The term TFET stands for tunneling field effect transistor, that has been developed in the year 1992 by T. Baba, as one of the capable changes to the conventional MOSFET’s based on numerous performance factors includes Possible for above the 60mV/decade, sub threshold swing, ultra-low power & ultra-low voltage, the effects of short channel, leakage current reduction, speed requirement exceeding due to the effects of tunneling, capability to work on sub-threshold and super-threshold voltage, similarity in the assembly process as equated with a MOSFET. Taking into attention the above factors, the MOSFET could be changed by a potential substitute in terms of tunneling field effect transistor for the purpose of high-speed, energy efficient , and ultra-low power applications in the area of integrated circuits.
Thermal imaging device is a benefit to the armed forces like navy, army and air force because of its 24 hours working capability to perform well in all climate conditions. Thermal detectors capture the IR(Infrared) radiation produced by all objects above complete zero temperature. The temperature differences of the captured section are denoted as a hectogram. With the beginning of IR detector technology, the large cooled thermal detectors having moving parts and difficult cryogenic temperatures have changed into small, and less expensive uncooled microbolometers having no moving parts. Thermal imaging system due to its numerous advantages has various applications in the military and also defines.
It is widely used by the armed forces for border surveillance and law implementation. It is also used in ship accident avoidance and control systems. In the aviation industry, it seriously mitigates the dangers of flying in the night conditions. They are widely used in military flight to recognize, find and aim the enemy forces. Recently, they are also being merged in civil aviation for health checking of aircraft.
The Bluetooth technology was implemented in the year 1994 by Jaap Haartsen and Sven Mattison. They were working in a mobile company called “Ericsson” which is located in Sweden. After this, five corporations came forward and combined to form the Bluetooth special interest group. Then they implemented the Bluetooth protocol design version 1.0 in the year 1999. It permitted to progress applications and communicating services over the interoperable radio modules and also data communication protocols. It was intended to give the information on the conditions, competencies and their architectures, a number of usage modules were recognized by the Bluetooth SIG.
What is a Bluetooth Device?
A Bluetooth is a high-speed, low powered wireless device that is intended to connect mobile phones or any other movable equipment together. It is an IEEE 802.15.1 specification for the use of low-power radio communications to connect various network devices, namely computers, mobile phones and also other network devices over small distances without using wires. The transmission of wireless signals can be done typically up to 10meters with Bluetooth over small distances.
It is attained by low-cost embedded transceivers into the devices. It supports on the 2.45GHz frequency band and can support up to 721KBps along with 3-voice channels. This frequency band has been fixed aside by international contract for the use of scientific, industrial, medical devices (ISM) and rd-compatible with 1.0 devices.Simultaneously, Bluetooth device can connect up to eight devices and each device gives a unique 48-bit address from the IEEE 802 standard with the point to point connections or multipoint which are being made.
How to Connect a Bluetooth with Other Devices
The following steps involve to knowing how to connect a Bluetooth with other devices
Turn Bluetooth ON/OFF
- Open the device’s settings
- Tap Bluetooth and ON/OFF the switch
- At the top of the mobile screen, a Bluetooth symbol shows when Bluetooth is switched ON
Note: To conserve battery, switch off Bluetooth option when you’re not using it.
Connect Bluetooth Device
To pair with a Bluetooth device, first switch ON your gadget’s Bluetooth. Before you can pair your device with any other Bluetooth enabled gadget, you must connect them. After you have connected the devices, in the future, you can automatically connect the devices when they are in the range of one another.
Unpair, or Change a Bluetooth Device Name
- If your Bluetooth devices have several connections, you can choose which connection to use.
- Your Bluetooth enabled gadget has a Bluetooth name that new devices see when you pair them via Bluetooth. You can change your Bluetooth device’s name.
- Open your Bluetooth enabled gadgets Settings
- Tap Bluetooth and Make sure Bluetooth is turned on.
- Next, to the connected device, you’d like to change, tap Settings
- On the mobile screen that opens, you can change the name of the device and pick profiles, or forget the device.
- Tap Rename the Bluetooth enabled device
- Enter a new name for your device and Tap Rename.
Why Bluetooth Connecting Fail
Bluetooth device mainly depends on both software and hardware to function properly. So if your gadgets can’t speak a common Bluetooth language, they won’t be able to pair.
