AC Microwave GmbH: Offers the LINMIC+/N microwave and RF IC design suite; mostly electromagnetics-based.
Avista Design Systems: Tools to simplify analog and RF design.
Cyme International: Offer software for various analyses, design, parameter calculation and distribution.
Designer's Guide Consulting: Provides verification and simulation services to companies involved in integrated circuit design. Includes information resource about modeling, theory and analysis, as well as a discussion forum.
EDSA Micro Corporation: Electrical power systems design software.
Hbfree: Free command line RF/microwave harmonic balance circuit simulator, for analog nonlinear circuits simulation with diode and MESFET nonlinear elements.
Infolytica: Offer electromagnetics design software for both low and high frequency applications. Products include MagNet, ElecNet and FullWave.
Schematica: Windows software for design of active filters and linear circuit simulation