Application-Specific Integrated Circuit (ASIC) is an integrated circuit custom-designed to perform a specific set of functions. An ASIC based device typically has better performance and lower cost over a similar design with standard chips. ASICs are commonly used in high-speed switches and routers. A typical device designed using standard chips typically has many individual components, and run many functions in software. A device/system based on ASIC can consolidate the function of all of those chips, and even the software, onto a single chip. The complete device or system ASIC is often reffered to as SoC - System on a Chip.

The early design of ASIC used the logic synthesis tools (such as Design Compiler) that could accept hardware description language descriptions using Verilog and VHDL and compile a high-level description into to an optimised gate level netlist brought "standard-cell" design into the fore-front. A standard-cell library consists of pre-characterized collections of logic gates that the silicon compiler uses to translate the original source into a gate level netlist. This netlist is fed into a place and route tool to create a physical layout. Routing applications then place the pre-characterized cells in a matrix fashion, and then route the connections through the matrix. The final output of the "place & route" process comprises a data-base representing the various layers and polygons in GDS-II format that represent the different mask-layers of the actual chip.

Designers can also take the "full-custom" route in implementing an ASIC, in which an individual description of each transistor occurs in building the circuit. A "full-custom" implementation may function much faster than a "standard-cell" implementation which is usually implemented quicker with less risk of errors, than the "full-custom" choice.

As feature sizes have shrunk and design tools improved over the years, the maximum complexity and functionality has increased from 5000 gates to 20 million or more. Modern ASICs often include 32-bit processors and other large building-blocks.

Designers of most complex digital ICs now utilise computer languages that describe electronics rather than code. Many organizations now sell tested functional blocks written in these languages. For example, one can purchase CPUs, ethernet or telephone interfaces.

Related Terms: Integrated Circuit (IC), System on Chip (SoC)