Cirrus Logic Inc. is an American fabless semiconductor company headquartered in Austin, Texas, that specializes in analog, mixed-signal, and audio DSP integrated circuits. Suhas Patil founded the company as "Patil Systems, Inc." in Salt Lake City in 1981; it adopted the name "Cirrus Logic" when it relocated to Silicon Valley in 1984, and moved its headquarters to Austin in 2000.

The company currently designs audio codecs, smart amplifiers, haptic drivers, and power-conversion ICs used in smartphones, laptops, tablets, digital headsets, home-theater receivers, automotive infotainment systems, and smart speakers. Apple Inc. has been the dominant customer, accounting for 89% of revenue in fiscal year 2025. In the 1990s the company also produced PC graphics chips, supplying low-cost SVGA accelerators before exiting that market in 1998. Cirrus Logic holds more than 3,900 patents issued and pending.

History

thumb|Cirrus Logic logo as of 1998

Patil Systems, Inc. was founded in Salt Lake City, Utah, in 1981 by Suhas Patil, a computer scientist who held a doctorate from MIT and had taught computer science at the University of Utah. His research had produced the Storage/Logic Array (S/LA) method of silicon compilation, an automated approach to integrated-circuit layout that became the company's technical basis; Patil Systems initially applied it to microchip-level controllers for computer hard disk drives. In 1983 the company was reorganized by Patil, Kamran Elahian, and venture capitalist Fred Nazem, whose firm Nazem and Company provided the initial financing round.

Michael Hackworth, formerly a senior vice-president at Signetics, joined Patil Systems in 1984 after Patil contacted him for help with management and marketing. Hackworth held the CEO position until February 1999. Cirrus Logic completed its initial public offering on the Nasdaq exchange in 1989 (ticker: CRUS).

thumb|left|alt=Cirrus Logic CS4297 AC'97 audio codec in TQFP package, labeled CrystalClear SoundFusion|CS4297 "CrystalClear SoundFusion" AC'97 audio codec, a product of the Crystal Semiconductor lineage

Cirrus Logic acquired Crystal Semiconductor, a supplier of analog and mixed-signal converter ICs, in 1991, and Acumos Inc. in 1992. Through the early 1990s the company expanded into PC graphics chips, audio converters, and magnetic-storage products. In 1994 Cirrus entered a joint manufacturing venture with IBM at MiCRUS, and in 1995 agreed to a $600 million joint manufacturing arrangement with AT&T Microelectronics.

David D. French joined as president and COO in June 1998 and was named CEO in February 1999. Under French, the company exited the PC graphics business and repositioned as a supplier of analog and digital-processing chips for consumer electronics. In 1999 Cirrus acquired AudioLogic, adding PWM, multi-bit converter, and DSP technology, and acquired Peak Audio in 2000, gaining ownership of the CobraNet distributed-audio networking technology. The company announced in April 2000 that it had completed moving its headquarters to Austin, Texas, where Crystal Semiconductor had been based since its founding. In 2001 Cirrus announced its exit from magnetic-storage chips and acquired several start-ups in video decoding, video encoding, and networked digital audio; it closed the resulting wireless-networking operations in 2003.

In June 2005, Cirrus Logic sold its video-products operation to an investment firm, creating the privately held Magnum Semiconductor. After French resigned in March 2007, Jason Rhode, formerly vice president and general manager of the Mixed Signal Audio Division, became president and CEO in May 2007. Rhode oversaw two acquisitions that year: Apex Microtechnology, a provider of high-power ICs for industrial and aerospace markets, and audio-chip company Tripath, acquired from bankruptcy. Cirrus divested the Apex Microtechnology hybrid-product line in Tucson in 2012. In 2007, the sixth-generation iPod Classic was the first Apple portable media player confirmed by industry teardown analysis to use a Cirrus Logic audio codec, replacing Wolfson Microelectronics components used in earlier iPod models. Wolfson confirmed in March 2008 that it had not been selected for Apple's next-generation iPods; analysts attributed the audio codec socket to Cirrus Logic.

In 2014, Cirrus Logic acquired Wolfson Microelectronics, a semiconductor company headquartered in Edinburgh, Scotland, founded in 1984, for approximately $467 million. A 2018 agreement with Apple Inc. to supply active noise-reduction chips for AirPods formalized a partnership that had grown to dominate Cirrus Logic's revenue. In 2021, the company acquired Lion Semiconductor, a developer of power-conversion ICs, for $335 million, expanding into USB Power Delivery and battery-charging ICs. Also in 2021, John Forsyth succeeded Rhode as president and CEO; Forsyth had been named company president in January 2020 and formally assumed the CEO role on January 1, 2021, with Rhode continuing as an executive fellow.

Ambient Technologies

thumb|Ambient MD4450C modem chip. Earlier models (CL-MD4450C) carried the Cirrus Logic brand.

Following a change in strategic focus, Cirrus Logic spun off its PC-modem business unit as Ambient Technologies in January 1999. Intel acquired Ambient Technologies in early 2000 and renamed it its "Modem Silicon Operation" division.

Products

Cirrus Logic organizes its current semiconductor portfolio around four product families.

