Adaptive Voltage Scaling (AVS): Enhancing Chip Performance and Efficiency

Adaptive Voltage Scaling (AVS) is a critical technique in the semiconductor industry to optimize the performance and power efficiency of Integrated Circuits (ICs). In this whitepaper, we will delve into the principles and implementation of AVS, exploring how it addresses the challenges posed by process variation and how it contributes to delivering a seamless user experience. Additionally, we will position AVS with other solutions like Dynamic Voltage Frequency Scaling (DVFS) to get a global picture.

Understanding Process Variation and Corner Tightening

In semiconductor manufacturing, technology deviation is an inevitable reality: all foundries (GF, TSMC, SMIC and others) face variations in their manufacturing processes, leading to performance discrepancies among individual devices. Silicon vendors provide models that describe the extreme variations of the process parameters, allowing IC designers to compensate by design the subsequent impacts on their chip performances. Those extreme variations are called process corners.

Corners understanding

Most ICs are mainly based on two types of field-effect transistors (FETs): PMOS (P-type Metal-Oxide-Semiconductor) and NMOS (N-type Metal-Oxide-Semiconductor) transistors. A PMOS device conducts when his gate voltage is LOW while a NMOS device conducts when his gate voltage is HIGH. The performances of PMOS and NMOS transistors are either classified as typical (T), slow (S) or fast (F). The industry uses 2-letter designations: 1st letter refers to the NMOS; 2nd letter refers to the PMOS. Therefore, a matrix can be shaped from all the possible process combinations, highlighting the said “process corners” (see fig.1).

Dynamic Voltage and Frequency Scaling (DVFS)

Dynamic Voltage Frequency Scaling (DVFS) is a power management technique that adjusts voltage and frequency based on workload demands. It lowers voltage and frequency for light tasks, reducing power consumption, and increases them for high-demand tasks, boosting performances.

Introducing Adaptive Voltage Scaling (AVS)

AVS presents a smarter and more efficient approach to managing process variation. AVS does not just rely on a set of predefined operating conditions; it dynamically adjusts the supply voltage of the device based on real-time conditions through a close loop that senses the impacts of the operating environment and provides the necessary corrections.

AVS Mechanism

The AVS mechanism directly monitors the impacts of all the operating factors on the circuit performances - including temperature, workload, voltage droop and threshold voltage variations. By continuously assessing the impact of these parameters, AVS can determine the minimum supply voltage required to maintain consistent performance, thus optimizing the power consumption.

Benefits of AVS

Improved efficiency: AVS allows the device to operate at the most suitable voltage for a given task, ensuring optimal performance without over-provisioning power. Being adaptive, AVS responds to real-time conditions, providing more accurate and efficient voltage scaling.

Enhanced Power Efficiency

By dynamically scaling down the supply voltage, AVS minimizes power consumption, resulting in extended battery life for mobile devices and reduced power costs for data center.

?Device Aging

AVS ensures that the chip operates at the lowest possible voltage, reducing the risk of premature aging and increasing the overall lifespan of the device.

?Conclusion

Adaptive Voltage Scaling (AVS) is an advanced technology that revolutionizes the way semiconductor devices handle process variation and power management. By intelligently adjusting supply voltage based on real-time conditions, AVS optimizes performance, power efficiency and overall user experience. As semiconductor technology continues to advance, AVS will play an increasingly vital role in shaping the future of electronics.