Ssn Assignment

8/8/2019 Ssn Assignment

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FILTERS

My assignment topic is filters.

Basically filters are a very important

tool and topic in electronics. Their

presence can make many complicated

things possible.

We must be wondering why do we actually need

filters. When we are actually analyzing any signalwe can get many unwanted signals in our presentsignal. Also we can use a filter in many of our

electronic devices to vary the type of work we aredoing. First we analyze the type of filters.

Basically there are 4 types of filters:-


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1) Low pass filter

2 ) H igh pass filter


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3) Band pass filter

4 ) Band Stop Filter


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For example we are sitting in a room with a fan working.If we are speaking something then that is a signal.

Speech signal has a frequency from 0.3 Hz to3.4KHz.both these signals will try to interfere with each

other.

Speech Signal


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N oise Signal

Looking at these two signals we cannot possiblyseparate them in time domain but we can separate themin frequency domain using filters.We can see that noise

signal has more frequency content than the speech

signal. So we can plot their frequency curves withamplitude and then use a low pass filter to separate our

speech signal from noise.


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Speech Signal

N oise Signal So here we can use a low pass filter to pass our speechsignal and get it.


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Another exampleAnother use can be made when we transmit signalfor mobile phones. They transmit signal forfrequency of the range 890-915 MHz or 935-960MHz. If there are other distortions we can use a

band pass filter to pass our desired band.

Another example


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Sometimes certain frequencies are not required. Likesuppose in a system we are giving an input signal of a

certain frequency but we have an incoming frequency notdesired in the output. Then we can use a stopband filter.

Bandpass and band-rejection filters have been widely usedto control the flow of signals that propagate in electronic

circuits. A bandpass filter is an electrical filter used to passthe spectral components of a signal falling within a

predetermined range of frequencies while attenuating thefrequency components above and below that range. A bandrejection filter, however, is an electrical filter that rejects or suppresses a band of frequencies. A low pass filter passes

low frequency electrical signals, while rejects highfrequency electrical signals. Conversely, a high pass filter


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suppresses the frequency electrical signals, while passeshigh frequency signals.

NUMERICAL EXAMPLE


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APPLICATION


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one of th e mai n applicati ons of f ilt er circuit s is th e use of th em in cre ati ng digital mu sic a nd mixi ng

th em a s done by DJ' s.

Cre ati on of digital mu sic is also done using f ilt ers. The filter is one of a producer's must have tools intheir arsenal. Filters allow you to greatly shape the

sound that you are effecting, by isolating certainfrequencies from the ones that remain. Subtractive

synthesis was founded on this idea, and the result of their influence was been seen in just many syntheticmusic pieces over the years. All frequencies that we

hear reach a cutoff point, which is the main part


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control of the filter. There are many different types of filters that can be used in combination with each

other to get some pretty drastically altered sounds.

APPLICATION

Application in opto- electronics

Devices and techniques for achieving signal filteringin RF or microwave frequencies by optical filtering

via two optical resonators in two separate opticalpaths. One optical resonator is tunable to tune thefiltering in RF or microwave frequencies. Tunable

opto--electronic oscillators may be constructedbased on described filters

APPLICATION

Use in speakers syst ems

"Filters" is an application for the calculation of electronic filters for the construction of speaker

systems. The program automatically calculates thevalues of electronic components (inductors,

capacitors) of electronic filters as a function of thespeaker impedance and the cutoff frequency

desired. The software can calculate and design their circuits (filters) for high, medium, low, sub woofer,


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etc. ... for different filter orders (first and secondorder). Once calculated the filtering circuit diagram

you can see the relative frequency and phase (Bodeplots)

.


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APPLICATION

Noise re movers.

They a re re move unwant ed no ise sign als over large range of freq uen cies for a l ot of devices.

