Gallium Arsenide, GaAs, technology has come a long way since the first microprocessor family was introduced by Camarillo, California-based Vitesse Semiconductor Corp in an agreement with Advanced Micro Devices in September 1986. Since then Vitesse has negotiated agreements with Santa Clara-based VLSI Technology Inc to develop a GaAs standard cell library for its integrated circuit design software; with E-Systems Inc of Dallas to exploit Vitesse’s proprietary digital GaAs semiconductor technology in present and feture programmes and with Ford Microelectronics Inc for an alternate sourcing agreement for foundry production of custom large-scale GaAs integrated circuits. The original microprocessor range, known as the 29G00 family, features the 29G01 4-bit CPU slice, the 29G02 carry look-ahead generator and the 29G01A 12 bit sequencer and is fully compatible with the AMD 2900 bit-slice microprocessor family. Matured But, now that the technology has matured to the point where it satisfies the technical and commercial requirements of scientific and engineering products, Vitesse – founded in 1984 to design, manufacture and market GaAs large scale integration products for a wide range of defence and commercial applications – has announced two new families of digital, high performance, large scale gate array circuits built in GaAs. The VSC1500 and 4500 gate arrays and the VSC422T RAM both comprise ASIC and memory products. As with the bit-slice VSC29G00 logic family, they feature high transistor switching speeds, low power dissipation, full military temperature range – that’s -55 to +125 `C radiation hardness, and it is claimed, the high levels of integration. The VSC1500 structured cell array offers a combination of ultra high speed/moderate power and high speed/very low power cells and the VSC4500 array, a high density high speed/very low power cell. The VSC1500 structured cell array is tailored for telecommunication fibre optic multiplexer de-multiplexer applications, for high speed backplanes in computers, as well as applications in testers and instrumentation. It has ECL inputs and outputs which handle parallel data signals compatible with 100K and 10K ECL signal levels and is tailored to transmit and receive data at 1.5GHz. The VSC4500 gate array can accept or output signals at 1GHz and typically dissipates 2W to 3W. Designed to be widely used to replace CMOS and ECL arrays, it interfaces with TTL and ECL signal levels and power supplies and has 4,500 internal gates with the capability of 120 input-output lines. The RAM product, with 4nS access time, is organised as 256 by 4 bits with TTL levels off chip. Vitesse claims it is twice as fast as pin compatible products made in Silicon and says this makes it ideal for use in cache memory, signal processing, and video applications where access time is the critical parameter. The 422T is pin compatible with industry standard 93422 and 122 Silicon products. At present the 29G00 bit slice family is being used for digital signal processing, high resolution computer graphics, real-time processing, high speed controllers and so on. The bit slice products are priced from $20 to $90 each in quantities of 100 and are available in production quantities from factory or distribution stock. The 422T RAM is priced at $70 each in quantities of 1,000. It is available in sample quantities, and will be available in production quantities in early 1988. Macro libraries are currently available for Daisy or Mentor design platforms. In its venture with VLSI, Vitesse will develop the library while VLSI provides its technical information and assistance for the porting. Vitesse, which will use VLSI’s design tools within the company, expects the library to be available by the year end. The pair plan joint marketing of the use of VLSI’s tools to design GaAs products. Lou Tomasetta, president of Vitesse, believes that this will give engineers who want to design with leading-edge technology, access to extensive hardware and software design tools for the first time. Tomasetta reckons the performance advantage
s of GaAs have made the technology attractive to the military for use in satellites, radar and other applications in which ultra-fast speeds are important. He adds that because of Vitesse’s competitive pricing, commercial customers have become more interested in GaAs circuits for fibre optic communications, test instrumentation and high-speed computers. He said the agreement would enable Vitesse to extend its technology via VLSI’s worldwide network of installed design systems. According to Douglas Fairbairn, vice president and general manager of VLSI’s ASIC division, the idea behind the get together is to make it possible for designers to use the same set of design software tools to develop ICs in Silicon or GaAs. Fairbairn reckons this will provide VLSI’s software design tool users with two complementary, rather than conflicting, technologies. As for the agreement with Ford Micro, the two companies see their alternate sourcing agreement as a breakthrough for new applications of GaAs, since multiple sourcing is required in most military systems and critical commercial applications. And in the deal with E-Systems, the Dallas company has the option to buy proprietary design, packaging and test technology from Vitesse. Tomasetta added that the company is investigating the insertion of GaAs technology into E-Systems future programmes. In a departure for the GaAs industry, Vitesse’s new products offer compatibility with industry standard input-output and power supplies. As for the technology that has excited Ford and E Systems, Vitesse claims that it provides performance levels three times those of equivalent Silicon products and complexities comparable to high speed Silicon ECL. MESFET This, along with the increasing demand for high speed circuits, has come at a time when Silicon devices are being squeezed to their theoretical limits. Vitesse says at the heart of its products lies a high speed, low power, proprietary enhancementdepletion MESFET transistor process which features metal self-aligned gates, aluminium interconnect, and MOS-like process steps. With this unique process technology, Vitesse claims it has become the first company to solve the problem of achieving high GaAs circuit yield with low power dissipation and high levels of integration. Until now, GaAs circuit design has been accomplished using depletion mode only. An all-depletion mode Field Effect Transistor approach requires more active elements for a typical gate, which results in a high power dissipation and makes higher circuit densities impractical. Vitesse says its new approach is designed for low power dissipation while still matching the transistor capabilities of Si.
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