In general, these devices support the standard Bluetooth 4.2, declared last year, should still be able to connect with devices using, say, the early Bluetooth 2.1, launched back in the year 2007.
The exceptions are devices that use a low energy version named Bluetooth Smart, which works on a variety protocol than older. Bluetooth enabled devices are not backward compatible and won’t pair with older devices that support Classic Bluetooth.
Bluetooth enabled devices that commonly use Bluetooth Smart comprise personal health gadgets like heart rate monitors, fitness bands, etc. These devices will only connect with a smartphone that also uses Bluetooth Smart or Bluetooth Smart Ready.
The devices also available with particular Bluetooth profiles. If Bluetooth is the mutual language for connecting devices, you can think of a profile as a dialect connected with a certain use. For example, you probably aren’t going to be capable of connecting a camera and a mouse because a camera doesn’t support the Human Interface Device Profile. But if both a mobile and a wireless headset support the Hands-Free Profile, you should be able to connect them.
However, if the connecting failure is a matter of consumer error, there are some steps you can fix Bluetooth pairing problems
- Make sure Bluetooth is Activated or Not
- Switch to Discoverable Mode.
- Delete a paired device from a phone and search for it
- Make sure the pairing devices are in near enough closeness to one another.
- Decide which combining process your device employs
- Charge up both pairing devices
- Stay away from the WiFi router
- Update the firmware of the hardware
- Power down likely interferes
- Get away from a 3.0 USB port
Advantages of Bluetooth Technology
- It eliminates radio interference problem by using a technique, namely “Speed Frequency Hopping”. This method employs 79-channels of the specific frequency band, with every device, retrieving the channel for only 625 microseconds, i.e. the Bluetooth device must toggle between transmitting & receiving data from one time period to another. This indicates the transmitters change frequencies 1,600 times every second, meaning that additional devices can make full use of an incomplete slice of the radio spectrum. This ensures that the interference won’t take place as each transmitter (TX) will be on different frequencies.
- The power consumption of the chip (consisting of the transceiver) is low, at about 0.3mW, which makes it possible for least use of battery life.
It assurances security at the bit level. The verification is controlled using a 128bit key.
It is possible to use a Bluetooth device for both transferring and verbal communication as this device can support data channels of up to 3 comparable voice channels.
It disables the limits of the line of sight and one-to-one communication as in another mode of wireless communications such as infrared.
Applications of Bluetooth
The applications of Bluetooth device include the following
- Cordless Desktop
- Ultimate headset
- Automatic synchronization
- Multimedia Transfer
This article gives the information about how to connect a Bluetooth with other devices, and applications. We hope that the above information given in this article is helpful in providing some good insights and understanding of the project. Furthermore, if you have any queries regarding this article or to implement Bluetooth based projects, you can comment in the below section. Here is a question for you – What are the different versions of Bluetooth?
In this article, let us discuss the circuit for recharging the Lead Acid battery using the Solar panel. The concept of solar is not new for us. As day by day, non-renewable energy sources are reducing, and the usage of solar energy is improved. This energy is not only used on the Globe, but also used in space stations where no electrical power is accessible. Here is the simple circuit to charge a rechargeable Lead-acid battery (12V, 1.3Ah) from the solar panel. This solar charger has regulation of current, voltage and also has over-voltage cut off services. This circuit may also be used to charge the Lead-acid battery at constant voltage because o/p voltage is variable.
The transformer is a static device that changes electrical energy from one circuit to another circuit with the help of mutual induction (without any connection) between two windings namely primary winding and secondary winding. It changes power from one circuit to another circuit without altering its frequency, but may be on changing voltage level. This is the simple definition of transformer. This article discusses what is transformer, basic theory and why this only works with AC.
Generally, we all known about shift register, combinational circuits and the other important element in the digital electronics is a counter. The counter circuits are used for counting purposes, and it is also used for measuring the frequency and time. The counter circuits are designed especially for synchronous sequential circuits. The state of the counter is equal to the count held in the circuit by the flip flops. The counters will calculate the number that how many times an event occurred. The counters are the crucial hardware components and they are also known as timers and these are the best examples of the flip flops. These are also used to design programmable timers.
