Macrocell array
Encyclopedia
A macrocell array is an approach to the design and manufacture of ASIC
s. Essentially, it is a small step up from the otherwise similar gate array
, but rather than being a prefabricated array of simple logic gates, the macrocell array is a prefabricated array of higher-level logic functions such as flip-flop
s, ALU
functions, register
s, and the like. These logic functions are simply placed at regular predefined positions and manufactured on a wafer
, usually called master slice. Creation of a circuit with a specified function is accomplished by adding metal interconnects to the chips on the master slice late in the manufacturing process, allowing the function of the chip to be customised as desired.
Macrocell array master slices are usually prefabricated and stockpiled in large quantities regardless of customer orders. The fabrication according to the individual customer specifications may be finished in a shorter time compared with standard cell or full custom
design. The macrocell array approach reduces the mask
costs since fewer custom masks need to be produced. In addition manufacturing test tooling lead time and costs are reduced since the same test fixtures may be used for all macrocell array products manufactured on the same die
size.
Drawbacks are somewhat low density and performance than other approaches to ASIC design. However this style is often a viable approach for low production volumes.
Application-specific integrated circuit
An application-specific integrated circuit is an integrated circuit customized for a particular use, rather than intended for general-purpose use. For example, a chip designed solely to run a cell phone is an ASIC...
s. Essentially, it is a small step up from the otherwise similar gate array
Gate array
A gate array or uncommitted logic array is an approach to the design and manufacture of application-specific integrated circuits...
, but rather than being a prefabricated array of simple logic gates, the macrocell array is a prefabricated array of higher-level logic functions such as flip-flop
Flip-flop (electronics)
In electronics, a flip-flop or latch is a circuit that has two stable states and can be used to store state information. The circuit can be made to change state by signals applied to one or more control inputs and will have one or two outputs. It is the basic storage element in sequential logic...
s, ALU
Arithmetic logic unit
In computing, an arithmetic logic unit is a digital circuit that performs arithmetic and logical operations.The ALU is a fundamental building block of the central processing unit of a computer, and even the simplest microprocessors contain one for purposes such as maintaining timers...
functions, register
Hardware register
In digital electronics, especially computing, a hardware register stores bits of information, in a way that all the bits can be written to or read out simultaneously.The hardware registers inside a central processing unit are called processor registers....
s, and the like. These logic functions are simply placed at regular predefined positions and manufactured on a wafer
Wafer (electronics)
A wafer is a thin slice of semiconductor material, such as a silicon crystal, used in the fabrication of integrated circuits and other microdevices...
, usually called master slice. Creation of a circuit with a specified function is accomplished by adding metal interconnects to the chips on the master slice late in the manufacturing process, allowing the function of the chip to be customised as desired.
Macrocell array master slices are usually prefabricated and stockpiled in large quantities regardless of customer orders. The fabrication according to the individual customer specifications may be finished in a shorter time compared with standard cell or full custom
Full custom
Full-custom design is a methodology for designing integrated circuits by specifying the layout of each individual transistor and the interconnections between them...
design. The macrocell array approach reduces the mask
Photomask
A photomask is an opaque plate with holes or transparencies that allow light to shine through in a defined pattern. They are commonly used in photolithography.-Overview:...
costs since fewer custom masks need to be produced. In addition manufacturing test tooling lead time and costs are reduced since the same test fixtures may be used for all macrocell array products manufactured on the same die
Die (manufacturing)
A die is a specialized tool used in manufacturing industries to cut or shape material using a press. Like molds, dies are generally customized to the item they are used to create...
size.
Drawbacks are somewhat low density and performance than other approaches to ASIC design. However this style is often a viable approach for low production volumes.