Brendan Whelan (Analog Devices, California, USA)
Title: The Bandgap Reference: Achieving Stability in a Mass-Production World
Abstract: Precision measurement systems depend on the stability of the constituent components and circuit design over time and environmental conditions, which is often dominated by drift of a bandgap reference. This presentation will discuss theory of operation and root-cause of drift in bandgap references, with particular focus on the “soft” specs such as long-term drift, solder shift and thermal hysteresis. Foundational circuitry, various circuit architectures, and IC packaging will be reviewed, as well as system PCB design considerations. Difficulties in product manufacturing and test and current and future process trends will also be discussed.
Biography: Brendan Whelan is currently a Marketing and Applications Director at Analog Devices with a primary role as Precision Signal-Chain Architect. From 1999 to 2017, he was at Linear Technology, where he was an IC Designer and Design Manager, contributing to the design of several DC Precision products including LTC2054, LTC6102 and LTC6655. Before this he was at National Semiconductor, where he contributed to the design of mixed-signal blocks and automated testing for audio applications. He holds an MSc from Santa Clara University and a BSc from Rensselaer Polytechnic Institute.
Matthias Eberlein (Fraunhofer EMFT, Germany)
Title: Bandgap References: Recent Developments and Challenges in Nanometer CMOS
Abstract: This review surveys bandgap reference circuits from recent publications, highlighting advances in scaled CMOS and FinFET technologies. We examine solutions for achieving decent accuracy despite process variability, while emphasizing the limitations imposed by device models and temperature drift at sub‑1 V supplies. Moving beyond classic bipolar-based schemes, the talk examines unconventional ways of achieving all-CMOS integration in modern SoC’s. This includes techniques like weak-inversion, capacitive-bias and use of the bulk-diode. By discussing measured results and design tradeoffs, the presentation provides research directions for achieving robustness and high precision in advanced process nodes.
Biography: Matthias Eberlein received the German Diplom in Semiconductor Electronics from TU Darmstadt in 1995, and started his career with Infineon / Munich, working on cellular IPs. Later, he had assignments in Germany and Asia, including positions at Intel and Apple. After completing a PhD about bandgap references and thermal sensors at Johannes Kepler University in Linz/Austria, he is now with Fraunhofer EMFT in Munich. Matthias is an IEEE senior member, with several publications and about 30 patents. He is recipient of the first „IEEE Brokaw Award for Circuit Elegance“ in 2020. His main research interests include low-power, sensor and reference circuits in FinFET technologies.
Martin Lefebvre (Delft University of Technology, The Netherlands)
Title: A Family of Simple Current References Based on 2T Voltage References
Abstract: The robustness of current and voltage references to PVT variations is essential to the operation of ICs in real-world conditions. However, while voltage references can meet most of these requirements with a handful of transistors, current references remain rather complex. In this talk, we will present a family of simple current references consisting of a two-transistor (2T) voltage reference, buffered onto a voltage-to-current converter by a single transistor. We will demonstrate with experimental results from four fabricated references that they are suitable for pA to µA reference current generation, while also being PVT-robust and featuring low power and area overheads.
Biography: Dr. Martin Lefebvre received the MSc and PhD degrees from the Université Catholique de Louvain (Belgium) in 2017 and 2024, respectively. His PhD thesis, supervised by Prof. David Bol, focused on low-footprint PVT-robust current references for the IoT. He is now a postdoctoral researcher in the Cognitive Sensors Nodes and Systems Lab led by Dr. Charlotte Frenkel at TU Delft (The Netherlands). His current research interests include voltage and current references, hardware-aware bio-inspired machine learning algorithms, and low-power mixed-signal vision chips. He is a reviewer for several IEEE journals, including the JSSC and TCAS-I.
