International Rectifier
International Rectifier was a United States semiconductor company known for power-management devices, power MOSFETs, and integrated power systems.
Last updated August 31, 2026
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Overview
International Rectifier was an American power-semiconductor and power-management company founded in Los Angeles in 1947 by Leon Lidow and his son, Eric Lidow. The company began by commercializing specialized selenium-rectifier manufacturing processes. Rectifiers convert alternating current into direct current, making them important components in industrial equipment, military electronics, and the expanding postwar electrical market. International Rectifier subsequently moved into semiconductor rectifiers and became one of the best-known specialist suppliers of power devices. The company achieved several notable technology milestones. It commercialized germanium rectifiers in the 1950s and silicon rectifiers by the end of that decade. Its later portfolio included discrete power devices, power transistors, power MOSFETs, intelligent power integrated circuits, voltage regulators, motor-control products, and advanced packaging technologies. The 1979 introduction of the HEXFET power MOSFET family became particularly important to the company’s identity and long-term competitive position. International Rectifier also developed FlipFET wafer-level packaging, DirectFET packaging, iMOTION motor-control products, SmartRectifier ICs, SupIRBuck integrated regulators, gallium-nitride power devices, PowIRstage products, CHiL digital controllers, and automotive-oriented power components. International Rectifier was not always focused exclusively on semiconductors. During the 1960s, management pursued diversification in an effort to reduce exposure to the cyclical nature of semiconductor earnings. This strategy led to the creation of Rachelle Laboratories, a biochemical and pharmaceutical subsidiary. Rachelle became involved in generic doxycycline production through an Italian subsidiary. Pfizer sued over alleged infringement of a patent covering the drug’s manufacturing process. After years of litigation, International Rectifier suffered a major legal setback in 1983 and reached a settlement that involved surrendering its pharmaceutical, animal-health, feed-additive, and related biochemical assets. The episode ended the company’s diversification effort and pushed it back toward power semiconductors and power-management technologies. International Rectifier built a vertically integrated manufacturing and engineering network, with wafer fabrication, assembly, testing, high-reliability packaging, and research operations in North America, Europe, and Mexico. Its products served power supplies and electronic systems used in computers, servers, networking equipment, telecommunications, lighting, automobiles, satellites, aircraft, and defense systems. The company was publicly traded in the United States for much of its independent history. In August 2014, Infineon Technologies agreed to acquire International Rectifier in an all-cash transaction valued at approximately $3 billion. The acquisition closed on January 13, 2015. International Rectifier then ceased to operate as an independent public company and became part of Infineon. Infineon continued using the International Rectifier name for certain product families, technologies, facilities, and high-reliability offerings, while integrating the company’s portfolio into its broader semiconductor business. The historical International Rectifier brand is therefore best understood as a former independent corporate semiconductor brand whose power-device technologies remain represented within Infineon’s product organization.
History
International Rectifier was established on August 9, 1947, in Los Angeles, California, by Leon Lidow and Eric Lidow. The founders had backgrounds in electrical engineering and earlier photoelectric and selenium-related work. The new company initially employed a small staff and concentrated on manufacturing selenium rectifiers, components used to convert AC power to DC power in industrial and military equipment. The company expanded from selenium into semiconductor rectification. It commercialized germanium rectifiers in 1954 and silicon rectifiers in 1959, helping establish a technical foundation in power electronics. International Rectifier went public on the New York Stock Exchange in September 1958 under the symbol IRF. During the 1960s, the company pursued diversification beyond semiconductors, including the formation of Rachelle Laboratories and related biochemical and pharmaceutical activities. The diversification effort created serious legal and financial pressure. Rachelle Laboratories and an Italian affiliate became involved in producing generic doxycycline, a drug marketed by Pfizer as Vibramycin. Pfizer alleged that International Rectifier’s process infringed its patent. Although International Rectifier initially obtained a favorable district-court ruling on part of the dispute, that result was overturned on appeal. In 1983, the company faced a final judgment reported at approximately $55.8 million. It settled by transferring or surrendering related pharmaceutical, animal-health, feed-additive, and biochemical assets. The dispute effectively ended the diversification strategy and returned International Rectifier’s attention to power semiconductors. International Rectifier’s later history was defined by power-device innovation. In 1974, it introduced power and Darlington transistors using glass passivation. In 1979, it launched the HEXFET family, an early hexagonal power-MOSFET architecture that became one of its most recognized technologies. Intelligent power ICs followed in 1983. The company later developed wafer-level and high-density packaging technologies, including FlipFET in 2000 and DirectFET in 2002. During the 2000s and early 2010s, its portfolio broadened to include motor-control platforms, integrated voltage regulators, digital power controllers, gallium-nitride devices, automotive components, and other integrated power products. The company operated an international manufacturing footprint. Its activities included wafer fabrication in the United States and Europe, assembly and testing in Mexico, and high-reliability packaging for military, aerospace, and space applications. Some facilities and product lines were retained, sold, or reorganized after the company was acquired. Infineon Technologies announced its agreement to purchase International Rectifier in August 2014 for approximately $3 billion in cash. The transaction closed on January 13, 2015. International Rectifier ceased to be an independent company and became part of Infineon. The International Rectifier name and technologies continued in selected Infineon product, facility, and high-reliability contexts, but the standalone corporate brand and NYSE listing ended.
