group delay equalisation of high-pass filter

Anyone know of any handy free programs that I can use to equalise the group delay of a high-pass elliptic filter (fc approx 1GHz), or a band-pass filter?

Cheers,

Phil

Reply to
Phil Newman
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I have, and it's not working, which is really annoying. it works fine for a low-pass filter, but with a high-pass network, with different frequency (higher) the networks do not even act as an all-pass filter.

So, does anyone know of any programs that can do this for me with correct answers??

Phil

Reply to
Phil Newman

Oh right,

I'll probably be doing the same. I got the spreadsheet to work, I was copying the numbers into ADS to simulate, and I found that the numbers were so sensitive to change. So the circuit I got is impractiable with normal inductors, so I guess tracks to replace the inductors is needed?

Cheers,

Phil

Reply to
Phil Newman

Cheers,

is there a mathematical method of transforming my inductor values to microstrip length/width rather than empirically guessing at wire lengths?

Reply to
Phil Newman

Just write yourself the calculation for an all pass network in Excel - it is only half a dozen lines.

d

Pearce Consulting

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Reply to
Don Pearce

Well, I'm not in the design business any more, but I once did this for a filter at about 1.5GHz on FR4. I ended up with a small network of fine tracks and chip capacitors. I used the theoretical numbers from my programme and estimated the track lengths that would make an equivalent inductance. A couple of iterations of boards was all it took.

d

Pearce Consulting

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Reply to
Don Pearce

Absolutely - use thinnish single strand copper wire flush against the board to breadboard, then measure and replace with etched copper track for the real thing.

d

Pearce Consulting

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Reply to
Don Pearce

Rough rule of thumb would be about a nanohenry to a millimetre for reasonably thin wire.

d

Pearce Consulting

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Reply to
Don Pearce

so "no" then....?

Reply to
Phil Newman

so "no" then....?

Reply to
Phil Newman

MDS? I have all the information necessary to calculate this.

Reply to
Phil Newman

The answer is yes, but it is complex, and depends on all sorts of factors like substrate material, distance to the cover, copper thickness etc. MDS should be able to help you.

d

Pearce Consulting

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Reply to
Don Pearce

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