Parametric Amplifiers ( Term Paper )

Assalam u alaikum !

Today I want to share a term paper I wrote for my final year Microwave Communication Subject ..

I hope it will be easy to understand the Parametric Amplifiers.

ABSTRACT

This article is a brief study of Parametric Amplifiers. It discusses the needs of communication over long distances and the biggest problem of weak signal transmission and its amplification. Its development is overviewed and structural analysis is also provided to enable reader to understand the componential and logical requirements. This article also covers its working step by step and functionality in different required conditions. Its implementation in different fields and areas is outlined so that the reader would know and understand its applications in real world. In the end current and future research is outlined in the article for the reader to enhance and expand the new ideas. In conclusion, this article lets you through its past, development, structure working and future research areas

It has always been a dire need of humans to communicate over long distances for which they have designed many structures and systems. Long distance communication needs the signal to be either very strong, powerful or to be repeated every time they loses their power. For this problem the need of amplification is raised and solutions have to be found for successfully delivering the signal to desired destination.

In the past there had been many amplification techniques such as operational amplifiers and transistors etc. When it comes to communication we need to be as fast as we can. Old amplifiers were unable to deliver completely at very high frequencies due to their structural and logical limits. For the need of high frequency transmission, scientists invented such amplifiers, which were able to fulfill the required needs. Those amplifiers were named as Parametric Amplifiers and are still currently in use.

As the name suggests, parametric amplifiers use the parameters involved in its structure to provide desired amplification. Parametric Amplifier are constructed as shown in fig 1.

It has a very simple structure consisting of two tank circuits one for signal entrance and output each. PUMP here is the basic component which provides amplification by varying itself. As in the figure it maybe a variable capacitor or varactor diode or any other mechanical machinery that could change the capacitance. Signal is fed in the left tank which has a certain frequency (f1) and a load is connected to tank 2 which varies the frequency of tank 2 (f2). Now the Pump is varied accordingly with these two frequencies to provide amplification and its frequency must satisfy the relation.

            f₃ = f₁ + f₂

Where, f₃ being the frequency of the pump. What happens is when the signal with a certain voltage comes through tank 1 and goes through the PUMP, at that instant when the peak of the signal arrives, pump changes its capacitance which enhances its voltage by following relation.

Q = C _* V

The enhanced voltage is definitely more powerful and is able to travel longer distances.

The main advantages of parametric amplifiers over other amplifiers are their high power handling and very less noise and attenuation. Parametric amplifiers are theoretically lossless due to usage of capacitors and inductors and negative resistance.  Transistors and op-amps on the other hand are not efficient to operate on high powers and high frequencies although with the invention of MESFET and HEMT based devices have overcome these problems and have got an upper hand on parametric amplifiers these days.

Parametric amplifiers are used in various applications such as radio astronomy and long range satellite communications. It can be used in frequency conversions from audio to radio frequencies and can also be employed on high frequency channels such as fiber optics. As everything has some Pros and Cons, parametric amplifiers suffer with the problem of tuning. As they work on LC tank oscillators they work on a very narrow bandwidth and signal can be deviated by external noise and other factors. Parametric amplifiers are used with external filtering circuits to overcome this problem.

Parametric amplifier is currently and for future, a very hot topic of research. Currently with the invention of fiber optics parametric oscillators are being employed in optics as well. Optical parametric amplifier is the latest form of such technology, in which a beam of light of frequency ω_s is split into two different beams of lower frequencies ω₁ and ω₂ by using nonlinear optical crystal with the requirement

ω_s = ω₁ + ω₂.

The output beams in optical parametric generation are usually relatively weak and have relatively spread-out direction and frequency. This problem is solved by using optical parametric amplification (OPA), also called difference frequency generation, as a second stage.

In an OPA, the input is two light beams, of frequency ωs and ω1. The OPA will make the ωs beam weaker, and amplify the ω1 beam, and also create a new beam at the frequency ω2 with ωs=ω1+ω2.

These optical parametric amplifiers are now being used and researched in various fields related to optics. Some of which are:

1-      Spectroscopy

2-      Polarization-independent two-pump fiber OPA.

