Analog filter design metgod questions

Could be. I did not check because I already have it. It should be on the web someplace.

I only mentioned it because I thought it was free. Maybe free availability has diminished. The book is okay, and has the transformations in question. I don't know if I would pay for it. It is very professor-ish. It is nicely typeset.

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Thanks, that makes sense. Loudspeaker efficiency behaves the same way, for much the same reason--you have to knock down the peaks becaose it's hard to fill in the valleys.

Cheers

Phil Hobbs

Thanks. I have used these transformations in the past, and they have worked fine. My initial queries were more related to the text book treatment of this topic, and almost always it starts with a prototype low pass filter, with a set of initial conditions (e.g., max. allowed pass band deviation from idea(dB) etc.,) Then one determines the filter order, and then does a table look up or constructs the transfer function, followed by frequency and impedance scaling, and if needed a transformation to another type (high, band, band stop etc.,) Fine, My question was suppose one were to start with a high pass filter, then what would the set of initial conditions be ?

So very true. But opamps, sonner or later, hit the gain-bandwidth product constraint. I am more interested in ladder networks, in the RF and microwave frequency ranges.

If you know all about them, just plug them in and do the algebra. The answers to your original question require about two lines of algebra each.

Cheers

Phil Hobbs

In addition there is typically some nasty "overshoot" in the gain (as a function of frequency) around the corner frequency.

I think that's often true. I recall reading about it as a kid, in the 1973 National Semi Audio Handbook, in the context of active crossover networks.

Cheers

Phil Hobbs

The Filter Solutions/Nuhertz people have great software for designing exotic LC filters. We spent a week trying to design a post-DAC LC lowpass filter by hand, and the software did it in minutes. I think they also have software for designing microwave transmission line filters.