microstrip gap capacitors

[Philip Newman]

I am implementing a dog bone filter structure in microstrip. this includes
coupling capacitors which have to be realised on-chip. I have decided to
use gap capacitors, which is just a gap between microstrip lines. my
question is this. I have the capacitance value, how can I calculate the gap
space, S, and the width of the microstrip line, W?

Any ideas would be greatly appreciated.

Phil

 

[Don Pearce]

I am implementing a dog bone filter structure in microstrip. this includes
coupling capacitors which have to be realised on-chip. I have decided to
use gap capacitors, which is just a gap between microstrip lines. my
question is this. I have the capacitance value, how can I calculate the gap
space, S, and the width of the microstrip line, W?

Any ideas would be greatly appreciated.

Phil

The situation is far more complex than this. The capacitance actually
resolves into a pair of caps to ground, and a series cap. There is no
closed-form equation to calculate these, but I suggest you get hold of
a copy of "Foundations of microstrip circuit design" by T. C. Edwards
and have a read of the series gap pages.

d

_____________________________

http://www.pearce.uk.com

 

[Philip Newman]

bugger.

I know what you mean, I have seen the circuit topology. Terry Edwards book
is very good, and hopefully explain it!

cheers

Phil

 

[Patrick Bolton]

Philip,

Try looking on the Eagleware web site, in their forum section I seem to
remember an article by Randy on this subject

Patrick B

 

[Philip Newman]

not registered with them, but I think we have the problem sorted.

thanks anyway

Phil