Lj. Ristic

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Lj. Ristic
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Born1950
Nis, Yugoslavia
NationalitySerbian American
Education
  • Bachelor of Science (BS)
  • Master of Science (MS)
  • Ph.D.
Alma materUniversity of Nis
Occupation
  • Engineer
  • Scientist
  • Entrepreneur

Lj. (Ljubisa) Ristic, born 1950 in Nis, Yugoslavia, is a Serbian born Canadian-American engineer, scientist, and entrepreneur known for his contributions to semiconductor technology and devices, sensors, microelectromechanical systems (MEMS), RF systems, and optoelectronic systems.

Dr. Ristic is recognized for his pivotal role and pioneering work on development and industrialization of MEMS (Micro-Electro-Mechanical-Systems) technology, as well as the integration of CMOS and MEMS technology. He has published the first book in the world on MEMS technology. Dr. Ristic is considered as one of the top sensor experts, having made several groundbreaking inventions. He has invented three-polysilicon process for surface micromachining (3D micromachining methodology), as well as wafer-level bonding with ESD protection, both essential for sensor manufacturing. His inventions also include microprocessors with sensing capability, as well as multiple types of sensors, from MEMS accelerometers, and pressure sensors, to resonators and magnetic field sensors. Also, he is the inventor of optoelectronic systems based on fusion of laser sensing and optical laser projections. In addition, he has done significant work in the area of basic semiconductor devices such as p-n junctions, bipolar transistors, Hall devices, and MTJs (magnetic tunnel junctions). Finally, he has made significant contributions in the area of RF-integration of the front-end antenna for cellular telephones.

Education

He earned multiple degrees in electronics, including Bachelor of Science (BS), Master of Science (MS), and Ph.D. from University of Nis, Serbia, in 1975, 1982 and 1988, respectively. He also earned in 1997 an MBA in global management from the Thunderbird School of Global Management[1] in Arizona.

Career Overview

Ristic's career includes work in both industry and academia. His research has revolved around the design and fabrication of semiconductor solid-state devices and systems, encompassing sensors, microelectromechanical systems (MEMS), RF solutions, and optoelectronic systems.

During his early career at Electronics Industry Nis, he concentrated on the impact of semiconductor processing on the performance of semiconductor devices[2] and the investigation of surface effects on the breakdown voltage of p-n junctions.[3] This resulted in the development of a high-volume manufacturing process for new products with stable breakdown voltage, leading to the production of millions of reliable devices.

In 1985, Ristic relocated to Canada, joining the Faculty of Electrical Engineering at the University of Alberta, where he continued his research into sensors and MEMS technology while teaching and mentoring students in master's and Ph.D. programs. By 1989, he had achieved the rank of full professor. His work included magnetic field sensor based on bipolar transistors,[4] silicon Hall devices,[5] and the pioneering development of integrated devices for three-dimensional sensing of magnetic fields.[6][7] He also made contributions to silicon micromachining in CMOS technology.[8]

In 1990, Ristic moved to the USA and joined Motorola in Phoenix, where he led the sensor device group and played a key role in advancing and industrialization of MEMS technology. He developed innovative technologies, including three-polysilicon layer surface micromachining technology (3D micromachining methodology) and plastic packaging with electrostatic discharge protection.[9][10][11] His work also encompassed the integration of sensing technology with CMOS technology, resulting in significant intellectual property related to microprocessor and sensor integration.[12] Ristic received several awards for his contributions at Motorola, including a Distinguished Innovator, a Golden Badge, and a Silver Quill Award.

In 2000, he assumed the role of Vice President of Technology and Chief Technology Officer at Alpha Industries in Massachusetts.[13] There he focused on advancing RF technologies and creating new products for wireless, consumer, and fiber-optic applications. He pioneered the development of RF front-end multichip integrated module, which included InGaP power amplifiers, switches, and filters.[14] These components have since become standard building blocks in modern smartphones, tablets, laptops, and other consumer devices.

After his tenure at Alpha Industries, he continued to work with various startups in executive roles,[15] contributing to wide range of technological innovations including sensing solutions based on tunnel magnetoresistance technology,[16][17] MEMS-based battery solutions,[18] dynamic laser light solutions for automotive applications,[19] and the fusion of Lidar and projection technology.[20]

Impact of Lj. Ristic’s Innovations

The impact of Dr. Ristic’s innovations is multifold. His invention of MEMS accelerometer with self-testing capability together with 3D micromachining led to massive adoption of airbags in automotive industry that became a standard feature in every automobile today. These accelerometer sensors are being manufactured in hundreds of millions. 3D micromachining methodology also laid ground for high density DRAM cells and integrated RF tuning filters. His invention of microprocessor with sensing capability including seminal work on integration of MEMS and CMOS technology, have paved ground for development of smart sensors, while his work on RF integration of front-end antenna with switches and power amplifiers has enabled efficient operation of cellular telephones on multiple bands. In addition, his work on magnetic field sensors has also pushed the boundaries of knowledge and understanding of these devices. He has demonstrated that lateral bipolar transistors and Hall devices can be used for 3-dimensional magnetic field sensing. This pioneering work on 3-D magnetic field sensors has open gate for their use in cellular telephones in GPS applications. Also, his inventive design work on MTJ devices has led to industrialization of this technology and introduction of first MTJs products. Additionally, his ingenious solution for elimination of impact of surface effects on the breakdown voltage of planar p-n junction led to manufacturing of tens of millions of diode products with the predefined breakdown voltage. Furthermore, his inventions of optoelectronic systems based on the fusion of laser sensing and optical laser projections have created the path for novel applications in industrial automation, robotics, safety in automotive industry, and Physical AI.