3-      Continuous-Wave Fiber Optical Parametric Amplifier with 60-dB Gain Using a Novel Two-Segment Design

4-      Quantum metrology with parametric amplifier-based photon correlation interferometers

5-      Frequency domain optical parametric amplification.

Although new technologies have been developed for these requirements, parametric amplifiers still offer a vast area for future research and implementation. With development of optical fiber and other related techniques parametric amplifier is globally being researched by various government and private institutions and organizations and has a greater chance of development in future.

       Citations

Electronic Communication Systems. (1999). 4th ed. MC-Graw-Hill Publications.

1-      Howson, D. and Smith, R. (1970). Parametric amplifiers. 1st ed. London: McGraw-Hill.

2-      Kravtsov, Y. and Osipov, G. (1967). PARAMETRIC AMPLIFIER. 1st ed. Ft. Belvoir: Defense Technical Information Center.

3-      Marhic, M. (2008). Fiber optical parametric amplifiers, oscillators and related devices. 1st ed. Cambridge, UK: Cambridge University Press.

4-      Optical Parametric Amplifier. (2014). [online] Available at: 1- http://en.wikipedia.org/wiki/Optical_parametric_amplifier [Accessed 4 Jun. 2014].

5-      Wikipedia, (2014). Parametric oscillator. [online] Available at: http://en.wikipedia.org/wiki/Parametric_oscillator [Accessed 3 Jun. 2014].

7-  Wikipedia, (2014). Amplifier. [online] Available at: http://en.wikipedia.org/wiki/Amplifier [Accessed 2 Jun. 2014].

Basic Relay Activation Through Simple Techniques

Assalam o Alaikum , Today I want to share my final assignment of Relay Activation through Simple techniques Using Transistors , Heat Sensors or Wireless Transmission. Hope you find it Informative.

Experiment 1 :

Energizing relay through Transistor :

Description:

In this Simple arrangement , we have got a transistor(BD 139) which is turned on by the signal on its base . When it is turned on, coil connected to it is energized and is responsible for the connection between common and normally open contact of the relay. Note that common is given 220vAC so that whenever there is a signal at the base of the transistor, connection between common and normally open contact derives any 220 volt load (e.g. Lamp in this case).

Experiment 2:

Modification for Digital Signals:

Description:

This is the modified circuit for operation at 5vdc (digital). We have used a comparator (LM324) and appropriate resistors to set this circuit operation at 5v. Whenever a signal is slightly greater than 5volt at the positive input of the comparator, its output will go high (24v) that will derive the transistor and energize the coil, in turn the Lamp would be energized as well.

Experiment 3:

Infrared Transmission:

Description:

This is the modified circuit for Infrared transmitter and receiver. Transmitter is connected with 4.7k resistor and Receiver is connected with reverse polarity (Cathode with Vcc) as compared to transmitter with 20k resistance. Its range can be modified by changing the value of the resistors. When there is no obstacle between the transmitter and receiver 0v (approx.) is received at receiver side. When there is anything in between, Receiver gets 24 volts across it, which turns on the transistor and coil is energized. As a result, Contact occurs between normally open and common of the relay and the lamp is ON.

Experiment 4:

Heat Sensor:

  

Description:

This Circuit contains LM35 which is a temperature sensor having ratings of 10mv/Celsius. Also, we have used non-inverting amplifier to increase the voltage for further use. So, when we heat LM35 temperature increases and in turn voltage at the positive terminal of amplifier increases. Rf and R1 set the gain of the amplifier and output voltage at A is received. Here, for example we have used a comparator with appropriate setup so whenever the temperature goes above 5 volt we receive a 24v signal at the comparator output that can further be used.

Experiment 5:

Stepper Motor:

 

Description:

This is stepper motor internal circuit. First of all we find the sequential wires that rotate the motor in correct and continuous direction. Then, connect them in sequential way like this circuit. Whenever you give transistors continuously voltage at their (either left to right or right to left) , the stepper motor will take steps according to the sequence. One transistor is responsible for a single step when turned on.

Experiment 6:
Stepper Motor Program (PLC):

A Stepper motor is to be operated in following pattern.
1- Data 0001 has to be rotated.
2- Data should be rotated every 3 seconds.
3- Rotation should be either left or right.
4- Program should have Master Start Stop control.
5- Stop button should reset all outputs.