What is a Counter Circuit?
Generally, the counter circuits are constructed by using a number of flip-flops which are connected in cascade. The manufacturing of counter circuits is separate integrated circuits and it is inbuilt in the part of larger integrated circuits. The counter circuits are widely used in the digital circuits. There are different types of counter circuits like synchronous counters, asynchronous counters, decade counters, ring counters, and Johnson counters.
Pin Configuration of AVR Atmega8 Microcontroller
The AVR Atmega8 Microcontroller consists of 28 pins and all the pins of the microcontroller will support two signals except 5 pins. From the 28-pins of microcontroller the port B pins are 9,10,14,15,16,17,18,19, the port C pins are 23,24,25,26,27,28, &1, and the port D pins are 2,3,4,5,6,11,12. The following image shows the pin configuration of the AVR Atmega8 microcontroller and description of each pin is described below.
Pin-1: RESET pin. If we apply low-level signals for a longer time than the minimum pulse length will produce the RESET pin
Pin-2 & 3: A serial communication in the USART
Pin-4 & 5: An external interrupt. From these two pins, one of the pins is active when an interrupt flag bit of the status register is set and the other pin will be active as long as the intruder condition succeeds.
Pin-9 & 10: An external oscillator pins as well as timer counter oscillators. The crystal oscillator is associated with the two pins directly. The pin-10 is used for lower frequency crystal oscillators or the crystal oscillators.
Pin-19: Used for the SPI-channel as a Master CLK o/p, slave CLK i/p.
Pin-18: A CLK I/P, slave CLK O/P.
Pin-17: Used for the SPI-channel as a Master data o/p, slave data i/p. When it is allowed by the master, it is used as an i/p when it is improved by the slave & bidirectional. This pin can also be utilised as an o/p compare with match o/p, which helps as an external o/p for the timer/counter.
Pin-16: Used as a timer or counter1 comparatively by ranging the PB2-pin as an o/p. It is also used as a slave choice i/p.
Pin-15: Used as an external o/p of the timer or counter compare match A.
Pin-23 to 28 is used as an ADC channel. Pin-27 is used as a serial interface CLK and pin-28 is used as a serial interface data.
Pin-12 &13: Analog Comparator Inputs.
Pin-6 & 11: Timer/counter sources.
Frequency Counter Circuit By Using ATmega16
The following circuit shows frequency counter circuit using the ATmega16 microcontroller. This frequency meter or counter is used to measure the frequency up to 4MHz because we are using an 8MHz clock for the ATmega16 microcontroller. The working operation of this circuit is to count the number of pulses of a signal in one second is simply the frequency counter circuit.
To count the pulses of a signal, we are using the timer1 of the ATmega16 and it will measure the frequency by using the normal mode. When we are starting the count pulses it makes a delay of one second, then we stop the timer and read it in the register which contains the number of pulses. If the timer1 is made an overflow then we are enabling the overflow interrupt of timer1 then we are going to count the number of overflows which are which are made by the timer1. The overflow means the timer1 has made 2^16 count. Therefore, by using the following equation the number of pulses in one second can be calculated.
Frequency = i*2^16 + TCNT1
From the above equation
It is used to calculate the number of overflows in one second. Reading the frequency meter is updated for every second.
Digital Stop Watch Using Atmega8 Microcontroller
The following schematic diagram shows the digital stopwatch using an Atmega8 microcontroller. The operational principle of this circuit is, in the starting stage the stopwatch is in the STOP condition and it is identified by through the blinking display. Generally, the counting stats from 00:00, if we press the START button then the count starts. If the watch is in the running condition then the display will not blink and the display will be on.
It will start counting and the mini seconds are displayed. By pressing the halt key the digital stopwatch is stopped, in the halt state the counting freezes and the display starts blinking. By pressing again START key the digital stopwatch starts from the resume counting. The RESET key is used to reset the clock and the clock starts from 00:00 i.e. 0 minute and 0 Sec.
Applications of Counters
- The counters are used widely in the flip-flops.
- It is used in the cricket stadiums to count the number of people entering & leaving the stadium or room or auditorium.
- The operations of microwave ovens and washing machines are by using the counters
- The counters are used in the digital electronic devices like the digital clock, analogue to digital converts, and digital triangular wave generators.
