Successful Design Of Power Management Chips

With an industry as large as semiconductors, there are often surprises lurking in some of the more specialized product categories. Everyone knows that huge chips such as CPUs and GPUs command high prices and that memory chips are ubiquitous. However, the domain of power management integrated circuits (PMICs) is less well known to many observers.

PMICs are impressive in terms of their technology. A single chip may include DC-to-DC conversion, battery charging, voltage scaling, power-source selection, power sequencing, and a range of miscellaneous functions. Many PMICs have multiple instances of these functions, such as several DC-to-DC converters, which are needed to be able to provide multiple voltages (5V, 3.3V, 1.8V, etc.), a requirement in most modern electronic devices.

Both complexity and market growth are driven by two key trends in the electronics industry:

• Proliferation of Internet of Things (IoT) and wearable devices
  • As the number of connected devices continues to grow, the demand for efficient and compact power management solutions increases. PMICs are essential for ensuring reliable power delivery and extending battery life in these devices.
• Technological advancements in consumer electronics
  • Consumer devices such as smartphones, tablets, and laptops require more powerful and energy-efficient components. PMICs are essential for managing power in these devices, ensuring optimal performance and longer battery life.

These industry trends lead to several concurrent trends in the development of increasingly sophisticated PMICs. One of these is the increasing level of integration and miniaturization. As electronic devices become more compact, there is a growing demand for smaller, more efficient power management solutions. Manufacturers are integrating multiple power management functions into a single chip, reducing the overall footprint and improving performance. This trend is particularly evident in smartphones, wearable devices, and IoT applications, where space is at a premium.

Advancements in semiconductor process technologies are also driving the development of more efficient and powerful PMICs. The transition from traditional silicon-based processes to advanced materials such as Gallium Nitride (GaN) and Silicon Carbide (SiC) is enabling greater efficiency and better thermal performance. These materials allow for higher switching frequencies, reducing the size of passive components and improving overall power density.

Energy harvesting is becoming increasingly important, especially in IoT and wearable applications. PMICs designed for harvesting can capture energy from ambient sources such as light, heat, and vibration and convert it into usable electrical power. This trend is driven by the need for sustainable and self-powered devices, reducing the reliance on batteries and extending the operational life of electronic systems.

Similarly, wireless power transfer (WPT) is gaining traction as a convenient and efficient method of charging electronic devices. PMICs are being developed to support various WPT technologies, including inductive, resonant, and capacitive coupling. This trend is driven by the proliferation of wireless charging solutions for smartphones, wearables, and other portable devices, offering users a seamless and cable-free charging experience.

Finally, artificial intelligence (AI) and machine learning (ML) are being integrated into PMICs to optimize power management. These technologies enable adaptive power management, where the PMIC can dynamically adjust power delivery based on real-time conditions and usage patterns. This results in improved energy efficiency and extended battery life. AI-driven PMICs are particularly relevant in complex systems such as data centers, automotive applications, and smart devices.

Designing PMICs that reflect all these trends and meet all the market requirements is an enormous challenge. Electronic design automation (EDA) vendors must innovate constantly, ensure smooth interaction between multiple tools, and work closely with foundries to develop an optimized design and verification flow with accurate process development kits (PDKs).

Accelerating PMIC design requires innovation in three main domains: efficiency, reliability, and time to market (TTM):

• Improving efficiency
  • Problem: inefficient design increases area, power, and temperature while reducing operating frequency and reliability
  • Solution: a high-performance, high-capacity simulation and design environment that can handle large designs while maintaining leading-edge performance
• Enhancing reliability
  • Problem: high voltage and current levels cause device breakdown, thermal, and timing issues
  • Solution: comprehensive device aging, thermal, and timing analysis that supports simulation of large, complex designs
• Shrinking TTM
  • Problem: larger, more complex designs increase design time and schedule, delaying product introduction
  • Solution: automatic highlighting of issues such as EM, IR-drop, and heating in a flow-driven environment

Addressing these issues makes the design process more efficient, reduces TAT and TTM, and improves reliability. Synopsys PrimeSim SPICE is a GPU-enabled SPICE simulator capable of handling large designs with complex parasitics while maintaining SPICE accuracy and is ideally suited for power management applications with long transient times, fast-moving voltages, and large currents.

A key care-about for PMIC designers is accurately characterizing and optimizing the resistance of the drain-source channel in power devices, known as Rdson. Synopsys Power Device Workbench is an advanced solution for extraction and analysis of metal interconnects in PMICs. It supports arbitrary complex, multiply connected interconnects. It identifies all resistive contributions to Rdson, including metal, wire-bonds, contacts, and vias, simulating current flow and voltage distributions.

Synopsys Power Device Workbench provides visualization of current density and voltage distributions, giving designers insight into the physics and operation of device interconnects. It optimizes metal, vias, and bond pad layouts, which are essential for an optimal design. Its rigorous and efficient field solver yields exact mathematical solutions, producing excellent agreement between simulation and measured results after actual wafers are processed.

Synopsys ETHAN (Electro-THermal ANalysis) is an electro-thermal simulator for PMICs. It combines R3D with a thermal engine using a detailed thermal mesh, based on the full (3D, static, and transient) geometry. Synopsys ETHAN is designed for ease of use. It integrates easily with simulation environments, including levering existing layout, technology, and rule files. Intuitive commands extend simulation to describe a simplified PMIC package by building a 3D structure layer by layer. A variety of text reports and graphical visualizations such as heat maps helps the designer understand the results.

The PrimeSim EMIR solution unifies production-proven and foundry-certified reliability analysis technologies covering electromigration and IR drop analysis. The integration with the PrimeWave Design Environment allows users to set up analysis options, run simulation and EMIR analysis, and view the violations for targeted evaluation and debugging. The environment allows users to overlay the results on the design layout and check net resistance for pads to pin and pads to internal instance pins.

As noted earlier, EDA vendors must work with foundries to develop and validate efficient and accurate PMIC development flows. Synopsys has worked closely with UMC, an industry leader in high-voltage process technologies. UMC provides state-of-the-art technologies such as Bipolar-CMOS-DMOS (BCD) that are ideally suited for PMIC implementation. Voltage ratings range from 5V to 200V to cover a wide variety of power-related applications. UMC provides its customers with user-friendly PDKs, design guidelines, sample layouts, and fundamental digital IP support. Synopsys has collaborated with UMC to develop PDKs for all UMC High-Voltage (HV) and BCD technology nodes.

Synopsys and UMC are also working closely with academia on this technology. As an example, the Indian Institute of Technology (IIT) in Kharagpur has designed several cutting edge PMIC projects using the Synopsys AMS flow and UMC technology. One such design of a DC-DC converter is shown below:

The IIT team also helped develop training labs for mutual customers using these PMIC designs built on UMC 180nm technology using Synopsys Custom and AMS tools in the silicon implementation flow.

The Synopsys Custom Design flow provides unique benefits for power electronics designers, and the close collaboration with UMC ensures that customers of this leading-edge foundry will have a seamless experience on their most challenging PMIC development projects.