I/O Table :


 

Ladder Diagram :

Description:

The Ladder diagram works in following pattern.

When you press the start button the output RUN is activated and the process is started. Input I0.3 initiates a timer T37 of 3 seconds. Input I0.0 selects the data movement to be either left or right. Input I0.1 moves in the data either 0001 or 0011. The combination of the timer and the left right control output is responsible for rotation of data in the desired direction. Master Stop resets any data present in the outputs.  

--Copyright : Muhammad Shahzaib S. Qureshi--

Difference Between Normal and Power Diode

Assalam o Alaikum ! Today I want to Share my Assignment of Power Electronics , Hope You find it Informative. 

Diode

Diode is a simple Semiconductor device which is used for many purposes in electronic applications.

Diode is specially known for conversion of AC to DC or Rectification process. It is opted for its unique characteristics such as Uni-Directional current provision and infinite resistance to the Reverse current.

SYMBOL:

Diode consists of two doped semiconductors, one of a P-type and other of N-type. When Tetravalent semiconductor is doped with pentavalent impurities , then electrons are the majority carriers and N-type semiconductor is formed. Secondly, P-type with holes as the majority carriers is formed, when trivalent impurities are added to the tetravalent semiconductor material. After that, P-type semiconductor and N-type Semiconductor are diffused together. By Diffusion, electrons from N-type region flow to P-type region and holes flow from P-type to the N-type region leaving behind negatively charged ions. In this process, electric field is created with opposite polarities to the respective (n-type or p-type) regions which blocks the further transfer of both carriers and as a result, a potential barrier is formed in between the semiconductors which is called Depletion region.

This PN juction can be used according to the need and in a controlled manner. It can be used in three modes, Zero bias , Forward Bias and Reverse Bias. In Zero Bias mode, it remains at its neutral behaviour. In Forward Bias mode, a potential difference is applied to the junction where P-type material is connected with the positive terminal and N-type is connected with the negative terminal of the Source.

When this arrangement is made , opposite polarity potential (w.r.t depletion region) breaks the potential barrier(inside) and flow of charges is started from both ends and as a result the current is observed.

In Reverse Bias, P-type is connected with negative terminal and N-type is connected with the positive terminal of the source.

This arrangement keeps the majority carriers of both materials away from breaking the depletion region and source potential(outside) attracts the majority carriers which results in increment of depletion region and a large voltage is observed.

Diodes are used in almost every electronic device both on small and large scales . However, diode needs some modification in high power applications. Diode undergoes some problems such as ability to conduct high current in forward bias and to hold high voltage and avoid breakdown in reverse bias. To overcome these problems, concept of Power diodes is introduced.

Power Diode

Power diode is built with vertical orientation to provide extra cross-sectional area which is required to handle large amount of current . The other problem of controlling breakdown voltage in reverse bias is overcome by controlling the relative factors.

Breakdown occurs due to the high electric field in potential barrier. Electric field and depletion width has inverse relation (E=V/d), so to control the break down at very high voltage, depletion width has to be altered, and to alter the depletion width, Doping of the material has to be changed. This is done by the following arrangement of normal and less doped semiconductors.

      

In this arrangement,an extra layer of N-type material is introduced. Here, N-type in the middle region is less doped and the other P-type and N-type materials are normally doped. When the diode comes in reverse bias mode, it sees a large potential barrier across the lightly doped N-type region, which makes it able to withstand more voltage than normal. Extra layer used here, has to provide required majority carriers to maintain the current without reduction during the forward bias mode.

Major Differences

1- Design

Simple diodes consist of a simple PN junction. They are smaller in size and lighter in weight, while power diodes are in modified form and they are larger and heavier normally. Power diodes are usually available in metal form.

2- Voltage Rating

Simple diodes are used in normal low power components so they have a relatively low voltage ratings as compared to power diodes. Power diodes can have very high voltage ratings usually in thousands of volts.

3- Current Rating

Power diodes have a high hand in Current ratings over normal diodes , that can be in several hundred amperes.