Publications

Throughout his career, Lj. Ristic has authored more than 100 scientific papers and edited the first book on silicon micromachining technology.[21][22][23] He has also written extensively on various topics in semiconductor technology, investigating trends related to sensor fusion,[24] transceivers,[25] microprocessors,[26] and MEMS mirrors.[27][28]

References

  1. ↑ "Thunderbird School of Global Management". thunderbird.asu.edu.
  2. ↑ Lj. Ristic et al. "Stress in epitaxial silicon layer caused by CVD-SiO2 densification – influence on transistor characteristics", Proc. 23rd ETAN, Maribor, pp. I347–I354, June 1979.
  3. ↑ N. D. Stojadinovic, Lj. Dj. Ristic and B. V. Vidanovic, "New technique for fabrication of low voltage Si Zener diodes", Electronics Letters, vol. 17, no. 3, pp. 130–132, February 1981.
  4. ↑ Lj. Ristic, T. Smy and H. P. Baltes, "A lateral magnetotransistor structure with linear response to the magnetic field", IEEE Transactions on Electron Devices, vol. 36, no. 6, pp. 1076–1086, June 1989.
  5. ↑ Lj. Ristic, M. Paranjape and M. T. Doan, "2-D Magnetic field sensor based on Vertical Hall Device", Technical Digest, SSSA Workshop, Hilton Head Island, pp. 111–113, 1990.
  6. ↑ Lj. Ristic, M. Doan and M. Paranjape, "3-D magnetic field sensor as a lateral magnetotransistor in CMOS technology", Sensors and Actuators, vol. A22, pp. 770–775, 1990.
  7. ↑ Lj. Ristic and M. Paranjape, "Hall devices for multidimensional sensing of magnetic field", Sensors and Materials, vol. 5, no. 5, pp. 301–316, 1994.
  8. ↑ Lj. Ristic, "CMOS technology: a base for micromachining", Microelectronics J., vol. 20, nos. 1–2, pp. 153–169, 1989.
  9. ↑ Patent US5146389, "Differential capacitor structure and method", 1992-09-08.
  10. ↑ Ristic et al. "A capacitive type accelerometer with self-test feature based on double-pinned polysilicon structure", 7th Int. Conf. SSSA, Transducers '93, Yokohama, June 1993.
  11. ↑ Patent US5545912, "Electronic device enclosure including a conductive cap and substrate", 1996-08-13.
  12. ↑ Patent US5291607, "Microprocessor having environmental sensing capability", 1994-03-01.
  13. ↑ https://investors.skyworksinc.com › news-release-details
  14. ↑ Lj. Ristic et al. "RF module solutions for the wireless handset market – part 1: switch-filter modules", Microwave Product Digest, November 2001.
  15. ↑ Nenni, Daniel (7 July 2025). "MEMS Technology – From Fringe to Mainstream". SemiWiki. Retrieved 1 October 2026.
  16. ↑ Patent US2016084674A1, "Apparatus and Method for Magnetic Sensor Based Surface Shape Analysis", 2016-03-24.
  17. ↑ Frank, Randy (15 September 2015). "MLU Technology for Sensor Products, interview with LJ Ristic". sensortips.com.
  18. ↑ Patent US20210135271A1, "Method of fabricating porous wafer battery", 2021-05-06.
  19. ↑ Patent US20200200363A1, "Fiber-delivered laser-induced dynamic light system", 2020-06-25.
  20. ↑ Patent US12529766 B2, "LIDAR system with projection capability", 2026-01-20.
  21. ↑ Ristic, Ljubisa, ed. (1994). Sensor Technology and Devices. Boston: Artech House. ISBN 0-89006-532-2.
  22. ↑ "Book Review: "Sensor Technology and Devices", Lj. Ristic (ed.)". Measurement Science and Technology. 11 (12): 1829. December 2000. doi:10.1088/0957-0233/11/12/710.
  23. ↑ https://www.barnesandnoble.com/w/sensor-technology-and-devices-ristic-ljubisa-ristic/1124243383
  24. ↑ Ristic, Lj. (3 September 2012). "Sensor fusion and MEMS for 10-DoF solutions". EETimes.com.
  25. ↑ "Petrov Group Announces Study Of Transceiver Strategies For 3G Handsets". wirelessdesignonline.com. 6 March 2006.
  26. ↑ "Baseband processors still essential, says Petrov Group". DigiTimes. 3 May 2011.
  27. ↑ Ristic, Lj. (24 July 2023). "MEMS mirrors: The next big wave in MEMS technology". Laser Focus World.
  28. ↑ "MEMS Mirrors: The Next Big Wave in MEMS Technology". Electronic Design. 4 October 2023.

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