CPW coplanar waveguide circuit design

Hi,

This might be a very easy question but I don't have an idea on where to start with CPW circuit design.
I have been using ADS to design a microstrip circuit since it has Tlines components where you can actually select for a BPF design the characteristics of it and it will give you all the dimensions of the design based on the characteristics of your substrate.

This option as far as I know is not available for CPW, it is for waveguides and striplines. So I don't know how to design a CPW. It seems that from equations it could take ages to design a simple detector circuit.

Any tips would be very useful. The idea that I have is that maybe I could do the circuit design in microstrip and somehow modify that initial design to CPW.

Thanks for your help.

I also faced this problem with the limited CPW library in schematic. I got used to work directly in Momentum to simulate coplanar structures.
I am also interested in a solution for a more extensive library in schematic.

Thanks for your reply
can you describe briefly the design process you follow in momentum for a BPF or other design.

Many thanks

There are two ways to design CPW in Momentum:
1- map metal as strip and use differential ports
2- map metal as slot and use coplanar ports

in 2nd case you actually only draw the gap between the lines and stimulate the gaps with the coplanar ports. This is a bit confusing the very first time but way faster regarding computing time.

Then I draw the structure and let the optimizer doing its job with the standard parameters or perturbation optimization. One critical point if you don't have a grounded CPW is the air-bridge. I never had to optimize with air-bridges.

Hi thanks a lot.
Could I use as a starting design tools for microstrip to design for example an impedance matching circuit and then follow your design methodology?

Also, another beginner question if I have a conductor backed cpw do I still need air bridges?

Thanks again

hi every one ....
can u send how to design and simulate the coplanar waveguide structure in cst studio.....
thank u

U can take the help provided in the CST itself as it contain lot of examples which are simulated.