Short Course 3 (Circuits)

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Advanced Circuits and Systems for Internet-of-Things (IoT) Sensors

Moderators: Po-Hung Cheng (NCTU) and Danielle Griffith (TI)

This short course covers key design aspects of IoT sensors, including wide spectrum of CMOS/non-CMOS sensor design, power management for energy harvesting, low-power analog/RF/digital circuits, physical attack protections for security. Two complete IoT sensor systems will also be showcased by a computer vision sensor system and a battery-free BLE sensor system.

Live Q&A Session: June 14, 7:00AM-8:30AM (JST)

CMOS Sensor for IoT: First Frontier, Stefano Pietri, NXP Semiconductors

The concept of IoT was coined in 1999 but I only became aware of its meaning around 2010 as our CEO mentioned it at an all-hands meeting. It seems a long time and yet today, about ten years later, many applications like home automation, wearables, healthcare, manufacturing, agriculture, smart city, and transportation are barely at the beginning. IoT exists today also thanks to the steady and incremental advances in CMOS sensors technologies: after all, we are still measuring voltages, charge, and currents. In this short tutorial, we will explore the state of the art of CMOS sensors including temperature sensors, touch sensors, heart rate sensors, voice sensors, and other CMOS sensors at the heart of IoT applications today, which I nerdly refer to as the “first frontier”. We will also quickly glance at sensor research which I believe will lead us into a new generation of IoT sensors aimed at improving our quality of life by repairing and augmenting the human body.

Non-CMOS Based Sesors for IoT, Marcel Zevenbergen, imec

The deployment of IoT technologies, using a wireless network of compact, cost-effective and low-power sensors, makes it possible to collect finer grained information on processes in for instance, gas, liquid and bioprocessing monitoring, on a large scale and in real time. By analyzing this data and combining it with other information sources, it becomes possible to create easily accessible analytical models for a wide range of applications. However, developing miniaturized transducers often requires using non-CMOS processes or materials, or it requires a hybrid approach in which additional non-CMOS sensing layers are processed on CMOS-based devices. In this presentation, I will provide an overview of the progress in miniaturized IoT sensors in various applications, the market requirements and the (material) challenges facing the device development.

Capacitive Power Management Circuits for Miniaturized Energy Harvesting IoT Systems, Man-Kay Law, University of Macau

The continuous growth of IoT has enabled billions of sensor-enabled devices with diverse connectivity and energy harvesting capability. With the next generation IoT targeting on smart solutions with embedded intelligence at the edge, efficient energy conversion within an ultra-compact volume is necessary to meet the ever increasing energy needs. This presentation will first introduce the energy requirements of IoT devices, followed by energy harvesting basics. We will then discuss power delivery topologies and elaborate on the recent advances in capacitive power management circuits for miniaturized IoT systems.

Getting the Most Out of a Little: Ultra-Low Power Circuit Techniques for the IoT, Drew A. Hall, University of California, San Diego

Advances in semiconductor technology over the last several decades have caused an influx of electronic devices into our daily lives, leading to the emergence of the IoT era. The IoT is a cluster of many miniaturized devices (also called sensor nodes) that unobtrusively capture data from our lives and the surrounding environment. The IoT will have a transformative impact on a wide variety of applications ranging from biological sensing such as wearable sensors to track our well-being, to physical sensors for industrial and environmental monitoring, to entertainment and infrastructure-related devices for smart-homes and smart-cities. From a circuit design perspective, enabling the IoT requires overcoming a significant technological hurdle: maximizing energy efficiency. This has steered the focus of research towards sub-µW operation to extend the battery life or support wireless/harvested power for long-term continuous monitoring. Unfortunately, ultra-low-power consumption often comes at the expense of temperature robustness. Techniques to reduce power consumption while maintaining robustness to temperature variation will be covered in this talk. Emphasis is placed on analog front-ends, oscillators, and RF transmitters with examples of each.

Low Power and Energy-Efficient Digital CMOS for Mixed-Signal Sensor Interfaces, Segio Bampi, Federal University of Rio Grande do Sul

Autonomic devices require ultra-low energy operation over their lifetime. Digital and mixed-signal circuit design techniques for IoT interfaces at the analog-to-digital domain transition are reviewed. How to design digital circuits (like MCUs) for a wide dynamic range of voltage-frequency power modes will be stressed. The nano-power range which is achievable in deca-nanometer CMOS requires applying very specific logic design techniques such as performance-efficiency modes and near-threshold (NVT) operation for low-frequency and maximum energy efficiency. The strategy for sizing transistors in digital cells and maximizing static noise margin in NVT modes will be explained. Recent mixed-signal approaches, with mostly digital operators to implement UL-energy operational transconductance amplifiers, comparators, voltage references, and A/D converters with dyadic pulse modulation schemes will be focused in this talk. These circuits allow processing of low-frequency analog signals, typical of sensor interfaces, at unprecedented levels of energy efficiency.

IC-Chip Level Physical Attack Protections for IoT Security, Makoto Nagata, Kobe University

IC chips are key enablers of a densely networked smart society by securing digital data with cryptography and authentication functionality. However, security devices are threatened by adversarial attempts in practical utilization environment. This talk will focus on the protection schemes of IC chips in the vertical unification of systems, circuits, and packaging technologies. Topics include attack models on crypto systems and associated design principles of on-chip monitoring circuits to sense and detect malicious attempts. Further, the backside buried metallization is exploited to achieve secure IC chip structures. Silicon experiments will be detailed for passive and active attacks, respectively through electromagnetic emissions and laser fault injections.

Image Sensor Technologies for Computer Vision Systems to Realize Smart Sensing, Atsushi Nose, Sony Semiconductor Solutions Corporation

CMOS image sensors are widely used not only in video cameras, digital still cameras, and smartphones, but also in security-monitoring, in-vehicle, and medical applications. Their productivity and performance have been improving through the development of basic semiconductor technology and stacked structural technology. In particular, the stacked CMOS image sensor has made possible the inclusion of various processing functions on sensor edge and has been expanding its applications. In this presentation, we explain the evolution of CMOS image sensors, Vision Sensor with AI processing, and the features of intelligent vision sensors that realize smart sensing.

Design Considerations for Battery-Free and Crystal-Less Bluetooth-LE Sensors for Low-Cost Labels, Alon Yehezkely, Wiliot

Adding wireless sensing capabilities to products can scale the IoT market towards a trillion units. However, this requires the enablement of extremely low-cost wireless sensors and an infrastructure which is available and affordable. RFID technology has enabled the manufacturing of billions of labels with integrated circuits at a price that goes below 5 cents, but it lacks the infrastructure commoditization and availability of WiFi or Bluetooth-LE (BLE). As BLE technology is presently not targeting the implications of extreme cost reduction, we will discuss the system-level considerations of the development of ultra-low-cost BLE sensor tags: selection of the wireless technology, radio architecture, crystal-less operation, RF-based energy harvesting, power management, and sensors.