Lumped-element two-section branchline coupler MMIC

New for February 2023.  This content was split from our main branchline coupler page and is being expanded.

Here's a two-section branchline lumped-element branchline coupler in MMIC representation, with the quarter wavelength arms changed into lumped inductive and capacitive elements. It's a "double-box" structure on four-mil GaAs. It worked great at S-band, with less than 1 dB resistive loss in spite of all those spiral inductors! Such a structure can make an efficient power combiner for the IF output of a higher-frequency image-rejection mixer.

That MMIC does not have ground-signal-ground (GSG) interfaces for RF probing, which seems old-school.  But it's purely passive, so the yield of visually-good die is probably close to 100%.

Sorry, we don't have a design model of that MMIC! But we will offer this small insight: if the input port is on the upper left, the lower left  port is the isolated port, the upper right is the reference phase line and the lower right is 90 degrees delayed phase line.

There's a good chance we can dig up some more info on this design, we'll post it when we find it.