Filters can be classified in many ways based on the
componets using, implementation etc
Implementation means either analog techniques or digital
In analog the main classification is active and passive
filters made of simple R,L,C elements are refered as
passive filters. when we are using some active components
like opamps, transistor along with passive components it
becomes active filters. the main advantage is that we can
vary the gain and other parameters easly in active filters.
Now depending on the application and neccisity we are going
for the diffreant forms such as low pass, high pass etc.
now we can see that all these filters are made of some
hardware components, so noise is an important factor which
will affects its accuracy.
so noise free design can be accomplished with the help of
digital filters which is based on algorithms. 2 basic forms
of digital filters are FIR and IIR filters. FIR filters can
be designed in many methods , one of such method is
windowing methods. some of IIR filters are butterworth
filter, chebyshev filter(type 1 and 2), cauver filters.
basic approach in design of IIR filter is first design
the filter in analog domain and then transform it into
now the latest trend of filters which are widely using in
navigation, control applications is kalman filters
discoverd by R.E kalman.it is an adaptive type filter. it
not only removes the noise but also helps in esimating the
differant states of a system which are not measuable( for
more info kindly go through state space modelling)
filters are classified in different types.
in passive filters different types based on type of
components are used.
A)RC low pass
B))RC high pass
C)RC band pass
D)RC band reject
in LC type components used
A)LC low pass
B)LC high pass
C)LC band pass
D)LC stop band
2)Active type classified four types
A)Active low pass
B)Active high pass
C)Active band pass
D)Active stop band
interviewr asked about sampling theorem and i said the
common def.(i.e ...sam freq must >=s max freq in the signal
for a sampled signal to recover without alising).he asked
that i have a sin signal of freq 1hz and i sampled at two
zero amplitude points can it be recoverable without
. If we have a parallel plate capacitor of plate area 'A'
and plate separatoin t and having a capacity C and a
metallic plate r of area A and of negligible thickness is
introduced in the capacitor at a distance from either of
the two plates as shown in the given figure then the
capacity of the capacitor will become
a.) b.) C c.) 2C d.) 4C