Pangi Park (KAIST, South Korea)
Title: A Sub-Ranging Current Reference with Process-Insensitive Second-Order TC Reduction
Abstract: Systems on Chip require stable current references to provide bias currents for analog blocks and define reference levels for current-domain ADCs. However, achieving a low temperature coefficient (TC) over a wide temperature range, while minimizing process-induced TC variation, is challenging due to the 2nd order TCs of most on-chip devices. This work presents a sub-ranging current reference that suppresses 2nd order TCs by combining a TC-adjustable current source and a process-insensitive sub-range detector. A prototype fabricated in 180-nm CMOS achieves a TC of 11.4 ppm/°C over −20 to 125 °C, measured on 45 samples across five corner wafers.
Biography: Dr. Pangi Park received the B.S. degree in Biomedical Engineering from Hanyang University, Seoul, South Korea, and the Ph.D. degree in Electrical Engineering from the Korea Advanced Institute of Science and Technology (KAIST), Daejeon, South Korea. He is currently a postdoctoral researcher at KAIST. His research interests include PVT/aging-robust precision analog and mixed-signal circuits, energy-efficient sensor interfaces, and AI-assisted circuit design for productivity and system-level integration.
Anne-Johan Annema (University of Twente, The Netherlands)
Title: Hybrid LC/RC Frequency References
Abstract: Frequency references are key building blocks of most electronic systems. To allow other subsystems, e.g. transmitters or ADCs to reach their target performance, they must maintain their accuracy over Process, Voltage, Temperature and lifetime (PVTL). In this talk, the design of a hybrid LC/RC frequency reference will be presented. The main focus of the talk will be on the design of its LC oscillator, since this sets the accuracy and aging behavior of the whole system. It will be shown that the sensitivity of an LC oscillator to finite Q is fundamentally dependent on the chosen topology. By choosing the appropriate topology, and combining it with a low-power RC-based oscillator and a non-conventional temperature compensation scheme, the resulting hybrid frequency reference achieves state-of-the-art accuracy (~0.7ppm/K) over PVTL.
Biography: Anne-Johan Annema received the MSc and PhD degrees in electrical engineering from the University of Twente, Enschede, The Netherlands, in 1990 and 1994, respectively. After that, he joined Philips Research in Eindhoven, The Netherlands, where he worked on a number of physics-electronics-related projects at the “Semiconductor Device Architecture” and the “Mixed-Signal Circuits and Systems” departments. In 2000, he joined the IC-Design group of the University of Twente. His research interests cover many aspects of analog and mixed-signal electronics, usually involving a fair bit of physics and math. He is also a part-time consultant to industry and a co-founder of ChipDesignWorks.
Karimeldeen Mohamed (Delft University of Technology, The Netherlands)
Title: A High-Stability High-Accuracy RC Frequency Reference
Abstract: Modern electronic systems require stable frequency references for timing, synchronization, and communication. While crystal, BAW, and MEMS oscillators offer excellent stability, their co-integration with CMOS is difficult. RC-based references are fully CMOS-compatible, but their stability is limited by resistor temperature dependence and aging. This talk presents a high-stability 16MHz RC frequency reference implemented in a standard 180nm CMOS process. It consists of a frequency-locked loop, whose output frequency is locked to the time constant of a Wien bridge filter made from silicided resistors and MIM capacitors. A temperature compensation scheme based on a PNP-based temperature sensor results in ±350ppm inaccuracy from −45°C to 85°C after a 2-point trim, which increases to only ±450ppm after accelerated aging.
Biography: Karimeldeen Mohamed received his B.Sc degree from Suez Canal University in 2017, as the top ranked student in the Faculty of Engineering. After fulfilling his compulsory military service in 2019, he joined Suez Canal University as a full-time TA. In 2020, he joined Master Micro as an analog automation design engineer. In parallel, he obtained an MSc from Ain Shams University on the design automation of LDOs. He is currently pursuing his Ph.D. degree with the Electronic Instrumentation Lab at Delft University of Technology, the Netherlands.