What differentiates FPGA from ASIC
In the world of electronics, both FPGA and ASIC hold a prominent place. Throughout the decades, both technologies have evolved and added new features that are paving the way for innovation and making products more agile and scalable.
Both technologies have different features and are best suited for different types of devices and hardware purposes. FPGAs have seen a drastic shift in the last ten years and now have become larger in terms of gate count and contain analog blocks, which was not the case years back. On the same lines, ASICs now have higher gate density and lower power consumption than five years ago.
There are many differences between FPGA and ASIC, and this piece is aimed at throwing light on these points of comparison. The motive is to pave a clear path on how to harness these disruptive technologies to design best-in-line products that are aligned with factors such as pricing, size, and power consumption, etc.
What is an FPGA?
FPGA stands for Field Programmable Gate Array. These are a type of integrated circuits that can be ‘field programmed’ to suit intended and varying purposes. What this means is that FPGAs can act as a microprocessor, or an encryption unit, or a graphic card, or all of these combined at a given time. Therefore, an FPGA working as a microprocessor can be reprogrammed to work as a graphic card in the field.
What is an ASIC?
ASIC stands for Application Specific Integrated Circuits. As the name suggests, these circuits are application-specific, designed for one sole purpose, and function in the same manner throughout their operating lives. For example, the CPU inside a smartphone is an ASIC and can function only as a CPU throughout the life of the phone. The logic function of an ASIC cannot be changed to anything else as its digital circuitry consists of permanently connected gates and flip-flops in silicon.
Points of Comparison
NRE and Configuration
NRE stands for Non-Recurring Expenses, which is a focal point for most businesses as it ensures reduction of development costs and increases profit. The NRE for ASICs is very high, whereas it is almost non-existent for FPGAs. The reason being - FPGAs are reconfigurable, and ASICs are permanent circuits.
The functionalities of an ASIC cannot be modified once they are developed, and hence with every new requirement comes the need to buy another ASIC possessing the intended functionality. FPGAs, on the other hand, can be reconfigured even when they are in use, which reduces the recurring cost of buying additional circuits to meet different needs. This very feature makes FPGAs a popular choice among individuals and fields desirous of high velocity, accelerated computing like data centers, etc.
The design flow of FPGA is very simple, which is also credited as a major reason for its low NRE and faster time-to-market. Features such as reprogrammability and flexibility make the flow very simple and understandable. ASICs, on the other hand, are application-specific and hence have a more complex design flow. Additionally, designing an ASIC requires dedicated EDA tools, which are very costly to acquire.
Despite a very high NRE cost, ASICs prove to be very cost-effective when acquired for mass production. FPGAs, on the other hand, cost more, but the fact that they almost have a non-existent NRE cost and are reprogrammable makes them more scalable, agile, cost-friendly. The reason is simple - FPGAs can be reprogrammed ‘n’ number of times to change functionalities and gives the flexibility to correct small design mistakes, which is not the case with ASICs. Even small design mistakes in ASICs cannot be fixed and require a respin to produce a new chip.
The broad spectrum of functionalities makes FPGAs more power-consuming when compared to an ASIC. ASICs are less power consuming and more suitable for battery-powered devices. Still, as a matter of fact, low power consumption comes at the cost of reduced functionality, scalability, and agility.
FPGAs have a fixed internal structure and a specific minimum size, which makes them relatively larger in size when compared to ASICs. The size of ASICs is compact because they contain exactly the same number of gates required for the desired application, with no room for re-functioning it once created.
Time to Market
If a project is time-critical and needs to offload products into the market quickly, then ASICs are the best choice. The reason is quite simple - they are already programmed and the users can directly place orders for the type of ASICs they require. On the contrary, FPGAs once bought require a logic code to run and the process of making and embedding the code on the chip takes time. Therefore, the time to market of ASICs is shorter when compared to FPGAs.
Barrier to Entry
The barrier to entry signifies the relative difficulty in acquiring technologies and using them. The barrier to entry in the case of ASICs is very high, considering the NRE costs, complex design flow, and other necessary investments required to get started. ASIC development involves investment in millions of dollars at a time to start, as they need foundry support and high-end software and development tools to start the development process.
On the contrary, the software and development tools required to develop FPGAs are readily available and cost-friendly when compared to ASICs.
The Bottom Line
Both FPGA and ASIC are suitable for different applications. It is critical to analyze the project nature and requirement and weigh all the points as mentioned earlier to come to a practical conclusion. FPGAs offer more flexibility, agility, scalability, and lower total investment costs where future modifications or changes are expected. In contrast, ASICs offer specific functionality, higher total investment cost and time to develop and get relayed into the market.
But there is a catch for those who have already acquired an ASIC in their product but now need to replace them due to End of Life (EOL) or modify them to suit changing requirements. System Level Solutions is one such service provider that holds the capability and knowledge resources to convert ASIC to FPGA. SLS offers a full spectrum of FPGA design, customization, and development services along with a full array of Intellectual Property Cores to help businesses pivot and expedite their manufacturing processes with an extra hand support.