4-Temperature

Major probelm in handling high power applications is the generation of heat and temperature. Power diodes have the accessiblity of operation at higher temperature whereas normal diodes do not need this feature in high priority.

5- Cost

Power Diodes are costly as compared to the simple diodes due to the additional components and features.

Copyright : M.Shahzaib S. Qureshi

---------------------------------------------------- The End -----------------------------------------------

Quran Pak with Urdu-English Translations (Java-Mobiles + Android Link)

Assalam o Alaikum !

Today I want to share a software for Java Mobile Phones ( Almost every phone supports it ) ,
This is Quran Software with Urdu and English Translations.

This is the best one I have found so far , You can change the font size and colours as well of both Arabic and its Translations.

LINKS

1- Direct Download Here

OR

2- http://gallery.mobile9.com/f/1260654/

OR

3- http://www.cell11.com/download/s60v5/s60v5-softwares/new-apps/eIslamExplorer_V3_0.jar

Its size is 2.8 MB , if your mobile phone does not support it then try the basic version without translation .

LINKS

For Basic Quran:

Direct Download Here

OR

2- http://www.4shared.com/file/4bCoX6gH/eQuranExplorerAr_V2_0.html

Installation: 

1- You can directly download it from the cell phones (Smartphones)
2- You can download it to your pc and then transfer to your phone through respective software for your mobile ( PCsuite, Htc Sync etc.)
3- You can download it to PC, then transfer it to the memory card through card reader , then put memory card in your mobile, and install it from your mobile file browser(Gallery-MemoryCARD).
4. For Android Users Copy and paste this link in your mobile browser :

https://play.google.com/store/apps/details?id=com.eIslamExplorer

Jazakallah !

NOTE : This is a free software by Eislamexplorer.org , for their great work , you should visit and register yourself at their website on the address :

http://www.eislamexplorer.org/index.php?ID=Soft_0_0_0  ..

FM Transmitter

Assalam o Alaikum !

Today I want to share my first electronic project in my student life . which is a simple FM Transmitter.

Requirements :

1- Breadboard
2- Resistors , Capacitors as in figure
3- 9 volt DC Battery
4- Mic

Note: Don't buy Inductor as it wont work,until its in wounded wire shape and take a good mic with long legs :)

You have to make it yourself. You have to take a 15/22 gauge wire and wound it on anything with less diameter(pencil,pen,etc) or You can make it through this formula.

 L  = [d² n²] / [18d + 40l]

• Where’ L ‘  is the inductance in Micro Henries [µH]
• ‘d’ is the diameter of the coil from one wire centre to another wire centre. It should be specifies in inches.
• ‘l’ is the length of the coil specified in inches.
• ‘n’ is the number of turns.

Mine worked within 5,6 turns of 15 gauge wire on a HB-2 pencil. (Can vary Definitely :) )

Steps:

1- Wire all these components on the breadboard and importantly this circuit should take as little place as possible, try to make it congested and turn the long legs of the components into small legs ( By cutter ofcourse :) )

2- Now connect the DC battery and Tune the radio (e.g in Cellphone ), it would automatically tune a station without any voice output( means circuit is working) , Now you can sing Opera on the Mic :D..

3- You can introduce antenna with inductor capacitor combination (as in figure ) to extend the range.


Description :

1- R1,R2,R6 are DC biasing resistors for keeping the transistor Q1 forward Biased.
2- C1 is used to remove any DC signal in AC signal(voice from mic).
3- Transistor Q1 is just amplifying the voice signal which is in milivolts (mv)
4- Then again R4,R5,R8 are DC biasing resistors for Q2.
5- Now Q2 is amplifying the coming voltage and C7 and inductor are performing the Frequency Modulation.

Precautions :

Wiring should be congested , Mic should be connected with right polarity with the DC battery , Receiver should not be touching the inductor when the transmitter is on , Battery should at least be 6 volts.

You can use Circuit Maker from National Instruments .

Torrent Link :
http://thepiratebay.se/torrent/5295859/National_Instruments_Circuit_Design_Suite_11.0

Best Of Luck !!

How to Index Your Article on Google

Contact Usman Aljaidi he is a real Genius in this case :D

www.UsmanSaeedArab.blogspot.com