From EE Times:

Hans Camenzind, the Swiss emigre analog guru who invented one of the most successful circuits in electronics history and introduced the concept of phase-locked loop to IC design, passed away in his sleep at the age of 78. The news was reported today (Aug. 15) by Sergio Franco, an emeritus professor of electrical engineering at San Francisco State University in an email.

Camenzind came to the United States in 1960 and worked for several years at some of the storied names of the newly developing semiconductor industry: Transitron, Tyco Semiconductor, and Signetics.

In 1971 he joined the ranks of entrepreneurs by founding InterDesign, a company specializing in semi-custom integrated circuit design. It was there, working under a contract with Signetics, that he invented the 555 timer.  Signetics commercialized the device in 1972, and it went on to become one of the most successful in the industry’s history. The device, used in oscillator, pulse-generation and other applications, is still widely used today. Versions of the device have been or are still made by dozens of major semiconductor vendors, including Texas Instruments, Intersil, Maxim, Avago, Exar, Fairchild, NXP and STMicroelectronics.

Camenzind also introduced the idea of phase-locked loop to design and invented the first class D amplifier.