I would like to know, Is it possible to design digital all pass filter for specific frequency range of the system to alter the phase of the system in that specific range of frequency? If yes how ?
this can be accomplished by designing low pass all pass filter by connecting the input to an R-C passive low ass filter whose output is connected yo the noninverting amplifier input. The filter input is connected at the same time to a feedback potential divider with equal resistor.
It results in a transfer function having the following form:
H(s)= (S-Z0)/(S+P), eqn 1
where z0 is a zero and P is a pole.
both Z0 an P are real. Also Z0and P are equal in magnitude.
It results that the gain of the filter is eqaul to 1 at all the pass band frequencies.
Using binomial transformations to transform H(s) to H(z), one can can get the equivalent low pass all pass filter design.
The binomial transformation are:
s= (z-1)/(z+1),
the analog frequency wa= tanh wd/2
wd= 2 pi fc/fs
fc is the cut off frequency
and fs is the sampling frequency
fc= p/2 pi
Using these expressions you can transform eqn 1 to H(z) form which are digitally implementable.
For more information please follow the handouts in the link:Presentation Infinite Impulse response digital filter design-Handouts
By searching the web you can get a digital implementation of such circuit. Best wishes
this can be accomplished by designing low pass all pass filter by connecting the input to an R-C passive low ass filter whose output is connected yo the noninverting amplifier input. The filter input is connected at the same time to a feedback potential divider with equal resistor.
It results in a transfer function having the following form:
H(s)= (S-Z0)/(S+P), eqn 1
where z0 is a zero and P is a pole.
both Z0 an P are real. Also Z0and P are equal in magnitude.
It results that the gain of the filter is eqaul to 1 at all the pass band frequencies.
Using binomial transformations to transform H(s) to H(z), one can can get the equivalent low pass all pass filter design.
The binomial transformation are:
s= (z-1)/(z+1),
the analog frequency wa= tanh wd/2
wd= 2 pi fc/fs
fc is the cut off frequency
and fs is the sampling frequency
fc= p/2 pi
Using these expressions you can transform eqn 1 to H(z) form which are digitally implementable.
For more information please follow the handouts in the link:Presentation Infinite Impulse response digital filter design-Handouts
By searching the web you can get a digital implementation of such circuit. Best wishes