The information in this article is about simple counter circuits AVR Atmega8 microcontroller. I hope by reading this article you have gained some basic information on the counter circuits. If you have any queries about this article or about the implementation of electrical and electronic projects, please feel free to comment in the below section. Here is the question for you, what is the function of the counter circuit?
Nowadays, smartphones based on Android OS are definitely the most famous gadgets.These mobile phones are inbuilt with different apps and you can find on the internet which exploits inbuilt hardware like Bluetooth, Wi-Fi, to control various devices.The proposed system presents a robot that can be controlled using a running app on an Android-based smartphone. Presented here is Smartphone Operated Robot that can be controlled using an app running on an Android phone. The control commands are sent via Bluetooth and the robot has such features as.
- It can be controlled from Android applications by touch/voice commands
- The speed of the robot can also be measured
- The robot will detect and notify to the phone its distance from the nearer problem
- It will also send information about the direction in which it is moving
Smartphone Operated Robot
Android is an open-source OS (operating system) which means that any maker can use it in their gadgets free of charge. It was constructed to be truly open. For instance, an application can call upon any of the phone’s core functionality like making calls, sending text messages, or using the camera. Android was designed on the open Linux Kernel. Furthermore, it uses a custom virtual machine that was intended to optimize hardware and memory resources in a mobile environment.
Android with Other OS
Android is an open source software, designers can change the OS (operating system) to suit their own needs and phones. This becomes an inexpensive and possible alternative to the manufacturer, as opposed to developing an OS in-house or hiring a software company to do it.
It’s not accessible on all carriers, but this is increasing. The battery is not replaceable which is why all the I Phone users you know have it plugged in all the time as the battery degrades.
Windows Phone is closed-source, which means that it is exclusively developed by the company and sheltered by copyright. The Windows Store is limited as there only a few numbers of apps.
Hardware and Software Requirements
The hardware and software requirements of the Smartphone Operated Robot system include 8051 series Microcontroller, DC motors, Motor Driver IC, Crystal, Resistors, Capacitors, Voltage Regulator, Battery, Robot Body, Bluetooth Module, Keil compiler, Language: Embedded C or Assembly and Android Application.
Android Application Operated Bluetooth
- The Android platform comprises support for the Bluetooth network stack, which lets a device to wireless interchange data with other Bluetooth devices.
- The application framework offers access to the Bluetooth functionality through the Android Bluetooth APIs.
- Super simple & easy way to interface using Bluetooth stack.
- 3.3V Device with standard 5V DC Power source.
- Can also support SPI-Protocol, pins are made available.
- Low cost and Low power consumption.
- It has high-performance wireless transceiver system
- It can be used to interface with PC, Mac or Android phones or tablets.
- Generic Default Visibility at Software side: HC-06 or Linvor
- Default Pairing code is not ‘0000’ but ‘1234’.
- Please use Baud Rate with 8-N-1 connectivity from another device.
- Works with any microcontroller with Serial connectivity.
A microcontroller is a smaller computer, which has on-chip RAM, ROM, I/O ports, etc. The features of this microcontroller include the following.
- Well-matched with MCS®-51 Products
- 8K Bytes of In-System Programmable (ISP) Flash Memory
- Strength: 10,000 Write/Erase Cycles
- Operating Range is 4.0V-5.5V
- Fully Static Operation: 0 Hz-33 MHz
- Internal RAM: 256 x 8-bit
- 32 Programmable I/O Lines
- Three 16-bit Timer/Counters
- 8-Interrupt Sources
- Full Duplex UART Serial Channel
- Interrupt Recovery from Power-down Mode
- Watchdog Timer
- Dual Data Pointer
Motor Driver (L293D)
Motor driver IC L293D is a dual H-bridge integrated circuit (IC). In its common mode of operation, two DC motors can be driven concurrently, both in forward & reverse direction. The motor processes of two motors can be controlled by i/p logic at pins 2, 7, 10 and 15. Input logic 00/11 will stop the equivalent motor. Logic 01 & 10 will rotate it in clockwise and anticlockwise directions respectively. Enable pins 1 & 9 (corresponding to the two motors) must be high for motors to start working. When an enable i/p is high, the related driver gets enabled.
