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Gate Arrays |
A gate array is a matrix of uncommitted, potentially active transistors whose interconnection is "programmed" at the metal wiring level. Gate array wafers may be pre-fabricated in volume up to the final processing steps, thus achieving manufacturing economies of scale. These wafers are personalized at the metal wiring stage by applying a unique interconnection pattern that implements the customer's logic design. Therefore, development cost is low and development time is short. All of Toshiba's gate array products employ the sea-of-gates architecture. Computer software determines which transistors should be utilized for the circuit design and which transistors should be left unused so the area above can be used for signal routing. This placement and routing flexibility of sea-of-gates makes it possible to integrate large cells such as RAMs, ROMs, and multipliers on the same chip. Toshiba's gate arrays offer single gate array solutions for a wide variety of digital logic applications ranging in size from 300 to 1.9M gates.
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Cell-Based ICs |
The cell-based technique assembles pre-designed and pre-optimized cells that users select, place, and interconnect on-chip to produce the required circuit functions with optimum chip size. These cells include basic gates, as well as various memory blocks, core functions, and analog cells. Because all of the mask set needs defining, the initial engineering charge is slightly higher than for a gate array for a given gate complexity. Also, the lead-time to prototypes and production is longer than for a gate array. However, sized to fit individual design specifications, cell-based ICs leave little unused silicon area, thus giving generally lower chip cost. This makes cell-based ICs suitable for high-volume products. Toshiba's cell-based IC libraries include many specialized functions such as RAMs, ROMs, FIFOs, multipliers, adders, subtractors, barrel shifters and CPU peripherals. In addition, a wide selection of system cores such as RISC processor cores and DRAM cores are available. Cell-based ICs also provide broad mixed signal support. Among analog cells available are A/D converters, D/A converters, analog PLLs (APLLs), etc.
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Embedded Arrays |
Embedded arrays combine high-performance functions of cell-based ICs with the gate array advantage of quick turnaround. They span the gap between gate arrays and cell-based ICs in terms of costs, performance, and prototype and production turnaround. Embedded arrays use the same sea-of-gates technology as gate arrays, but allow designers to "embed" dense memory blocks and specialized functions in a gate array base by replacing part of its sea-of-gates core area with cell-based versions of the blocks.
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ASIC Process Product Brief |
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