Brooktree

Brooktree Corporation was an American semiconductor company established in San Diego in 1983 by Henry Sour Katzenstein to commercialize a high-speed architecture for digital-to-analog conversion. At the time, computer graphics systems commonly relied on several discrete components to translate digital pixel data into the analog red, green, and blue signals required by monitors. Existing designs were constrained by switching speed, output noise, and the difficulty of driving increasingly high-resolution displays. Brooktree's approach used current-driven rather than conventional voltage-driven switching. By maintaining continuously active current sources and varying the output current, the design could switch more rapidly and reduce certain forms of switching noise, although the chips consumed substantial power and generated considerable heat. The company's first major commercial product was a videoDAC introduced in 1985. Operating at approximately 75 MHz, it was substantially faster than many competing converters of the period and was designed to support displays as wide as 2,048 pixels at 60 frames per second. Commercial-scale production followed later in the decade as high-resolution workstation monitors became more common. Brooktree's components gained adoption among workstation and computer manufacturers, with reported customers including Apple, Sun Microsystems, Toshiba, and IBM. The company competed with established semiconductor suppliers such as AMD, Analog Devices, and Texas Instruments. Brooktree subsequently extended the architecture into RAMDACs, which combined digital-to-analog conversion with writable color lookup memory. Unlike fixed lookup-table implementations, RAMDACs allowed software to redefine the mapping between stored pixel values and RGB output levels. This flexibility made them useful in graphics systems that needed programmable palettes and higher color depth. The market eventually moved toward integrating these functions with graphics-controller logic on larger, more highly integrated chips, weakening demand for Brooktree's standalone converter products. During the early 1990s, Brooktree redirected much of its attention toward video capture and television-decoder silicon. The Bt848 accepted an input from a radio-frequency or video receiver and generated a digital signal suitable for compression and storage. It became widely used in personal-computer TV-tuner and video-capture boards, including products associated with Hauppauge Computer Works. The Bt878 expanded the design with audio digitization and decoding capabilities, including support for FM radio in relevant implementations. By combining more of the television-receiver functions in one device, the chip reduced the component count of complete decoder systems and could sample audio at 8-bit or 16-bit resolution at approximately 44.8 kHz. Rockwell acquired Brooktree's semiconductor business in 1996. Rockwell's semiconductor operations were later separated and reorganized as Conexant in 1998, so subsequent products derived from the Brooktree line appeared under Conexant branding rather than as independent Brooktree products. The final identifiable descendant was the Fusion 878A, which added MPEG-2 decoding and support for ATSC digital television. Brooktree's original standalone DAC business was ultimately displaced by the integration of display functions into graphics processors and by the industry's transition from analog monitor interfaces to digital display standards. Its video-capture technology nevertheless influenced a generation of inexpensive TV-tuner, capture-card, and early digital-video products.

Brooktree emerged from Henry Sour Katzenstein's work on a faster method for converting digital graphics data into analog monitor signals. In the early 1980s, graphics adapters generally used separate color-mapping, amplification, and digital-to-analog components. Their performance was limited by the speed at which output circuitry could switch while maintaining adequate drive levels, and switching activity could introduce noise into the system. Katzenstein's proposed solution controlled current rather than voltage. The design combined positive and negative current sources so that the circuitry remained continuously energized while the output level changed. This enabled much faster operation, though the constant current draw caused high heat dissipation. Katzenstein formed Brooktree in 1983 using venture funding. The company named itself after a street associated with his former residence in San Diego. Its first commercial videoDAC reached the market in 1985. With an operating speed of roughly 75 MHz, the device was several times faster than many contemporary alternatives and could support very wide, high-frame-rate displays. Production volume increased later in the decade, when workstation manufacturers began deploying monitors with resolutions that made earlier converter architectures less suitable. Brooktree gained business from major computer and workstation companies and competed with larger analog and mixed-signal semiconductor vendors. The company next developed RAMDAC products. These devices added writable memory to the conversion process, allowing software to change the color lookup table rather than relying on a fixed mapping. This was valuable in graphics applications that used programmable palettes. The advantage of standalone RAMDACs diminished as semiconductor manufacturing improved and graphics suppliers integrated lookup tables, converters, and controller logic into more comprehensive graphics chips. Brooktree therefore began looking beyond the traditional display-DAC market. Its principal second act was video capture. The Bt848, introduced in the early 1990s, digitized signals received from television or radio-frequency hardware so that a computer could compress, store, and process them. The chip became a common component in PC TV-tuner and capture boards. The Bt878 added audio conversion and decoding functions, including capabilities relevant to FM radio, and reduced the number of separate devices required in a television-decoder design. Some variants also supported teletext capture for European applications. Rockwell acquired Brooktree in 1996. The technology continued within Rockwell's semiconductor activities and later under Conexant, created through the 1998 reorganization or spinout of those operations. The Fusion 878A represented the final major continuation of the product family described in the reference material. It added MPEG-2 decoding and ATSC support, using the existing digital-audio connections in a way that allowed them to serve the digital television input. This helped bridge the transition from analog television capture to digital broadcast reception. Brooktree ceased to operate as an independent brand after the acquisition. Its original videoDAC category was weakened by graphics-chip integration and the adoption of digital monitor interfaces, while its later capture products became part of successor-company product portfolios. The company is historically significant as an early supplier of high-speed display-conversion ICs and as a contributor to the affordable PC video-capture ecosystem of the 1990s.

