There are some good uses for ports with an explicit (-) ground reference. Using them for SMD elements, where a device is included as 1-port with (+) on one pad and (-) on the other pad, is not a good idea in most cases. Used in the wrong context, you can get totally unexpected results from  differential ports. You really need to understand what these ports physically mean for your model.

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Semiconductor foundry IHP has licensed Inductor Toolkit for ADS, and now provides this automated inductor synthesis solution to their foundry customers at no cost. Based on target inductance and target frequency, the software will find the inductor geometry with best performance (highest Q factor).

Available layouts include IHP’s octagon shaped with/without center tap. Additional inductor layouts (different shapes, stacked metal, ground shield, localized backside etching) are available as a payed upgrade.

https://muehlhaus.com/products/rfic-inductor-toolkit-for-ads

IHP customers can download Inductor Toolkit PDK for SG25H, SGB25 and SG13 from the IHP designkit server. ADS2012.08 or later is required (not included).