Standard T, π, L Sections, Characteristic impedance, image transfer constants, Design of Attenuators, impedance matching network, T and π Conversion, LC Networks and Filters: Properties of LC Networks, Foster’s Reactance theorem, design of constant K, LP, HP and BP Filters, Composite filter design

1. prepared by
D V S Ramanjaneyulu
Asst.professor
Ace engineering college
1
UNIT-5
ATTENUATORS &FILTERS

2. Syllabus ……
2
Characteristic impedance, image transfer
constants,.
Design of Attenuators, impedance
matching network.
T and π Conversion.
LC Networks and Filters: Properties of
LC Networks, Foster’s Reactance theorem.
design of constant K, LP, HP and BP
Filters, Composite filter design.
Problem solving.

3. 3

4. FILTERS
Definition : Filters are frequency selective networks that attenuate signals
at some frequency and allow others to pass with or with out attenuation
Properties of filters
A Filter is constructed from purely reactive elements
Ideally filters should produce no attenuation in the desired band called
pass band and should provide attenuation at all other frequencies called
attenuation band or stop band
The frequency which separates the pass band and he stop band is called cut-off
frequency.
Applications of filters

5. Classification of filters :
On basis of frequency characteristics filters are classified
in to four types
i. Low Pass
ii. High Pass
iii. Band Pass
iv. and stop
Low Pass Filter : A low pass filter allows all frequencies
up to a certain cut-off frequency to pass through it
and attenuates all the other frequencies above cut off
frequency
High Pass Filter : A high-pass filter attenuates all the
frequency below the cut- off frequency and allows all
other frequencies above the cut-off frequency
Band Pass Filter :A band-pass filter allows a limited band
of frequencies to pass through it attenuates all other
frequencies below or above the frequency band
Band stop Filter : A band-stop filter attenuates a limited
band of frequencies but allows all other frequencies
to pass through it

6. Characteristics of ideal filter

7. Characteristics of Practical
filter

8. CHARACTERISTICS IMPEDANCE OF T NETWORK
Definition : The value of load resistance at which power transfer is maximum and
hence network experiences minimum losses is called Characteristic Impedance

10. PROPAGATION CONSTANT(γ) OF T NETWORK
THE current leaving any section will be definite
proportion of that entering section and in general will
Be out of phase with it.

11. CHARACTERISTICS IMPEDANCE OF ∏ NETWORK