• 1998

  Rockwell semiconductor operations become Conexant

  [1]Brooktreeen.wikipedia.org

  The successor organization continued Brooktree-derived video products under the Conexant identity.

• 1996

  Rockwell acquisition

  [1]Brooktreeen.wikipedia.org

  Rockwell acquired Brooktree and absorbed its semiconductor technology and product lines.

• 1990

  Brooktree enters video capture

  [1]Brooktreeen.wikipedia.org

  The company introduced the Bt848 for digitizing television and related video signals in computer capture systems.

• 1988

  Mass production expands

  [1]Brooktreeen.wikipedia.org

  Production increased as high-resolution computer monitors became commercially relevant, supporting broader adoption of Brooktree's display-conversion chips.

• 1985

  First videoDAC reaches the market

  [1]Brooktreeen.wikipedia.org

  Brooktree launched a roughly 75 MHz videoDAC designed for high-resolution workstation displays.

• 1983

  Brooktree is founded

  [1]Brooktreeen.wikipedia.org

  Katzenstein established Brooktree in San Diego with venture funding to commercialize the new converter architecture.

• 1981

  Katzenstein develops the current-driven DAC concept

  [1]Brooktreeen.wikipedia.org

  Henry Sour Katzenstein developed the underlying approach for a high-speed digital-to-analog converter based on current control rather than conventional voltage switching.

A specialist semiconductor supplier focused first on high-speed display conversion for workstations and later on highly integrated video-capture and television-decoding silicon.

• Display digital-to-analog converter · 1985

  VideoDAC

  Brooktree's early videoDAC was a high-speed converter for workstation and computer-graphics displays. Its current-driven architecture enabled substantially faster operation than many voltage-switched designs of the early 1980s. The device was intended to transform digital color information into analog RGB monitor signals and was promoted for very high horizontal resolutions, including displays up to approximately 2,048 pixels wide at 60 frames per second.

• Programmable graphics digital-to-analog converter

  RAMDAC

  Brooktree RAMDACs combined high-speed digital-to-analog conversion with writable color lookup memory. This allowed graphics software to redefine how stored pixel values were translated into RGB output values, supporting programmable palettes and more flexible workstation graphics. The category later declined as graphics manufacturers integrated comparable functions with display controllers and other logic on single chips.

• Video-capture controller · 1990

  Bt848

  The Bt848 digitized incoming television or receiver signals and supplied a digital stream that a computer could compress, store, and process. It became a widely used component in PC TV-tuner and video-capture boards during the 1990s. Its adoption helped make computer-based television reception and low-cost video recording more accessible through third-party hardware.

• Audio/video capture and television decoder

  Bt878

  The Bt878 developed the Bt848 concept by adding audio digitization and decoding capabilities. Depending on the implementation, it supported television audio and FM-radio-related functions while reducing the number of chips required in a complete decoder system. Audio could be converted at 8-bit or 16-bit resolution at approximately 44.8 kHz, making the device suitable for consumer capture and tuner products.

• Digital television and video decoder

  Fusion 878A

  The Fusion 878A was the final major descendant of the Brooktree capture-chip family under Conexant. It added MPEG-2 decoding and ATSC digital-television reception to the earlier analog-oriented architecture. The design reused the earlier chip's digital-audio connections as ATSC inputs, allowing reception of digital broadcast video and audio without discarding the interface assumptions of the preceding generation.

• 1996

  Sale to RockwellM&A

  Background

  Brooktree was operating in a consolidating semiconductor market while transitioning from standalone display components to video-capture silicon.

  Action taken

  Rockwell acquired Brooktree and incorporated its technology into Rockwell's semiconductor activities.

  Aftermath

  The independent Brooktree brand disappeared, while related products continued through Rockwell's successor semiconductor business and later Conexant.

  Source

• 1990

  Diversification from display DACs into video captureStrategy

  Background

  Standalone RAMDAC demand was increasingly threatened by the integration of graphics conversion and controller functions into larger graphics chips.

  Action taken

  Brooktree introduced the Bt848 and redirected product development toward television reception, video capture, and signal digitization.

  Aftermath

  The Bt848 and Bt878 became widely used in PC TV-tuner and capture boards, giving the company a stronger presence in consumer video hardware.

  Source

• 1998

  Conexant continues the Brooktree video line with Fusion 878A[1]Brooktreeen.wikipedia.org

  Product launch · Product generation

  After Rockwell's semiconductor operations became Conexant, the Fusion 878A extended the earlier capture architecture with MPEG-2 decoding and ATSC digital-video support.

• 1996

  Rockwell acquires Brooktree[1]Brooktreeen.wikipedia.org

  M&A

  Rockwell acquired Brooktree during the company's transition toward video-capture and television-decoder products.

• 1990

  Brooktree shifts toward PC video capture with the Bt848[1]Brooktreeen.wikipedia.org

  Product launch

  The company expanded from display-conversion components into video-capture silicon capable of digitizing television or receiver signals for storage and compression.

• 1985

  Brooktree introduces a high-speed videoDAC[1]Brooktreeen.wikipedia.org

  Product launch · Product generation

  Brooktree brought its current-driven video digital-to-analog converter to market, targeting higher-resolution computer displays than many contemporary converter designs could support.

1. 1Brooktreeen.wikipedia.org