- Wide supply voltage range: 4.5V to 36V
- Separate i/p logic supply
- Internal ESD protection
- Thermal shutdown
- High-Noise-Immunity input
- Functional Substitutions for SGS L293 and SGS L293D
- O/p current 1A/channel (600 mA for L293D)
- Peak o/p current 2 A/channel (1.2 A for L293D)
- o/p clamp diodes for Inductive Transient suppression (L293D)
- A DC motor is an electric device that works on direct current (DC) electricity. In any motor, the process is based on simple electromagnetism.
- A simple two-poles DC electric motor (here red represents a magnet or winding with a “North” polarization, while green represents a magnet or winding with a “South” polarization).
- Every DC motor has six basic parts, namely axle, stator, the rotor (a.k.a., armature), field magnet(s), commutator, and brushes.
The TSOP17 series are reduced receivers for IR remote control systems. PIN diode & preamplifier are assembled on lead frame, the epoxy package is designed as IR filter. The demodulated o/p signal can directly be decoded by a microcontroller. This receiver is the standard IR remote control receiver series, supporting all main transmission codes
- Photodetector & preamplifier in one package
- Internal filter for PCM frequency
- Improved protecting against electrical field trouble
- Compatibility of TTL and CMOS
- O/p active low
- Low power consumption
- High protection against ambient light
- Endless data transmission possible up to 2400 bps
- Appropriate burst length is 10 cycles/burst
BC547 (NPN –Transistor)
- The BC547 transistor is an NPN-Epitaxial Si Transistor.
- It is used in general purpose switching & amplification BC847/BC547 series 45V, 100 mA NPN-general purpose transistors.
- The ratio of two currents namely ‘Ic’ and ‘Ib’ is called the DC current gain of the device and is denoted by the symbol of “hfe” or nowadays Beta, (β).
- The current gain from the emitter (E) to the collector terminal (C), Ic/Ie is called Alpha (α), and is a function of the transistor itself.
This Smartphone Operated Robot project is designed to control a robotic vehicle using an android application based device. Bluetooth device is interfaced to the control unit on the robot for detecting the signals transferred by the android application. This data is conveyed to the control unit which transfers the robot as desired. An 8051 series microcontroller is used as a control device.
Remote operation can be done by any android based gadget, upon a Graphical User Interface GUI (GUI) based touch screen operation. Transmitting end uses an android application device remote through which commands are transmitted.
In the Present situation, a Robot is controlled by manual override. Every time a manual action is required to Switch ON and Switch OFF the buttons to control the Robot. So at that time, only Robot is moving according to the manual instruction. Missing the objective that needs to monitor the Robot wirelessly.
Thus, this is all about how to build a Smartphone Operated Robot. We hope that you have got a better understanding of this concept. Furthermore, any doubts regarding this concept or to implement Android application controlled the remote robot. Please, give your feedback by commenting in the comment section below. Here is a question for you, what is the function of TSOP1738?
In the year 1997, the electronic eye security system was found and base of processes in New Delhi. There are different organizations under these systems,such as electronic eye Pvt.Ltd, IIST (Indian institute of science and technology), electronic eye systems, and Mahamahi Exims. The electronic eye security system creates an entire collection of surveillance products and high-tech security. These Systems work on the integration of system and project execution at the customers place for numerous surveillance products.The electronic eye security systems which are available in the market are expensive, and programming is very problematic for a microcontroller based system. Here is a simple and inexpensive electronic eye security system that you can build easily.
Photo-sensing (LM393) based Electronic Eye Security System
The main goal of this project is to design an electronic security system based on a photo-sensing arrangement. It uses a double comparator LM393 that is extensively used in several profitable applications. Here, it is used to detect the input signal through a LDR (light-dependent resistor). The output of the comparator drives a relay and a buzzer. This concept is very beneficial as a burglar warning in public places such as banks, hotels jewelry stores, malls, and homes.
What is LM393?
The LM393 is a dual independent precision voltage comparator accomplished by single or split supply process. These devices are intended to let a common mode range-to-ground level with the only supply operation. Input offset voltage conditions as low as 2.0 mV make this device a superb collection of several applications in buyer automotive and industrial electronics. The features of LM393 include the following.
