While at Stanford, Rhines co-invented the magnesium-doped
gallium nitride blue
light-emitting diode, for which he, Herb Maruska and David Stevenson were awarded a U.S.
patent in 1974.
Isamu Akasaki built directly on this gallium-nitride research and eventually won the 2014
Nobel Prize in Physics, along with
Hiroshi Amano and
Shuji Nakamura. Rhines worked at Texas Instruments (TI) from 1972 to 1993, serving as executive vice president of the semiconductor group and president of the data systems group. While at TI, Rhines supervised development of speech synthesis chips used in the
Speak & Spell; developed the first publicly available computer program (for a calculator) to calculate the
Black–Scholes value of a stock option; and supervised the creation of the
TMS320 digital signal processor. In a 1985 profile of Rhines in the
Austin American-Statesman, industry consultant Will Strauss told reporter Russell Mitchell: "He [Rhines] can claim the TMS-320 digital signal processor chip; that's the one to beat on the street right now." Rhines became CEO of Mentor Graphics in 1993, when the company's annual revenue was about $340 million. The company passed $1 billion in revenue for the first time in 2011. In 2013 Mentor Graphics announced it would begin paying a quarterly dividend, making it the only of big three
electronic design automation (EDA) companies to do so; (
Cadence Design Systems and
Synopsys are the other two). Siemens announced its $4.5 billion acquisition of Mentor Graphics on November 13, 2016; the deal closed four months later. Rhines remained as CEO of Mentor, a Siemens Business and later CEO Emeritus through 2020. Rhines joined the many-core accelerator chip company Cornami as CEO in March 2020. ==Affiliations==