- 2015
Acquisition completed
[1]International Rectifier became part of Infineon Technologies on January 13, ending its independent corporate status.
- 2014
Infineon acquisition announced
[1]Infineon Technologies announced an agreement to acquire International Rectifier for approximately $3 billion in cash.
- 2008
Gallium-nitride power platform introduced
[1]International Rectifier expanded into gallium-nitride power devices.
- 2002
DirectFET introduced
[1]The company introduced DirectFET, a proprietary MOSFET packaging approach intended to improve thermal and electrical performance.
- 1983
Pfizer litigation concluded
[1]A patent dispute over generic doxycycline resulted in a major judgment and the exit from the company’s pharmaceutical diversification.
- 1979
HEXFET power MOSFET introduced
[1]International Rectifier introduced its hexagonal power MOSFET architecture marketed as HEXFET.
- 1959
Silicon rectifier introduced
[1]The company introduced a silicon-based rectifier, extending its semiconductor power-device portfolio.
- 1958
Public listing
[1]International Rectifier listed on the New York Stock Exchange under the symbol IRF.
- 1954
Germanium rectifiers commercialized
[1]The company commercialized germanium rectifiers for power-conversion applications.
- 1947
Company founded in Los Angeles
[1]Leon Lidow and Eric Lidow founded International Rectifier to develop and manufacture rectification technologies.
Products and positioning
A specialist power-semiconductor supplier positioned around efficient power conversion, thermal performance, integrated power management, and high-reliability components for computing, automotive, industrial, communications, aerospace, and defense applications.
Power MOSFETs · 1979
HEXFET
HEXFET was International Rectifier’s best-known power-MOSFET technology family. Introduced in 1979, it used a hexagonal cell structure and was developed for efficient switching and power conversion. The technology became associated with applications such as computer power supplies, industrial controls, automotive electronics, and communications equipment.
MOSFET packaging · 2002
DirectFET
DirectFET was a proprietary packaging technology introduced in 2002. It was designed to reduce thermal and electrical limitations associated with conventional packages, supporting higher-density power conversion in consumer electronics, computing, and communications equipment.
Motor-control systems · 2003
iMOTION
iMOTION was an integrated design and control platform for motor applications. It combined power-stage and control functions to simplify the development of motor drives and support applications requiring compact, efficient, electronically controlled motors.
Power-management ICs · 2006
SmartRectifier
SmartRectifier ICs were introduced for AC/DC power-conversion applications. They extended traditional rectification with integrated control and sensing functions intended to improve efficiency and system performance in power supplies.
Integrated voltage regulators · 2007
SupIRBuck
SupIRBuck products integrated key elements of a voltage-regulation power stage into compact devices. They were intended for space-constrained computing, communications, and consumer-electronics designs requiring efficient point-of-load power conversion.
Gallium-nitride semiconductors · 2008
GaN power devices
International Rectifier introduced a gallium-nitride power-device platform in 2008. The technology targeted high-frequency and high-efficiency power conversion, complementing the company’s silicon MOSFET and power-IC offerings.
High-reliability power components
IR HiRel products
IR HiRel represented International Rectifier’s high-reliability product activity for military, aerospace, and space systems. Offerings included radiation-hardened and screened power components and modules designed for demanding qualification and reliability requirements.
Controversies
1983
Pfizer doxycycline patent litigation
Pfizer pursued International Rectifier and its Rachelle Laboratories operations over an alleged infringement involving a manufacturing process for generic doxycycline. The dispute ultimately produced a reported $55.8 million judgment and led International Rectifier to surrender or divest its pharmaceutical, animal-health, feed-additive, and related biochemical assets.
Brand decisions
2014
Agreement to be acquired by InfineonM&ABackground
International Rectifier and Infineon operated in complementary power-semiconductor markets, with potential benefits from combining product portfolios and manufacturing capabilities.
Action taken
Infineon agreed to acquire International Rectifier for approximately $3 billion in cash.
Aftermath
The transaction closed on January 13, 2015, and International Rectifier became part of Infineon Technologies.
announced transaction value. $3 billion (2014 announcement)
1979
Launch of HEXFET power MOSFETsProduct launchBackground
Demand was growing for more efficient and compact semiconductor switching devices in electronic power systems.
Action taken
International Rectifier introduced its hexagonal power MOSFET technology under the HEXFET name.
Aftermath
HEXFET became a central part of the company’s technology identity and supported its renewed focus on power conversion.
1960
Diversification into pharmaceuticals and biochemical productsStrategyBackground
Management sought to reduce the company’s exposure to cyclical semiconductor earnings by applying chemical-processing capabilities outside the core semiconductor business.
Action taken
International Rectifier established Rachelle Laboratories and pursued generic antibiotic and animal-health activities.
Aftermath
The strategy ended after the Pfizer litigation and the associated asset surrender, causing the company to refocus on power semiconductors and power-management products.
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