LOW PASS FILTERBy: Ayesha Saeed
INTRODUCTION Most of the signals we deal with in real life getcorrupteed in some way or another by someunwanted signals....
 A Filter is an electronic circuit that removes /attenuates, from a signal, some unwanted componentor feature. Filter Ap...
FILTER CHARACTERISTICS:To understand the basics of filtering, it is firstnecessary to learn some important terms used tode...
Stop Band: The range of frequencies that is filtered out.Pass Band: The range of frequencies which is letthrough and recor...
LOW-PASS FILTER: A low-pass filter is an electronic filter that passeslow-frequency signals and attenuates (reducesthe am...
There are two basic kinds of circuits capable ofaccomplishing this objective, and many variations ofeach one: The inducti...
THE INDUCTIVE LOW-PASS FILTERThe inductors impedance increases with increasingfrequency. This high impedance in series ten...
THE RESPONSE OF AN INDUCTIVE LOW-PASS FILTER FALLSOFF WITH INCREASING FREQUENCY.
THE CAPACITIVE LOW-PASS FILTER The capacitors impedance decreases with increasingfrequency. This low impedance in paralle...
THE RESPONSE OF A CAPACITIVE LOW-PASS FILTER FALLSOFF WITH INCREASING FREQUENCY.
 All low-pass filters are rated at a certain cutofffrequency. The cutoff frequency for a low-pass filteris that frequency...
 A simple filter will be two elements - a capacitor orinductor and a resistor. A capacitor will tend to "trap"low frequen...
 There are a great many different types of filtercircuits, with different responses to changingfrequency. The frequency r...
First-order filter:A first-order filter, will reduce the signal strength byhalf (about −6 dB) every time the frequency dou...
SECOND-ORDER FILTER A second-order filter does a better job of attenuatinghigher frequencies. The Bode plot for this type...
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Ayesha low pass filter

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Ayesha low pass filter

  1. 1. LOW PASS FILTERBy: Ayesha Saeed
  2. 2. INTRODUCTION Most of the signals we deal with in real life getcorrupteed in some way or another by someunwanted signals. For the purpose of signal processing and analysis, it isimperative to get rid of these interferences, or at leastreduce their effects. This is achieved through applying Signal Filteringtechniques.
  3. 3.  A Filter is an electronic circuit that removes /attenuates, from a signal, some unwanted componentor feature. Filter Application Eliminate background noise Radio tuning to a specific frequency Direct particular frequencies to different speakers Modify digital images Remove specific frequencies in data analysis
  4. 4. FILTER CHARACTERISTICS:To understand the basics of filtering, it is firstnecessary to learn some important terms used todefine filter characteristics. Cut-Off Frequency (fc): Also referred to as thecorner frequency, this is the frequency orfrequencies that define the limits of the filterrange.
  5. 5. Stop Band: The range of frequencies that is filtered out.Pass Band: The range of frequencies which is letthrough and recorded.Transition Band: Region that Separates the pass bandand stop band.
  6. 6. LOW-PASS FILTER: A low-pass filter is an electronic filter that passeslow-frequency signals and attenuates (reducesthe amplitude of) signals with frequencies higherthan the cutoff frequency. The actual amount ofattenuation for each frequency varies from filter tofilter. It is sometimes called a high-cut filter, or treble cutfilter when used in audio applications.
  7. 7. There are two basic kinds of circuits capable ofaccomplishing this objective, and many variations ofeach one: The inductive low-pass filter The capacitive low-pass filter
  8. 8. THE INDUCTIVE LOW-PASS FILTERThe inductors impedance increases with increasingfrequency. This high impedance in series tends toblock high-frequency signals from getting to the load.
  9. 9. THE RESPONSE OF AN INDUCTIVE LOW-PASS FILTER FALLSOFF WITH INCREASING FREQUENCY.
  10. 10. THE CAPACITIVE LOW-PASS FILTER The capacitors impedance decreases with increasingfrequency. This low impedance in parallel with theload resistance tends to short out high-frequencysignals, dropping most of the voltage across seriesresistor R1.
  11. 11. THE RESPONSE OF A CAPACITIVE LOW-PASS FILTER FALLSOFF WITH INCREASING FREQUENCY.
  12. 12.  All low-pass filters are rated at a certain cutofffrequency. The cutoff frequency for a low-pass filteris that frequency at which the output (load) voltageequals 70.7% of the input (source) voltage. Thiscutoff percentage of 70.7 is not really arbitrary, allthough it may seem so at first glance. In a simplecapacitive/resistive low-pass filter, it is the frequencyat which capacitive reactance in ohms equalsresistance in ohms. In a simple capacitive low-passfilter (one resistor, one capacitor), the cutofffrequency is given as:
  13. 13.  A simple filter will be two elements - a capacitor orinductor and a resistor. A capacitor will tend to "trap"low frequencies. In the case of a low pass filter made of a capacitorand resistor, the output voltage will be measuredacross the capacitor. Inductors are the opposite, so the output would beacross the resistor.
  14. 14.  There are a great many different types of filtercircuits, with different responses to changingfrequency. The frequency response of a filter isgenerally represented using a Bode plot.• First-order filter• Second-order filter• Third and Higher order filters
  15. 15. First-order filter:A first-order filter, will reduce the signal strength byhalf (about −6 dB) every time the frequency doubles.The magnitude Bode plot for a first-order filter lookslike a horizontal line below the cutoff frequency, and adiagonal line above the cutoff frequency.
  16. 16. SECOND-ORDER FILTER A second-order filter does a better job of attenuatinghigher frequencies. The Bode plot for this type offilter resembles that of a first-order filter, except thatit falls off more quickly. For example, a second-order filter will reduce thesignal strength to one fourth its original level everytime the frequency doubles.
  17. 17. THANK YOU
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