor is amplified internally by a factor of 34.5. The transconductance of the current error amplifier is 550μS and the peak-to-peak saw tooth is 2V. In this circuit, the input current is sensed by a resistor, Rs in the return leg.
The value of the current-sense resistor is set by the average current limit required. The maximum voltage across the LEDs is where n is the number of LEDs and is the maximum voltage drop in the LEDs at the full-load current, if the maximum output power is P max = VLED max * If and the efficiency is η. Thus, the maximum input current is:

I in max = P max/ η x V in max

The minimum value of the average current limit threshold is 24mV. The current-sense resistor value can be calculated as:

Rs ≤ 0.024/ I in max * Ω

To prevent oscillations in the PWM comparator section of the controller, the slope of the signal on the negative input of the comparator should be less than the slope of the saw tooth on the positive input. The slope of the saw tooth is given by Vsfs. while the gain of the current error amplifier is given by

Gca = 34.5 * gm * Rc.

In this equation, gm is the transconductance of the CEA The output of this amplifier goes to the negative input of the pulse-width modulation (PWM) comparator. Positive input of the PWM comparator is the saw tooth that has a peak-to-peak amplitude of Vs with a switching frequency, fs. This is the AC gain of the current-error amplifier from the current-sense voltage across Rs to the output of the amplifier at the high frequencies below the pole from the compensation capacitor, Cp. This is the gain of interest at the PWM comparator section.

INFRARED SENSOR

Infrared (IR) sensors are used in night vision cameras and goggles to detect heat emitted by objects. Since ambient light is absent, radiations emitted by the object are picked up by the sensors and used to form an image of the object. These devices can detect the presence of an intruder and are very important in guarding sensitive infrastructure. They are also used for non-contact temperature measurement.

How it works:
Red color has the longest wavelength and infrared means the wavelengths below this visible red. The IR detecting unit uses a silicon photodiode as the light-detecting source to convert the infrared radiation into an electric current. Since an object like a human body has different temperature zones, the electric current that is produced will also vary and can be used to form a map of temperatures or varying infrared colors from dark red to blue.

Selection:
The following factors are useful in selection:

• Responsivity - the responsivity at different frequency range measured in mV


• Sensitivity is a very crucial factor in infrared sensors and it should be very high and efficient.


• Field of view - the circular range in which the unit can sense radiation


• Stability


• Type of electrode


• Response time is the time taken by the sensor to detect, sense the object and send response.

Applications:

• IR sensors are used to build cameras or radiation detecting units, night vision goggles, and security and monitoring equipment.

• IR sensors find usage in process industries where the temperature can be between –30 deg C to 3000 deg C. Some of the process industries are paper, glass, metals, plastics, cement, chemical, food, petrochemical, textiles, etc.


• They also help firefighters to see smoke and save lives. PDAs and other computers and digital cameras use infrared technology to send and receive data.


• They are also used in motion detection and other equipment.

Author: Ashutosh Saini (Component Engr.)

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Brief about ISDN Line Interface

Integrated services digital network (ISDN) is a type of telephone circuit that allows digital signals of data and voice to be sent using the standard telephone wire. It gives better reproduction of signals and speed of transmission. ISDN line interfaces allow routers and multi-channel port boards to be connected to the ISDN system or the central office. A set of protocols and codecs are defined that allow the encoding of digital voice and data so that they are understood by analog systems.

Types of ISDN line interfaces:

• Basic rate interface (BRI): These are used in TV and radio broadcasting centers and use the MPEG codec. They use up to two 64 kbps channels.
• Primary rate interface (PRI): These are used for PBX connections. They can have up to 23 channels.
• There are two types of channels: B (bearer) type used for data and information transmission and D (delta) channel used for signaling.

Selection parameters for ISDN line interfaces:

• Send/receive separation: To reduce leakage of signals from send and receive paths, extra circuits are attached so that signals from the send path do not mix with those from the receive path.
• Acoustic coupling reduction: In studios, when the speakers use a microphone, an acoustic path is formed between the sent and received paths. By using functions like reducing the dynamic gain and adaptive cancellation, this issue is reduced.
• DAC conversion: 16bit digital to analog converters are used for connecting the analog equipment to the digital.
• Sampling rate conversion: The studio and the ISDN equipment operate at different frequencies. A suitable step-up and down process is needed to get them both in sync.
• Auto gain control: This is used for both the send and receives signals to smooth out the variations and takes care of different types of phone instruments.
• Dynamic equalization: This feature balances the frequencies of different makes of equipment. The processor of three band dynamic equalization is used.
• Caller ducking: the host to ‘kill’ unwanted conversation from other callers.
• Caller ID verification: Allows caller ID information to be transmitted.

Other parameters to be considered are: memory per channel, voltage/current, tempratures, etc.

Applications:

ISDN line interfaces are used to transmit voice and data in studios, PBX, TELCO, radio broadcasting stations, conferencing between remote speakers, etc.

Author: Deepak Raina (Component Engr.)

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Advancement In Visible LEDs Technology

IRC Advance Film Division which is TT Electronics Company has developed company’s Anotherm Aluminum Substrate material which offers superior thermal management for use with LED technology.

IRC’s patented Anotherm substrate provides display system design engineers a lighter, cooler and less expensive method of mounting multiple visible LEDs.

IRC’s Advance Film Division recently developed this economical anodized aluminum substrate material with superior thermal conductivity to address the problem of heat dissipation in direct mounted LEDs and LED arrays.

The Thermally conductive aluminum alloy enables design engineers to mount Visible LEDs and other components directly to it, eliminating the need for attached heat sinks, mounting hardware and associated assembly costs.

Economical solderable thick film conductors can be screen-printed directly to the Anotherm substrate to connect surface mount packaged components. The rugged Anotherm technology can operate in extreme temperatures – up to 400 degrees centigrade.

Author: Sanjay Chawla

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Introduction to Beganto Inc.

Beganto is a rapidly growing Silicon Valley company that has developed patent-pending technology to provide search, sample management and tracking solutions for the electronics industry. Beganto is privately held and profitable with headquarters in Fremont, California and development center in India.

Engineers, planners and buyers from electronics manufacturers (customers) use BeON to search, sample, source and track parts for their projects.

Basic membership in BeON is free for qualified suppliers, reps and distributors, and only requires that participants agree to uphold Beganto's quality of service pledge to the end users.