Marchand balun layout

[promach]

For this marchand balun schematics in ADS, how to instruct the ADS layout generator to use coil shape (for area saving in IC) ?

Besides, anyone have any experience with planar layout of marchand balun on PCB ?





balun schematics







generated balun layout not in coil shape







balun layout in coil shape

[volker@muehlhaus]

1) ADS doesn't convert to physical layout (dimension) if your schematic has electrical parameters (impedance).
2) If your schematic has straight coupled line, that is what you get in layout.
3) There is no predefined layout element for such interleaved inductors, unfortunately.

So there is a lot of manual layout work ahead.

[promach]

Someone else told me to replace CLIN with 2 Symmetrical Coupled Microstrip Lines (MCP) and then use linecalc to get the correct length and width.

What do you think about this idea ?

[volker@muehlhaus]

Someone else told me to replace CLIN with 2 Symmetrical Coupled Microstrip Lines (MCP) and then use linecalc to get the correct length and width.
What do you think about this idea ?

Yes, that's fine, but it will be straight lines.

[promach]

So there is a lot of manual layout work ahead.

Yes, I am now trying to replicate planar layout of marchand balun on PCB using SonnetLite instead.

This book Microstrip Filters for RF Microwave Applications has some good examples (maths theory + implementation) on microstrip filters, but not balun.

[promach]

How do we see from the following expressions that even-mode to odd-mode impedance ratio is very important for balun ?

[promach]

How to derive the expressions involving Ya， Yb， Zoe，Zoo ?

And why need to increase Zoe/Zoo impedance ratio ?