Area-Efficient nA-to-µA Constant-with-Temperature CMOS Current References for the Internet of Things
(2024)
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- Authors
- Supervisors
- Bol, David
- Abstract
- For more than a decade, Internet-of-Things (IoT) applications have driven the development of edge sensor nodes, which must operate on a limited power budget, occupy a small silicon area, and be robust to process, voltage and temperature (PVT) variations. In such a sensor node, current references are crucial components as their sensitivity to PVT variations impacts the performance of analog circuits and thereby, of the node itself. In this thesis, we first identify the key principles employed to generate a constant-with-temperature (CWT) current and analyze which of them are well suited to the requirements of the IoT. Then, we develop several current references with a focus on generating a nA-range CWT current and on reducing area. These references use a resistor or self-cascode MOSFET as voltage-to-current converter, whose bias voltage is either generated by a two-transistor voltage reference, or by forward body biasing, to obtain a small threshold voltage difference between two identical transistors. These concepts are demonstrated through post-layout simulations and measurements of four chips in various technologies, and significantly improve existing references in terms of temperature coefficient and area. At last, an in-depth analysis of the literature reveals that applications requiring a CWT current are less numerous than usually claimed, and that CWT current references should thus be regarded as a stepping stone towards other applications rather than a goal in itself.
- Affiliations
Citations
Lefebvre, M. (2024). Area-Efficient nA-to-µA Constant-with-Temperature CMOS Current References for the Internet of Things. https://hdl.handle.net/2078.5/233820