Designing Custom ASICs vs. Using Off-the-Shelf Components: Pros and Cons

In embedded systems design, the choice between developing a custom Application-Specific Integrated Circuit (ASIC) and using off-the-shelf components is pivotal. Each approach brings unique advantages and drawbacks, impacting everything from performance and power consumption to cost and time-to-market. As the demand for customized, high-performance embedded systems grows, engineers face tough decisions regarding the best path forward. This article will delve into the pros and cons of designing custom ASICs versus using off-the-shelf components to help embedded engineers make informed choices tailored to their project needs.

Understanding Custom ASICs and Off-the-Shelf Components

Custom ASICs

Custom ASICs are highly specialized chips designed to meet the specific needs of a particular application. Unlike general-purpose integrated circuits, ASICs are purpose-built, which allows for optimization in areas such as power efficiency, size, and performance. Designing an ASIC requires a deep understanding of the intended application, a significant upfront investment, and a long development cycle. However, the results can be remarkably rewarding, especially for high-volume products where the per-unit cost is amortized over time.

Off-the-Shelf Components

Off-the-shelf components, on the other hand, refer to commercially available chips like microcontrollers (MCUs), field-programmable gate arrays (FPGAs), and other integrated circuits (ICs) that are designed for a wide range of applications. These components are readily available, require no specialized manufacturing, and can be used almost immediately. They are ideal for lower-volume production runs or projects with tight timelines, where the benefits of customization are outweighed by the ease and affordability of using pre-existing solutions.

Advantages of Custom ASICs

1. Enhanced Performance: Custom ASICs are optimized for specific tasks, allowing for higher performance levels than general-purpose components. This is especially valuable in high-frequency or data-intensive applications, such as those found in telecommunications and automotive embedded systems.
2. Lower Power Consumption: One of the significant advantages of ASICs is their potential for optimized power efficiency. Custom ASICs can achieve lower power consumption by eliminating unnecessary components and functions, a critical feature for battery-powered and IoT devices.
3. Compact Size and Lower Weight: ASICs can be tailored to occupy minimal board space, which can result in smaller, lighter designs. This is crucial for applications where form factor and weight are primary concerns, such as wearables, mobile devices, and aerospace applications.
4. Greater Security: Custom ASICs offer improved security because they can be designed to incorporate security features like encryption engines and secure boot processes. Additionally, they are more challenging to reverse-engineer, providing a safeguard against IP theft.
5. Long-Term Cost Efficiency: Although ASICs have high initial costs, they can provide significant cost savings in high-volume production. By eliminating licensing fees and recurring costs associated with off-the-shelf components, custom ASICs can reduce per-unit costs over time, making them economically viable for large-scale applications.

Drawbacks of Custom ASICs

1. High Development Costs: Developing a custom ASIC involves substantial non-recurring engineering (NRE) costs, including design, validation, testing, and fabrication. For low-volume projects, this cost can be prohibitively high.
2. Extended Time-to-Market: The ASIC development cycle is considerably longer than using off-the-shelf components. From design to manufacturing, it can take 12-24 months, a timeline that may not align with fast-paced markets or projects with urgent deadlines.
3. Limited Flexibility: Once an ASIC is fabricated, its functionality is fixed. Unlike FPGAs, ASICs cannot be reprogrammed, which limits their adaptability in rapidly changing environments or applications that require frequent updates.
4. Risk of Obsolescence: ASICs are designed for specific tasks, and if those tasks become obsolete or requirements change, the ASIC may no longer be relevant. This risk can lead to costly redesigns or even the need for a completely new ASIC.
5. Dependency on Foundries: Manufacturing custom ASICs requires access to specialized semiconductor foundries, which may involve extended lead times and production delays due to high demand or geopolitical issues affecting semiconductor production.

Advantages of Off-the-Shelf Components

1. Lower Initial Costs: Off-the-shelf components are mass-produced, making them much more affordable than custom ASICs, particularly for low- and medium-volume applications. They allow companies to avoid the high NRE costs associated with ASIC development.
2. Faster Time-to-Market: Off-the-shelf components can be sourced, integrated, and deployed in significantly less time than custom ASICs. This rapid deployment is crucial for industries where speed and market agility are essential, such as consumer electronics and medical devices.
3. Flexibility and Programmability: Many off-the-shelf components, especially FPGAs and MCUs, are programmable and can be reconfigured post-deployment. This flexibility is ideal for prototyping, testing, and applications that may require regular updates or feature expansions.
4. Wider Support and Documentation: Off-the-shelf components often come with extensive documentation, reference designs, and technical support from the manufacturer. These resources can be invaluable, especially for smaller engineering teams that may not have specialized ASIC expertise.
5. Reduced Risk of Obsolescence: Because off-the-shelf components are widely used and supported, they are often produced for longer lifespans. Manufacturers typically provide clear product lifecycle information, allowing engineers to plan around component availability and support.