APPLICATION

we ha ve so ma ny radi o stati ons and all of th em

are presen t at a di fferen t freq uen cy. Our f m radi o syst em ha s a f ilt er that i s ba nd pa ss f ilt er. As we rotat e our kno b th e pa rticula r f ilt er will move over

th e range of freq uen cies and will pass on ly th e


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For a grid-connected converter with an LCL filter,the harmonic compensators of a proportional-resonant (PR) controller are usually limited to

several low-order current harmonics due to systeminstability when the compensated frequency is outof the bandwidth of the system control loop. In this

paper, a new current feedback method for PRcurrent control is proposed. The weighted average

value of the currents flowing through the twoinductors of the LCL filter is used as the feedbackto the current PR regulator. Consequently, the

control system with the LCL filter is degraded froma third-order function to a first-order one. A largeproportional control-loop gain can be chosen to

obtain a wide control-loop bandwidth, and thesystem can be optimized easily for minimum

current harmonic distortions, as well as systemstability. The inverter system with the proposed

controller is investigated and compared with thoseusing traditional control methods. Experimental

results on a 5-kW fuel-cell inverter are provided,and the new current control strategy has been

verified.


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Angular s e l ective l i gh t f i l te r ba s ed o n ph o t o n ic c ry s t al fo r ph o t ovo l t a ic appl ic a ti o n s

A new angular selective filter design that isbased on photonic bandgap engineering

principles. The operation of the filter is basedon the occurrence of angular-dependentphotonic stopbands and passbands in a

photonic crystal structure. Such a filter allows

for the propagation of normally incident lightwhile disallowing the propagation of obliquelyincident light waves. When the filter is applied

to a solar cell structure that consists of adiffraction grating structure on the back surface,

a high-efficiency light trap can be formed.

Hence, the light-trapping capacity of the newstructure is dependent on the photonic band

structure of the light filter rather than onrefractive optical properties of the active

photovoltaic material. This paper presents amodel of such a structure and investigates the

possibilities afforded by the new structureOTHER APPLICATIONS

Digital f ilt ers are use d in a varie ty of


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commu nication syst ems which typically t rans mit and re ceive amplitud e and/ or pha se modulat ed

sign als ac ross a c ommu nication cha nne l. Radio syst ems using spre ad spect rum m odulati on t echniques are becoming incre asing ly popula r for

a variety of commu nication applicati ons. Radio t rans mitt ers and re ceivers req uire f ilt ers t o re move

or supp ress unwant ed freq uen cies from b eing

t rans mitting or re ceived. Surf ac e ac oustic wave (SAW) f ilt ers are freq uen tly u se d in comm er cial

and oth er applicati ons as RF and IF f ilt ers t o provide freq uen cy se lectivity a nd oth er e lect ron icf unctions. A surf ac e ac oustic wave f ilt er formed of

such a n SAW (surf ac e ac oustic wave) d evice includ es a pi ezoe lect ric sub st rat e on which a re formed int er digital t rans duc ers (IDTS) ha ving

int er digital e lect rodes and ref lect ors ha ving grati ng e lect rodes. Bandpa ss and ba nd-reje ction f ilt ers

ha ve been widely use d t o con t rol th e f low of

sign als that p ropa gat e in e lect ron ic circuit s. Aba ndpa ss f ilt er is an e lect rical f ilt er use d t o pa ss

th e spect ral c omp onen t s of a sign al f alling within apre det er mine d range of freq uen cies while


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att en uati ng th e freq uen cy c omp onen t s ab ove andbelow that range. A ba nd reje ction f ilt er, however,

is an e lect rical f ilt er that reje ct s or supp resses aba nd of freq uen cies. A low pa ss f ilt er pa sses low freq uen cy elect rical sign als, while reje ct s highfreq uen cy elect rical sign als. Converse ly, a hi ghpa ss f ilt er supp resses th e freq uen cy elect ricalsign als, while pa sses high freq uen cy sign als.

Shikha Bhatt

Roll no-907139

EEE-3


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