Audio codecs convert between analog audio signals and digital data. The company's stereo codecs and multi-channel audio hubs are used in smartphones, laptops, digital headsets, and home-theater receivers. Smart-codec variants integrate a DSP that handles voice wake-word detection and active noise cancellation in software, reducing demands on a host processor.

Haptic drivers (the CS40L series) generate precisely shaped waveforms for piezoelectric and eccentric-rotating-mass actuators, providing controlled tactile feedback in smartphones and wearables.

Power-conversion ICs (derived from the 2021 Lion Semiconductor acquisition) implement USB Power Delivery controller and charger functions, including high-efficiency battery charging and fast-charging protocols used in smartphones and laptop power adapters. The Cirrus GD5422 (1992), for example, supported hardware acceleration for both 8-bit color and 16-bit color, and was among the lowest-priced SVGA controllers to offer both.

By the mid-1990s, after PCs had adopted the PCI bus, Cirrus had lost ground to S3 and Trident, a shift associated with poor investments and slow product development that forced restructuring charges and workforce reductions in 1996 and 1997. Development of the GD5470 "Mondello" desktop GPU, promised for release by the end of 1994, was cancelled; the GD5464 with Rambus DRAM was completed instead.

The company's final graphics products, the GD546x "Laguna" series of PCI/AGP 3D accelerators, used Rambus RDRAM and introduced a tiled-memory architecture. The feature set (perspective-correct texture mapping, bilinear filtering, single-pass lighting, Gouraud shading, and alpha blending) was competitive but arrived as faster rivals reached the market. In 1998, Cirrus announced it would divest its graphics, modems, and advanced-systems businesses.

Cirrus Logic graphic chips remain in use in hardware emulators. Both QEMU and Bochs emulate the Cirrus CLGD 5446 PCI VGA card; Bochs additionally emulates the CL-GD5430 ISA card.

Graphics chipsets

thumb|[[3DLabs Oxygen 402 PCI card with CL-GD5429]]

thumb|CL-GD5464 "Laguna 3D" graphics card

thumb|upright|CL-GD5480 graphics chip

Desktop

upright|thumb|CL-GD5462 graphics chip

  • CL-GD410 + CL-GD420 – ISA SVGA chipset; Video Seven VEGA VGA (1987)
  • CL-GD510 + CL-GD520 – ISA SVGA "Eagle II" chipset; 100% CGA emulation (1988)
  • CL-GD5320 – ISA SVGA chipset (1990)
  • CL-GD5401 – ISA SVGA chipset (Acumos VGA / AVGA1)
  • CL-GD5402 – ISA SVGA chipset (Acumos VGA / AVGA2)
  • CL-GD5410 – ISA SVGA chipset; integrated RAMDAC and clock generators (1991)
  • CL-GD5420 – ISA SVGA; integrated 15-bit RAMDAC + PLL; 1 MB
  • CL-GD5421 – ISA SVGA; 15/16-bit RAMDAC + PLL; 1 MB
  • CL-GD5422 – Enhanced CL-GD5420 with 32-bit internal memory interface and 15/16/24-bit RAMDAC; 1280×1024 interlaced maximum resolution
  • CL-GD5424 – VLB variant of the CL-GD5422
  • CL-GD5425 – True-color VGA controller with TV output
  • CL-GD5426 – Hardware BitBLT engine; ISA and VLB; up to 2 MB
  • CL-GD5428 – Enhanced CL-GD5426 with faster BitBLT engine
  • CL-GD5429 – Enhanced CL-GD5428 with higher memory clock and memory-mapped I/O
  • CL-GD5430 – Similar to CL-GD5429 with 32-bit host interface (CL-GD543x core)
  • CL-GD5434 – PCI Alpine family; 64-bit internal memory interface; up to 2 MB (1994)
  • CL-GD5436 – Optimized CL-GD5434
  • CL-GD5440 – CL-GD5430 with motion-video acceleration (CL-GD54M40 has integrated filters)
  • CL-GD5446 – 64-bit Alpine VisualMedia accelerator; 2D only with motion-video acceleration
  • CL-GD546X – Laguna Family VisualMedia Accelerators for 2D, 3D, and video; BitBLT engine, video windows, and 64×64 hardware cursor; single-channel RDRAM providing up to bandwidth.
  • CL-GD5462 – No 3D acceleration
  • CL-GD5464 – Hardware 3D acceleration (PCI)
  • CL-GD5465 – AGP support
  • CL-GD5480 – 64-bit Alpine accelerator with 100 MHz SGRAM and MPEG-2 video acceleration

Mobile

thumb|upright|CL-GD6235 mobile graphics chip

  • CL-GD610 + 620 (1989)
  • CL-GD6420/6440 – Used in some laptops; similar to CL-GD5410/AVGA2
  • CL-GD6205/6215/6225/6235 – Compatible with CL-GD5420
  • CL-GD7541/7542/7543/7548 – Compatible with CL-GD5428/5430 series

See also

  • Graphics card
  • Graphics processing unit
  • Wolfson Microelectronics

References

  • – Cirrus Logic spinoff of PC-modem IC division, later acquired by Intel