filters

LOW PASS FILTER

HIGH PASS FILTER

BAND PASS FILTER

BAND REJECT FILTER

By Anand KumarRoll no: 2012-70

Filters(Definitions)and their applications

• As name suggest it filters come contents of input signal and give desired output signal.

• In general electrical and electronics engineering sometimes it is desirable to have circuits capable of selectively filtering of one frequency or range of frequencies out of a mix of different frequencies in a circuit.

• A circuit designed to perform this frequency selection is called a filter circuit, or simply a filter best example is the FM or frequency modulation that we use in our daily life

• The filter circuits can be made by two components :-

• 1. PASSIVE• 2. ACTIVE

BANDPASS FILTER

LOWPASS FILTER

HIGHPASS FILTER

TYPES OF FILTER☺ BAND STOP FILTER

LOW PASSFILTER

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• An ideal low-pass filter is a circuit which passes low-frequency signals and block high-frequency signals.

• There are three basic kinds of circuits capable of accomplishing this objective, and many variations of each one:-

• First-order filter• Second-order filter• Higher-order filter• Active electronic realization

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CIRCUITDIAGRAM

• An RLC circuit is an electrical circuit consisting of a resistor, an inductor, and a capacitor, connected in series or in parallel.

• A second-order filter attenuates higher frequencies more steeply. The Bode plot for this type of filter resembles that of a first-order filter, except that it falls off more quickly.

Second order low pass filter(RLC filter)

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Higher order passive filters

WE CAN USE MORE CASCADED RC ALONG WITH SERIES

Active low pass filter(with opamp)

May 2, 2023

Another type of electrical circuit is an active low-pass filter.In the op-amp circuit shown in the figure, the cutoff frequency (in hertz) is defined as:

or equivalently (in radians per second):

The gain in the pass band is −R2/R1

PASSHIGHFILTERS

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High pass filters using LC components, i.e. inductors and capacitors are arranged in ether a pi or T network. As suggested by its name, the pi network has one series component, and either side of it there is a component to ground. Similarly the T network high pass filter has one component to ground and either side there is a series in line component. In the case of a high pass filter the series component or components are capacitors whereas the components to ground are inductors. In this way these filters pass the high frequency signals, and reject the low frequency signals. These filters may be used in applications where there are unwanted signals in a band of frequencies below the cut-off frequency and it is necessary to pass the wanted signals in a band above the cut-off frequency of the filter.

HIGH pass filter(RLC filter)

Active HIGH pass filter(with op-amp)

May 2, 2023

Figure shows an active electronic implementation of a first-order high-pass filter using an opamp. In this case,the filter has a passband gain of -R2/R1 and has a cutoff frequency of

Because this filter is active, it may have nonunity passband gain. That is, high-frequency signals are inverted and amplified by R2/R1.

FILTERBANDPASS3

Band pass filter

• A band-pass filter is a device that passes frequencies within a certain range and rejects (attenuates) frequencies outside that range.

• These filters can also be created by combining a low-pass filter with a high-pass filter.

• The bandwidth of the filter is simply the difference between the upper and lower cutoff frequencies.

• Q factor:-• A band-pass filter can be characterised by its Q factor. The Q-factor

is the inverse of the fractional bandwidth. A high-Q filter will have a narrow passband and a low-Q filter will have a wide passband. These are respectively referred to as narrow-band and wide-band filters.

May 2, 2023

Band pass with LC components• Like the high pass filters and

the low pass filters, there are two topologies that are used for these filters, namely the Pi and the T configurations. Rather than having a single element in each leg of the filter as in the case of the low pass and high pass filters, the band pass filter has a resonant circuit in each leg. These resonant circuits are either series or parallel tuned LC circuits.

Main terms

May 2, 2023

• GAIN• SLOPE• BANDWITH• Frequency

response• fH = High

frequency • fL = Low

frequency

Basic RC based band pass filter

May 2, 2023

Active Band pass filter

May 2, 2023

Active bandpass filter with stages

May 2, 2023

BAND STOP ORBAND REJECT

FILTER4

Band stop or band rejection filter• In signal processing, a

band-stop filter or band-rejection filter is a filter that passes most frequencies unaltered, but attenuates those in a specific range to very low levels.

• It is the opposite of a band-pass filter. A notch filter is a band-stop filter with a narrow stop band (high Q factor).May 2, 2023

band stop filter( WITH RC )

May 2, 2023

Active band stop filter

May 2, 2023

These are classified as:• Wide band reject filters• Narrow band reject

filters (Notch filters).

Wide band reject filtersNarrow band reject filters (Notch filters).

REFREN

CES

My friends & teachers

http://www.radio-electronics.com/

http://en.wikipedia.org/wiki/Band-stop_filter

http://www.allaboutcircuits.com/vol_2/chpt_8/5.html

http://www.circuitstoday.com/band-stop-filter

THANKYOU