- Single supply ranges from 2.0 Vdc to 36 Vdc
- Split Supply Range: +/-1.0 Vdc to +/-18 Vdc
- Low Current Drain Independent of Supply Voltage: 0.4 mA
- Low i/p Bias Current is 25 nA
- Low i/p Offset Current: 5.0 nA
- Power Supply Voltage and differential i/p voltage range both are equal
- O/p voltage is compatible with ECL, DTL, MOS, TTL, and CMOS Logic Levels
- ESD locks on the i/ps
- ESD Locks on the i/ps increase the roughness of the device without disturbing performance
Circuit and Working of the Electronic Eye Security System
The circuit diagram of an electronic eye security system using LM393 is shown below. The following circuit is built with various electrical and electronic components like around 12V-0-12V, X1-(750mA secondary transformer), 1N4007 rectifier diodes (D1 through D3), LDR , C1 and C2 filter capacitors, 5V IC17805 voltage regulator, IC2 (dual comparator LM393), 12V PZ- (multi-tone high-gain buzzer), T1 transistor for driving PZ1, T2 transistor BC547 for driving 12V, relay (1C/O) for controlling a bulb (B1), and 10-kilo-ohm potentiometer VR1.
When the light drops on light dependent resistor (LDR1), its resistance extremely falls, which leads to activating an alarm to alert the user.The proposed system is appropriate for locking lockers, cash boxer, etc. This circuit is located in the locker or cash box in such a way that, when the robber opens it and uses a torch light to discover the valuables, light falls on light dependent resistor (LDR1), which performs as an electronic eye.
The signal o/p from the light dependent resistor (LDR1) is fed to IC2. The o/p from IC2 triggers the alarm when light falls on light dependent resistor during a robbery attempt.Similarly, bulb-B1 glows as a visual aware to prevent the burglary attempt.
If the reference voltage at pin-3 of IC2 is less than sensor voltage at pin -2 of IC2, o/p goes low routinely. This specifies that no light is dipping on the light dependent resistor. Low o/p of IC2 is fed to T1&T2. As a result, both are in cutoff state, so no flow of current through the beeper, keeping it in silent mode. Likewise, no flow of current in the relay, and so bulb B1 do not glow.
If the reference voltage at pin-3 of IC2 is superior than sensor voltage at pin-2 of IC2, o/p goes high automatically. This indicates that light is falling on LDR1. High o/p of IC2 is fed to T1 and T2. As a result, both transistors are in on (active) state. The flow of current through the buzzer & relay. The buzzer generates a loud alarm to alert you or people around you and, at the same time, bulb B1 glows as the circuit finishes through relay RL1’s contacts.
Operation of Electronic Eye Security System
- Initially, connect the circuit of the electronic eye security system as shown in the above circuit diagram on the bread board.
- Now connect the battery for the supply voltage of 9v.
- Place the LDR (Light Dependent Resistor) in the light.You can detect no sound is generated from the buzzer.
- Place the light dependent resistor in the dark, then the buzzer starts buzzing. Light emitting diode connected to the buzzer also starts flashing.
- As the light intensity dropping on the LDR growths sound generated by the buzzer increases.
Applications of Electronic Eye Security System
- This system can be used in door bell circuits.
- This can be used in a garage door opening and closing circuits.
- This system can be used in security applications.
Thus, this is all about electronic eye security system using photo-sensing (LM393). We hope that you have got a better understanding of this concept.Furthermore, any doubts regarding this concept or to implement any electrical and electronic projects, please give your valuable suggestions by commenting in the comment section below. Here is a question for you, What is the function of LM393?
The Power MOSFET is a type of MOSFET. The operating principle of power MOSFET is similar to the general MOSFET. The power MOSFETS are very special to handle the high level of powers. It shows the high switching speed and by comparing with the normal MOSFET, the power MOSFET will work better. The power MOSFETs is widely used in the n-channel enhancement mode, p-channel enhancement mode, and in the nature of n-channel depletion mode. Here we have explained about the N-channel power MOSFET. The design of power MOSFET was made by using the CMOS technology and also used for development of manufacturing the integrated circuits in the 1970s.
What is a Power MOSFET?
