FiltersProvided by :

- Imad Gourrad

- Achraf Kalakhy

Framed by :

Mr.Ahmed Neddami

OUTLINE :

• 1- Filter definition .

• 2- Advantages and desadvantages of filters .

• 3- Low pass filter .

• 4- High pass filter .

WHAT IS A FILTER

GENERAL• They are used in circuits

which require the separation of signals according to their frequencies

• They are widely used in communication And signal processing

COMMONLY USED FILTERS

• The most commonly used filters are :• Low Pass Filter• High Pass Filter• Band Pass Filter• Band Reject Filter• All Pass Filter &• Universal Filters.

The Advantages of Each Filter Type

PASSIVE ACTIVE

• No power supply required

• they Can handle large currents and high voltages

• they include few components

• they have no bandwidth limitation

• ...

• No inductors

• Easier to design

• Can produce high gains

• Generally easier to tune

• Small in size and weight

• …

passive filters require no power supply , they can handle large currents and high voltages and are very reliable , they include few components and they hav no bandwith limitations

while active filters include no inductors ,are easier to design, can produce high gains ,generally easier to repair and they are small in size and weight

Now we move to

While The Disadvantages of Each Filter Type for

PASSIVE ACTIVE

•Include large inductors for lower frequencies .

•Some of them require shielding

•Are produced in limited standard sizes

•Requiring variable inductors

•Must be designed with output and input consideration in mind

• Power supply required

• Can require many components

passive filters include large inductors for lower frequencies while some of them require shielding they are produced in limited standard sizes requiring variable inductors they must be designed with output and input consideration in mind

while active filtersrequire a power supply and can require many components

Low Pass Filter

Passive Low Pass Filter• In this type of filter the input

signal Vin is applied to the series combination

• But the output signal Vout is taken across the capacitor only this type of filter is known generally as a first order filter

Active Low Pass Filter

• The most common and easily understood active filter is the active low pass filter

• Its principle of operation and frequency response is exactly the same as those for the previously seen passive filter

FREQUENCY RESPONSE OF LOW PASS FILTER:

FREQUENCY RESPONSE OF LOW PASS FILTER:

•  At very low frequencies, ƒ < ƒc

•  At the cut-off frequency, ƒ = ƒc

• At very high frequencies, ƒ > ƒc

High Pass Filters

• 1 – passive high pass filter • 2 – active high pass filter

Passive High Pass Filter

• A High Pass Filter or HPF, is the exact opposite of Low Pass filter circuit, it is an electronic filter that passes high-frequency signals but attenuates signals with frequencies lower than the cutoff frequency .

• The High Pass Filter Circuit

Frequency Response of a High Pass Filter

A high pass filter is a circuit whose amplitude

response increases with f as shown in figure.

This filter passes frequencies that are higher than

the cutoff frequency Fc and rejects those that are

lower than fc .

That is, the pass band is f > fc

the bandwith can be obtained by reducing the stop band range

Cut-off Frequency

The circuit gain Av is calculated as:

At low frequency , when Xc is infinitly high , Vout = 0

At high fre , when Xc tends to be null , Vout = vin

Active High Pass Filter

• The basic electrical operation of an Active High Pass Filter (HPF) is exactly the same as we saw for its equivalent RC passive high pass filter circuit, except this time the circuit has an operational amplifier or op-amp included within its filter design providing amplification and gain control.

• Like the previous active low pass filter circuit, the simplest form of an active high pass filter is to connect a standard inverting or non-inverting operational amplifier to the basic RC high pass passive filter circuit as shown.

• First Order Active High Pass Filter :

Cut-off Frequency and Phase Shift

Cutoff frequency is the same to the passive high pass filter

THANK

YOU…!!!