EEsof was founded in 1983 by an entrepreneur, Charles J. ("Chuck") Abronson, and a former
Compact Software employee, Bill Childs. EEsof's first products included high-frequency circuit simulators such as Touchstone and Libra. Although the Touchstone simulator itself is obsolete, its
eponymous file format lives on. EEsof was acquired by
Hewlett-Packard in 1993 and later spun out first as part of
Agilent Technologies in 1999 and then as part of Keysight Technologies. After the merger of HP and EEsof, the EEsof products were combined with the HP simulator, Microwave Design System (MDS). HP's entry, MDS, had been introduced in 1985. It was developed in-house and comprised a linear circuit simulator with integrated schematic capture and graphical layout with back-annotation, a first for RF EDA software. MDS was offered on UNIX workstations from HP, Sun, and Apollo as well on the PC. Before the introduction of MDS, HP had a marketing relationship with EEsof and sold Touchstone software on HP platforms such as the Series 200 (but not on the PC). The marketing relationship ended after the introduction of HP's MDS product. The HP and EEsof
harmonic balance simulators also had parallel lives before the merger. HP funded an employee
Ken Kundert to do a Ph.D. at UC Berkeley. For his thesis, he developed
Spectre, the first harmonic balance prototype. Some sources argue that since Berkeley had an open policy to all of its research work, EEsof was able to learn about the project and released a product, Libra, before HP was able to commercialize it in MDS. (Libra was a play on the Latin word libra for balance or scales). However, other sources say that Libra was developed completely independently. In any case, Kundert left HP to join
Cadence Design Systems shortly after receiving his Ph.D. There he developed
Spectre and
SpectreRF. In 1997, HP acquired
Optimization Systems Associates (OSA), founded by
John Bandler in 1983. OSA thereby became part of HP EEsof. OSA’s products included HarPE and OSA90/hope, featuring the world’s then most powerful harmonic balance optimizer, as well as Empipe, Empipe3D, EmpipeExpress, and empath. OSA's optimization technology and the OSA's Empipe family became the foundation of HFSS Designer and Momentum Optimization. This integration into HP’s electromagnetic product line consolidated a paradigm shift in HP's offering of their tools—a shift from analysis to design. Longer-term plans of the acquisition included leveraging OSA technology across HP's circuit- and device-simulation product lines. On January 7, 2014, Agilent announced a plan to spin off its electronic measurement divisions, including EEsof, as a separate company, Keysight Technologies. In 2019, Keysight started to phase out the EEsof brand in favor of their new
PathWave Design branded
TestOps toolchain, although the old brand is still used in some places. ==Products==