J
Joel Kolstad
- Jan 1, 1970
- 0
I think that most people are aware of the standard transforms used to
convert lowpass filter prototypes into highpass filters, bandpass filters,
etc. If you look at the result, it's clear that the bandpass filter, for
instance, is an 'interleaved' lowpass and high pass filter design. That
struck me as more coincidental than anything profound, but I've recently
learned that this interleaving is a more general result and apparently can
be done with many different LC filters. That is, if I have two, say, 3
section filters, I can match up the series and shunt sections in each filter
and interleave the two (shunt sections placed in parallel, series sections
placed in series).
So now I'm curious... how does this actually work? Is the idea just that
each starting filter must be operating at frequencies far enough apart from
one another that at any given frequency the components from one filter are
near-opens for shunt components and near-shorts for series components, so
that the two designs don't interact much? Or is there a more general
mathematical basis for why the interleaving works, and you could
successfully interleave something like a notch filter in the middle of a
bandpass filter?
Thanks,
---Joel Kolstad
(Who'll shortly need to be getting new bookshelves after acquiring copies of
Zverev, Matthei/Young/Jones, etc...)
convert lowpass filter prototypes into highpass filters, bandpass filters,
etc. If you look at the result, it's clear that the bandpass filter, for
instance, is an 'interleaved' lowpass and high pass filter design. That
struck me as more coincidental than anything profound, but I've recently
learned that this interleaving is a more general result and apparently can
be done with many different LC filters. That is, if I have two, say, 3
section filters, I can match up the series and shunt sections in each filter
and interleave the two (shunt sections placed in parallel, series sections
placed in series).
So now I'm curious... how does this actually work? Is the idea just that
each starting filter must be operating at frequencies far enough apart from
one another that at any given frequency the components from one filter are
near-opens for shunt components and near-shorts for series components, so
that the two designs don't interact much? Or is there a more general
mathematical basis for why the interleaving works, and you could
successfully interleave something like a notch filter in the middle of a
bandpass filter?
Thanks,
---Joel Kolstad
(Who'll shortly need to be getting new bookshelves after acquiring copies of
Zverev, Matthei/Young/Jones, etc...)