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Millimeterwave packaging

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New for November 2020: the  topic of millimeter-wave packaging of MMICs is extremely relevant in today's 5G/SatCom/SIGINT/EW worlds. X and Ku-band packaging technology does not scale well to 40 GHz; you must pay more attention to wire-bond geometry (and compensation), vertical and horizontal package transitions, and cavity effects. That cheap over-mold goop you used at X-band still kills gain and pulls the frequency response south, but more than you've ever seen before. In short, parasitics can ruin your design.

To start this discussion, here's a video of Liam Devlin (of PRFI) being interviewed by Helen Duncan, discussing the need for packaging MMICs and the issues that crop up at millimeter-wave frequencies.  He talks about over-molded plastic QFN packages versus the advantages of air-cavity plastic QFNs.  He shows a custom laminate package that includes three MMICs and two small filters. This example illustrates how PCB cutouts are used to reduce RF wirebond height differences (and therefore the wires are shorter), to minimize parasitic inductance. He concludes that for best results you should co-simulate a MMIC design with its wire-bond interface, the MMIC package and its interface to a representative printed circuit board.  Note the 2020 social distancing in the video. Stay safe everyone!

Liam Devlin of PRFI talks about millimeter-wave packaging

Below we'll add some millimeter-wave packaging topics, which we intend to fill in with more content soon.

What is you are trying to use a COTS MMIC? then you don't have access to the MMIC design to co-simulate it. How do you use the manufactuerr's S-parameters (measured on-wafer with a "probe-tip" calibration?) How do you account for the wirebond interface in this case? That is a topic for another day.

Wirebonds at millimeterwave

Flip-chip at millimeterwave

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Author : Unknown Editor

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