higher order all pass filters

[meghana.s]

hey
i'm sort of a beginner to filters. if i wanted to realise a transfer function for a higher order all pass filter using passive components, how do i do that? i know that one of the methods for realising higher order active filters is by cascading second order filters. can the same method be employed here?
if you know of any study material or book let me know.
thanks
M

 

[ZekeR]

meghana, you can certainly cascade all-pass filters. In order to do this, it is generally a good idea to introduce an active element (an op-amp acting as a buffer) to prevent each subsequent stage from loading down the stage before it, or to cascade active all-pass filter stages.

Hope this helps

 

[meghana.s]

definitely helped....thanks

 

[Kral]

You can design passive all pass filters of any order. I know of no way to design a passive all pass filter without using both capacitors and inductors. A common configuration is the lattice network. See https://en.wikipedia.org/wiki/Lattice_phase_equaliser. Note, however, that these filters must be designed for a specific characteristic impedance. The use of an op amp buffer as ZokeR suggests eliminates this problem.