Drawbacks of Off-the-Shelf Components

1. Suboptimal Performance for Specialized Tasks: While versatile, off-the-shelf components are generally designed to meet a broad range of applications. They may not perform as well as a custom ASIC in applications requiring highly specialized processing or ultra-low power.
2. Higher Power Consumption: Off-the-shelf components often consume more power than custom ASICs, as they include features and capabilities that may not be necessary for a specific application. This excess power usage can be a disadvantage in battery-powered and energy-sensitive applications.
3. Increased Board Space Requirements: Off-the-shelf solutions may require more space on the PCB due to their general-purpose design. This can pose challenges in space-constrained designs, where a more compact ASIC would be ideal.
4. Limited Customization and Optimization: Engineers using off-the-shelf components have limited control over internal architecture, potentially leading to compromises in design. This is particularly challenging for high-performance applications, such as high-speed data processing and real-time control systems.
5. Potential Licensing and Royalty Fees: Some off-the-shelf components require licensing fees, especially if they incorporate patented technologies. These recurring costs can add up over time, particularly in high-volume applications.

Key Considerations for Choosing Between Custom ASICs and Off-the-Shelf Components

When deciding between custom ASICs and off-the-shelf components, embedded engineers should consider the following factors:

1. Project Volume: High-volume projects are better suited for custom ASICs due to their long-term cost efficiency, while low- to medium-volume projects benefit from the affordability of off-the-shelf components.
2. Time-to-Market: If a project has a strict timeline, off-the-shelf components are typically the best choice due to their immediate availability. ASIC development can take a year or more, which may be too slow for competitive markets.
3. Design Complexity and Performance Needs: For applications that require optimized performance, minimal power consumption, or advanced security, a custom ASIC may be worth the investment. In less demanding applications, off-the-shelf components can often deliver adequate performance at a fraction of the cost.
4. Flexibility Requirements: Projects that may undergo changes or require regular updates are better suited for programmable off-the-shelf components like FPGAs. ASICs are inflexible once fabricated, making them more appropriate for stable applications.
5. Budget Constraints: Custom ASICs are costly to develop and require a substantial budget for design, testing, and fabrication. Off-the-shelf components are ideal for projects with limited financial resources, as they eliminate the need for high upfront investment.

Case Studies: Choosing the Right Solution

Case Study 1: Consumer Electronics Device

For a wearable fitness tracker, a company opted for a custom ASIC to achieve a slim form factor and maximize battery life. The ASIC was optimized for ultra-low power and included only the essential functions for health monitoring, significantly reducing power consumption compared to off-the-shelf MCUs. While the development process took longer, the product’s low power usage and compact size gave it a competitive advantage in the market.

Case Study 2: Industrial Automation System

An industrial automation company needed a flexible solution for a prototype machine-learning application in factory settings. They chose an off-the-shelf FPGA, which allowed them to experiment with different configurations and update the model as new data became available. The FPGA’s programmability was critical, as it enabled the team to adapt the design in real-time without needing to redesign a custom chip.

Case Study 3: High-Performance Computing

A telecommunications company working on 5G technology needed high processing speed and efficiency. The project’s high volume and specialized processing needs justified the high NRE cost of an ASIC. By designing a custom ASIC tailored for high-speed data processing, the company achieved the required performance while minimizing power usage, making it a cost-effective choice in the long term.

The Future of ASICs and Off-the-Shelf Components in Embedded Engineering

As technology advances, the gap between ASICs and off-the-shelf components is narrowing in some areas. For example, high-end FPGAs are increasingly capable of performing complex tasks once reserved for ASICs, and advanced MCUs now offer specialized functionality for specific applications. Additionally, companies are beginning to explore hybrid approaches, such as system-on-chip (SoC) solutions, which combine the flexibility of programmable elements with the performance benefits of custom circuitry.

For embedded engineers, these developments offer exciting opportunities to mix and match solutions. Engineers can choose an off-the-shelf component for the initial prototyping phase and transition to a custom ASIC for mass production, leveraging the strengths of each approach to 

Conclusion

Choosing between custom ASICs and off-the-shelf components is a nuanced decision that depends on a project’s requirements, budget, and timeline. Custom ASICs offer performance, efficiency, and security advantages but come with high costs and lengthy development times. Off-the-shelf components are faster to market, more affordable, and flexible but may lack the optimizations needed for specialized applications.

For embedded engineers, understanding the trade-offs and carefully assessing project needs is crucial. By considering the advantages and drawbacks of each approach, engineers can make informed decisions that align with their project goals, ultimately leading to innovative, high-quality embedded systems. Whether you’re developing IoT devices, automotive control systems, or industrial automation solutions, balancing customization with practicality will be key to successful embedded engineering in an ever-evolving industry.