ASIC and FPGA
ASIC
ASIC stands for Application Specific Integrated Circuit. It is specially built for a specific
application or purpose. If compared to any other device, ASIC has improved speed. Basically,
it is an integrated circuit that’s been specified for one specific purpose and is not software
programmable to perform a wide variety of different tasks. These are widely used in
applications, including auto emission control, environmental monitoring, and personal digital
assistants. It often has an embedded CPU to manage suitable tasks.
ASIC Categories
• Full – Custom ASICs
• Semi-Custom ASICs
• Programmable ICS
•
Programmable: These are not custom made, and can be run in the data center, campus,
or in a metro Ethernet environment. It is further subdivided into two categories.
• FPGAs: These are complex and larger reconfigurable devices, which include
programming logic cells and interconnect. For Example Xilinx, Altera, QuikLogic, etc
are some of the FPGA companies
• PLDs: These are the electronic devices used to build reconfigurable circuits. For
Example- GAL ROM, PROM, EPROM, EEPROM, etc.
• Full Custom: These are custom-made from scratch for a specific application. It is a
design methodology useful for integrated circuits. There are the resistors, transistors,
digital logic, capacitors, and analog circuits are positioned in the circuit layout. For
Example Microprocessor. It takes a minimum time of 8 weeks for normal manufacturing
and is quite expensive. Features- Maximum performance, minimized area, and the
highest degree of flexibility.
• Semi-Custom: These are customized partially so that they can perform the different
functions within the area of their general application. Basically, it is an alternative to fullcustom designs. It is further subdivided into two categories:
• Gate Array Based: These have pre-defined transistors on the silicon wafer.
• Standard Cell Based: Some logic gates such as AND gates, OR gates, multiplexers,
flip-flops are pre-designed by designers by using different configurations, standardized,
and stored in the form of a library, this is known as a standard cell library. The cell area
or flexible block is made up of standard cells arranged in the form of rows, with these
flexible blocks mega cells like microcontrollers or even microprocessors are used onchip.
FPGA –
The full form of FPGA is “Field Programmable Gate Array”. It contains ten thousand to
more than a million logic gates with programmable interconnection. Programmable
interconnections are available for users or designers to perform given functions easily. Field
Programmable Gate Arrays (FPGAs) are semiconductor devices that are based around a matrix
of configurable logic blocks (CLBs) connected via programmable interconnects. FPGAs can
be reprogrammed to desired application or functionality requirements after manufacturing. An
FPGA is a regular structure of logic cells (or modules) and interconnect, which is under your
complete control. This means that you can design, program, and make changes to your circuit
whenever you wish. A typical model FPGA chip is shown in the given figure. There are I/O
blocks, which are designed and numbered according to function. For each module of logic level
composition, there are CLB’s (Configurable Logic Blocks).
CLB performs the logic operation given to the module. The inter connection between CLB and
I/O blocks are made with the help of horizontal routing channels, vertical routing channels and
PSM (Programmable Multiplexers). The number of CLB it contains only decides the
complexity of FPGA. The functionality of CLB’s and PSM are designed by VHDL or any other
hardware descriptive language. After programming, CLB and PSM are placed on chip and
connected with each other with routing channels.
Advantages
•
•
•
It requires very small time; starting from design process to functional chip.
No physical manufacturing steps are involved in it.
The only disadvantage is, it is costly than other styles.
FPGA Applications
Due to their programmable nature, FPGAs are an ideal fit for many different markets.
ASIC Prototyping, Aerospace & Defense, Automotive, Broadcast & Pro AV, Consumer
Electronics, Data Center, High Performance Computing, Data Storage, Industrial, Medical,
Security, Video & Image Processing, Wired Communications, Wireless Communications