A power MOSFET is a special type of metal oxide semiconductor field effect transistor. It is specially designed to handle high-level powers. The power MOSFET’s are constructed in a V configuration. Therefore, it is also called as V-MOSFET, VFET. The symbols of N- channel & P- channel power MOSFET are shown in the below figure.
Basic Statures of Power MOSFET
There is three basic status in the power MOSFET which is following.
- On sate resistance
- Breakdown voltage
- Body diode
On State Resistance
If the power MOSFET is in ON sate, then it produces the resistive behavior in-between the drain & source terminals. We can see in the following figure, that the resistance is the sum of many elementary contributions. The RS resistance is the source resistance. It will show all resistance between the source terminals of the package to the channel of the MOSFET.
The Rch resistance is the channel resistance and this resistance is inversely proportional to the channel width & for a given die size, to the channel density. This resistance is very important contributors to the RDSon of the low voltage MOSFET. The intensive work has done to reduce their cell size with respect to increase the channel density.
The access resistance is represented by the Ra. The access resistance shows the resistance of the epitaxial zone directly to the gate electrode. The current direction is changed from the channel to the vertical.
RJFET is the detrimental effect of the cell size reduction. The P implantation is observed from the gate of a parasitic JFET transistor and it has reduced the width of the current flow.
Rn represents the epitaxial layer and it is used for sustaining the blocking voltage. This resistance is directly related to the voltage rating of the device. The high voltage MOSFET requires a thick low dependent layer which is highly resistive and a low voltage transistor requires a thin layer with the higher doping layer which is very less resistive. This is the main factor for the resistance of high voltage MOSFET.
The RD resistance is the equivalent of resistance of the RS for the drain. The RD resistance, represent the transistor substrate and the package connections.
Break Down Voltage
The power MOSFET is equivalent to the PIN diode, if it is in the OFF state and it is initiated by the P+ diffusion, the N- epitaxial layer and the N+ substrate. This structure is reverse biased when it is highly nonsymmetrical structure and the space charge region extends principally to the lightly doped side, which is the N- layers.
Even though, when the MOSFET is in the ON state, there is a no function of the N- layers. Moreover, it is lightly doped rejoin, intrinsic resistivity is non-negligible and it is added to the MOSFET ON- state drain to source resistance.
There are two important parameters to run both the breakdown voltage and the RDSon of the transistor, which is the doping level and the thickness of the N- epitaxial layer. If the layer is thicker, it has low doping level and the breakdown voltage is high. Similarly, thicker the layer, it has the high doping level and the radon is low. Hence we can observe that there is a trade-off in the design of the MOSFET, between the voltage rating and the ON state resistance.
The body diode can be seen in the following figure that the source metallization is connected to both the N+ and P implantations. Even though the basic principle of the MOSFET requires only that the source should be connected to the N+ zone. Thus, this would result in a floating P zone between the N-doped source and drain. It is equivalent to an NPN transistor with a nonconnected base. Under some conditions like high drain current, in the order of the same volts of an on-state drain to source voltage, this parasitic transistor of NPN should be triggered and make the MOSFET uncontrollable.
The connections of the P implantation to the source metallization short the base terminal of the transistor parasitic to its emitter and it prevents the latching. Hence this solution creates a diode between the cathode & anode of the MOSFET and the current blocks in one direction.
For inductive loads, the body diodes utilize the freewheeling diodes in the configuration of H Bridge & half bridge. Generally, these diodes will have a high forward voltage drop, the current is high. They are sufficient in many applications like reducing part count.
Working with Power MOSFET and Characteristics
The construction of the power MOSFET is in V-configurations, as we can see in the following figure. Thus the device is also called as the V-MOSFET or V-FET. The V- the shape of power MOSFET is cut to penetrate from the device surface is almost to the N+ substrate to the N+, P, and N – layers. The N+ layer is the heavily doped layer with a low resistive material and the N- layer is a lightly doped layer with the high resistance region.
Both the horizontal and the V cut surface are covered by the silicon dioxide dielectric layer and the insulated gate metal film is deposited on the SiO2 in the V shape. The source terminal contacts with the both N+ and P- layers through the SiO2 layer. The drain terminal of this device is N+.
