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

[pigrew]

I have minimal experience with ADS, but my feeling is that you'll need to go the opposite way: Draw the layout and simulate it using Momentum (or HFSS?), and import that s-parameter block into ADS.

ADS seems to have some documentation on that simulation flow.

[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 ?

[tec5c]

You're asking to transform a cell (MCP) which is two straight lines into a spiral. This is not practical. So you need to look at alternatives.

You can use pre-existing spiral cells available in default ADS library. Such as; MSIND, MRIND, MSSPLS_MDS, MSSPLC_MDS and so on. All of these have layouts associated to them.

You can use a PDK which has spiral inductors and layouts. (Least probable option, mainly aimed at design houses).

You can manually design the spiral inductor layout yourself, then run EM sim. to optimise the design to your liking and use the layout as a cell in your circuit design.

Or you can manually design the entire balun within the layout window and run EM sims on the whole design (most common option).

[promach]

Or you can manually design the entire balun within the layout window and run EM sims on the whole design (most common option).

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 ?

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

And why need to increase Zoe/Zoo impedance ratio ?

[promach]

 See https://github.com/promach/planar_marchand_balun

I suppose I made mistake in the width of the coupled microstrip (W=2mm) in terms of ports impedance of 50 ohm ??