Embedded FPGA Developments in 130nm and 28nm CMOS for Reconfigurable Machine Learning in Particle Detector Readout

Core Concepts

Embedded FPGA technology enables the implementation of reconfigurable logic within application-specific integrated circuits (ASICs), offering the low power and efficiency of an ASIC along with the ease of FPGA configuration, which is beneficial for machine learning applications in the data pipeline of next-generation collider experiments.

Abstract

This work describes the design and fabrication of embedded FPGAs (eFPGAs) using the 130nm and 28nm CMOS technology nodes, leveraging the open-source "FABulous" framework. The eFPGA technology offers a unique combination of flexibility, low power, and small footprint, making it an ideal tool for data acquisition challenges in collider physics.
The 130nm eFPGA design was successfully tested, demonstrating the basic functionality of the eFPGA through a simple counter test and power measurements. To address the need for increased logic density, enhanced radiation hardness, and reduced power consumption, the design was later transitioned to the 28nm CMOS technology node.
The 28nm eFPGA design was also successfully tested, including a simple counter test, power measurements, and an AXI stream loopback test in the eFPGA. As a proof-of-concept, the 28nm eFPGA was used to implement a Boosted Decision Tree (BDT) model for machine learning-based pileup classification in a simulated particle detector readout scenario. The BDT model was successfully synthesized and configured onto the eFPGA, achieving 100% accuracy compared to the golden software results.
Further development of the eFPGA technology and its application to collider detector readout is discussed, including the need for larger logical capacity, improved radiation tolerance, and co-design of high-performance sensor processing algorithms.

Stats

The 130nm ASIC's core voltage rail power consumption at a 125 MHz clock is approximately 1.5 W.
The 28nm ASIC's core voltage rail power consumption at a 125 MHz clock is approximately 0.5 W.

Quotes

"eFPGA technology allows the implementation of reconfigurable logic within the design of an application-specific integrated circuit (ASIC). This approach offers the low power and efficiency of an ASIC along with the ease of FPGA configuration, particularly beneficial for the use case of machine learning in the data pipeline of next-generation collider experiments."
"The unique features of the eFPGA, namely its high degree of flexibility, relatively low power and footprint, and publicly accessible design framework make it an ideal tool for known data acquisition challenges in collider physics."

Key Insights Distilled From

Embedded FPGA Developments in 130nm and 28nm CMOS for Machine Learning in Particle Detector Readout

by Julia Gonski... at arxiv.org 04-30-2024

https://arxiv.org/pdf/2404.17701.pdf

Deeper Inquiries

How can the eFPGA design be further optimized to achieve higher logic density and improved radiation tolerance for deployment in future collider detectors?

To enhance the eFPGA design for increased logic density and better radiation tolerance in future collider detectors, several optimization strategies can be implemented. Firstly, the utilization of advanced semiconductor technologies, such as FinFET or FD-SOI, can enable higher logic density due to their superior scalability and reduced leakage currents. These technologies offer improved radiation hardness, crucial for the high radiation environments in collider detectors.
Moreover, the eFPGA architecture can be optimized by implementing redundancy techniques like Triple Modular Redundancy (TMR) to enhance radiation tolerance. TMR involves triplicating logic circuits and comparing the results to mitigate single-event upsets caused by radiation. This redundancy adds a layer of fault tolerance, ensuring reliable operation in harsh radiation conditions.
Furthermore, the eFPGA layout can be optimized for radiation tolerance by incorporating shielding techniques and layout modifications to minimize the impact of ionizing radiation on the device. Shielding materials like heavy metals can be integrated into the packaging to absorb radiation and protect the sensitive components of the eFPGA.
Additionally, the design can incorporate error correction codes (ECC) to detect and correct radiation-induced errors in the configuration memory of the eFPGA. ECC adds redundancy to the memory storage, enabling the detection and correction of bit errors caused by radiation.
By combining these strategies, the eFPGA design can achieve higher logic density and improved radiation tolerance, making it well-suited for deployment in future collider detectors where reliability and performance in high-radiation environments are paramount.

What are the potential challenges and trade-offs in integrating more complex machine learning models onto the eFPGA while maintaining low power and small footprint?

Integrating complex machine learning models onto the eFPGA while balancing low power consumption and a small footprint presents several challenges and trade-offs. One significant challenge is the limited resources available in the eFPGA, such as LUTs, registers, and DSP slices, which may restrict the size and complexity of the machine learning models that can be implemented. This limitation can lead to trade-offs in model accuracy and performance.
Another challenge is the need for efficient utilization of resources to minimize power consumption while running complex machine learning algorithms. Optimizing the design for power efficiency may require sacrificing some level of model complexity or accuracy to stay within the power constraints of the eFPGA.
Furthermore, the reconfigurability of the eFPGA introduces challenges in efficiently mapping and optimizing machine learning algorithms for hardware implementation. The conversion of software-based models to hardware-friendly designs may involve trade-offs in terms of computational efficiency and resource utilization.
Moreover, the trade-off between model complexity and inference speed is crucial when integrating complex machine learning models onto the eFPGA. Increasing the complexity of the model may enhance accuracy but could also lead to longer inference times, impacting real-time processing capabilities.
Balancing these challenges and trade-offs requires careful optimization of the machine learning algorithms, resource allocation, and power management strategies to ensure optimal performance within the constraints of the eFPGA's low power and small footprint requirements.

What other scientific or industrial applications could benefit from the reconfigurable and low-power capabilities of the eFPGA technology beyond particle physics?

The reconfigurable and low-power capabilities of eFPGA technology offer significant benefits beyond particle physics, extending to various scientific and industrial applications. One such application is in autonomous vehicles, where eFPGAs can be utilized for real-time sensor data processing, enabling efficient decision-making and control algorithms with low latency and power consumption.
In the field of telecommunications, eFPGAs can enhance network infrastructure by enabling flexible and adaptive signal processing for tasks like beamforming in 5G networks. The reconfigurability of eFPGAs allows for dynamic adjustments to changing network conditions, optimizing performance and efficiency.
In the healthcare industry, eFPGAs can be employed for medical imaging applications, such as MRI and CT scanners, to accelerate image processing tasks and improve diagnostic accuracy. The low-power characteristics of eFPGAs make them suitable for portable medical devices and wearable health monitoring systems.
Furthermore, in aerospace and defense, eFPGAs can enhance radar and signal processing systems, enabling rapid adaptation to evolving threats and scenarios. The reconfigurable nature of eFPGAs allows for on-the-fly adjustments to mission-critical algorithms while maintaining low power consumption.
Overall, the versatility of eFPGA technology makes it applicable to a wide range of scientific and industrial domains, offering reconfigurable and low-power solutions for data processing, signal analysis, and control applications beyond the realm of particle physics.