The V-MOSFET is an E-mode FET and there is no exists of the channel in between the drain & source till the gate is positive with respect to the source. If we consider the gate is positive with respect to the source, then there is a formation of the N-type channel which is close to the gate and it is in the case of the E-MOSFET. In the case of E-MOSFET, the N-type channel provides the vertical path for the charge carriers. To flow between the drain and source terminals. If the VGS is zero or negative, then there is no channel of presence and the drain current is zero.
The following figures show the drain & transfer characteristics for the enhancement mode of N-channel power MOSFET is similar to the E-MOSFET. If there is an increase in the gate voltage then the channel resistance is reduced, therefore the drain current ID is increased. Hence the drain current ID is controlled by the gate voltage control. So that for a given level of VGS, ID is remaining constant through a wide range of VDS levels.
The channel length of the power MOSFET is in the diffusion process, but in the MOSFET the channel length is in the dimensions of the photographic masks employed in the diffusion process. By controlling the doping density and diffusion time, the channel length will become shorter. The shorter channels will give, the more current densities which will contribute again to larger power dissipation. It also allows a larger transconductance gm to be attained in the V-FET.
In the geometry of power MOSFET, there is an important factor which is the presence of lightly doped, N- epitaxial layer which is close to the N+ substrate. If the VGS is at zero or negative, then the drain is positive with respect to the source and there is a reverse biased between the P- layer & N- layer. At the junction the depletion region penetrates into the N- layer, therefore it punch-through the drain to the source are avoided. Hence, relatively high VDS are applied without any danger of device breakdown.
In the power MOSFET, there is available of P-channel. The characteristics are similar to the N-channel MOSFET. The direction of the current and voltage polarities are in reverse direction.
MOSFET Power Amplifier
There are different types of MOSFET power amplifiers like 300W MOSFET power amplifier, 240W MOSFET power amplifier, 160W MOSFET power amplifier and 100W MOSFET power MOSFET amplifier. But here we are explaining about the 100W MOSFET power amplifier with its circuit.
100W MOSFET Power Amplifier Circuit Operation
The circuit operation of 100w MOSFET amplifier consists of PNP transistor from the differential amplifier circuit. The AC input signal is sent to one of the transistors and the other transistor gets the output signal from the feedback. The AC signal is a coupled to the base terminal of the transistor Q1 with the help of the coupling capacitor and the feedback signal. The feedback signal is fed into the base terminal of the second transistor Q2 with the help of resistor R5 & R6. The potentiometer is used to set the output of the amplifier.
The first stage differential output amplifier is fed to the second stage differential amplifier input. In the case of the first differential amplifier, when the input voltage is more than the feedback voltage than the input voltage of the two transistors Q3 and Q4 of second differential amplifier differs from each other. The current mirror circuit of the transistors is Q5 & Q6. This circuit ensures the flowing of output current in the push-pull amplifier circuit is constant.
Thus, this circuit can be achieved because, when the collector current of transistor Q3 is increased, the collector current of Q4 decreases is to maintain the flow of constant current through the universal point of the emitter terminal of the transistors Q3 &Q4. There is an equal output current in between the current mirror circuit & collector current of the Q3 transistor. The potentiometer R12 protects the applications of DC biasing to each MOSFET because the two MOSFETs are in the balancing to each other.
If the positive voltage is applied to the gate terminal of the Q7 transistor then it will conduct. Correspondingly transistor Q8 will conduct for the negative threshold voltage. To prevent the MOSFET output from the oscillating the gate resistors are used.
Applications of Power MOSFET
The power MOSFET’s are used in the power supplies
- DC to DC converters
- Low voltage motor controllers
- These are widely used in the low voltage switches which are less than the 200V
This article will give the information on the working principle of power MOSFET circuit and its applications. I hope by reading this article you have gained some basic information on the power MOSFET. If you have any queries about this article or to implement electronic projects for engineering students, please feel free to comment in the below section. Here is the question for you, what are the functions of the power MOSFET?
There are different types of projects based on the temperature indicator. Now, here we are explaining about the temperature indicator with the LED display by using a temperature sensor. This project shows the use of a V/F converter monitoring temperature in degree Fahrenheit (F). The benefits of the LED temperature indicator are it can calculate the room temperature, atmospheric temperature, and body temperature. This article discusses the block diagram & circuit diagram of the LED temperature indicator.