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Power efficiency is the name of the game for today’s chip designs, especially applications in electric vehicles (EV), renewable energy, cloud computing, and mobile. It’s not hard to see why reducing energy losses can result in huge benefits. In EVs, for instance, we can experience less time to charge, faster acceleration, longer range, and more. At the root of these benefits is an efficient power device.
Power semiconductor devices are the workhorses of power management systems. They are typically used as switching devices and rectifiers, with the ability to change the voltage or frequency of an electrical current. As they are designed to operate in the ON state, the goal is to optimize usage in this mode.
Beyond efficiency, power devices provide regulated power to systems or integrated circuits (ICs), ensuring more reliable operation. The drive for greater efficiency and reliability has created a need for larger devices, increasing the cost and time to market. This is one of the reasons why power device designers are moving to silicon carbide (SiC) and gallium nitride (GaN); these materials’ lower resistivity allows for higher efficiencies in smaller packaging.
Read on to learn more about the challenges in power semiconductor device design, how Synopsys Power Device Workbench helps address these issues, and its key features that improve efficiency.
The Biggest Challenges of Designing Power Semiconductor Devices
It may come as no surprise that efficiency stands out as both the most important metric and the biggest challenge for power devices. The driving force of efficiency is primarily measured by the ON resistance of the device. In addition to efficiency, several other challenges demand attention, including:
• Current density: Ensures the design meets electromigration (EM) rules
• Device turn on/turn off delay: Ensures the complete device turns on within a defined time window
• Switching losses
Even though design size is increasing, the main goal is to drive the maximum amount of current through the smallest area possible. This has the potential to cause EM failures, making the design unreliable. Identifying these issues and fixing them with little other impact is one of the major challenges in power device design.
As such, navigating the complexity and size of large designs (especially SiC designs) has become a significant factor. Designers must navigate the heightened switching frequencies characteristic of these designs along with their substantial size. The sheer dimensions of these designs mean that the gate signal (the trigger for device activation) may take longer to propagate across the entire structure. This delay results in parts of the device activating before others, causing uneven current distribution, higher current density, and potential reliability issues.
As we delve into larger and more efficient designs, switching losses have become a significant contributor to loss of efficiency. Integrated device manufacturers can alter and enhance transistors, giving them more flexibility than fabless companies who are often stuck using the transistors supplied by their foundry. Because this is a transient problem, a detailed analysis to understand the impacts of switching is required. Understanding the holistic impact of a change, especially with the complex routing inherent in large devices, is essential. The ability to visualize and compare the impact across multiple similar layouts becomes a vital asset in overcoming these challenges.
Tackling these challenges demands a comprehensive approach. Enter Synopsys Power Device Workbench, a robust solution that ensures maximum efficiency and reliability in the ever-evolving world of power semiconductors.
Why Power Device Workbench?
Power Device Workbench (PDW) is the leading tool in the power device market. PDW has been used to optimize designs across all technology nodes down to 4nm and is especially helpful in large designs. Designers apply PDW once the initial layout of the design is available, seamlessly accompanying the development journey until the design is signed off as completed.
When designers are shopping around for a tool to optimize power transistors and electronic devices, the most important factors include the ability to improve efficiency, quickly compare different designs and enhancements, review different routing schemes, optimize the redistribution layer (RDL), and quickly correct electromigration (EM) violations.
At the core of PDW’s prowess is its ability to meticulously and quickly analyze and simulate the intricate details of power devices. The tool focuses on resistance and current flow within complex metal interconnects. By employing a high-throughput simulation engine, PDW empowers engineers to optimize critical design parameters like metal layouts and bond wire configurations as well as analyze the full gate network (which is extremely difficult in large, complex designs). The result? Better-designed products that can hit the market faster.
Power Device Workbench Key Features
Power Device Workbench offers a suite of key features that elevate its capabilities and set it apart from other tools in the field.
- Analyzing Designs of All Sizes: PDW excels in handling designs of all sizes, surpassing the limitations of many other tools. Its capability extends to addressing all types of routing complexities, providing designers with a comprehensive understanding of the ON resistance. This insight becomes the foundation for targeted improvements, ultimately enhancing the overall efficiency of the power device.
- Full Gate Network Handling: For large circuits, PDW takes center stage by seamlessly handling the full gate network. This is crucial for ensuring that the entire device turns on within a very short window, a critical factor in meeting reliability goals. By identifying specific areas in the network that require enhancement, PDW aids designers in optimizing the reliability of large circuits.
- Package Handling: PDW goes beyond the chip itself by including the design’s package. In high-efficiency designs, the package plays a pivotal role. PDW navigates the redistribution layer within the package, connecting it to chip locations with wider metal and contributing to efficiency improvements. In addition, PDW assists in optimal sensor placement within the design, ensuring the correct operation of power devices through strategic positioning of thermal and current sensors.
- Automatic Correction of Electromigration Violations: When the current density within the design exceeds acceptable limits, PDW precisely pinpoints the occurrence and specifies the layer of metal and the actual value of current density. It then automatically reroutes the design, eliminating EM issues and ensuring compliance with design standards.
- Comprehensive Design Optimization: Whether it’s improving ON resistance, optimizing the gate network for timely activation, enhancing the RDL in packaging, or exploring the design area to achieve specific resistance targets, PDW provides a multifaceted approach to optimizing power devices.
- Automatic Comparison of Design Differences: A standout feature of PDW is its ability to automatically compare design differences. When designers make changes, PDW swiftly assesses the impact on overall performance across every layer. This capability is invaluable for understanding the global implications of local modifications, empowering designers to make informed decisions that positively influence the entire design.
- Integration with PrimeSIM: As switching losses are a transient effect, PDW creates a distributed device model that is used by PrimeSIM. PDW can display the current and voltage map of the design at any time during the transient simulation.
Ultimately, PDW accelerates the optimization process, delivering high-quality results in a very short timeframe. PDW emerges not just as a tool but as a catalyst for innovation, providing engineers with the means to push the boundaries of power device efficiency and reliability. As technology continues to evolve, PDW remains at the forefront, ensuring that power devices are not just designed but optimized for maximum efficiency and reliability.
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