An Analysis of a Symmetric Circuit Topology for Ultra-Low Power Voltage Scaling in Deep Nanoscale CMOS

Weinberg, Elena, Computer Engineering - School of Engineering and Applied Science, University of Virginia
Stan, Mircea, Department of Electrical and Computer Engineering, University of Virginia

As integrated circuits (ICs) continue to scale, power consumption has become an important concern, making sub-threshold (sub-VT) operation an attractive route for ultra-low power (ULP) applications, especially those that harvest energy from the environment. However, a major roadblock lies in increased sensitivity to process variations both at near- and sub-VT. Additionally, temperature variations can be detrimental to circuit functionality for energy harvesting applications operating in outdoor environments. This vulnerability to variations at the device level is exacerbated by imbalances between pull-up (PUN) and pull-down (PDN) networks at the circuit level. This thesis presents a symmetric circuit topology in conjunction with a biasing scheme that maintains symmetrically robust operation of ULP energy harvesting systems in a variety of climates, including extreme temperatures. Through noise-analysis and Monte Carlo (MC) simulations performed in a commercial 28nm Fully Depleted Silicon On Insulator (FDSOI) technology, the robustness to variations and extreme temperature ranges of the proposed symmetric 2-to-1 multiplexer design (mirror mux) with bias is demonstrated and compared to conventional 2-input NAND and NOR-based circuits. The linearity between temperature and bias makes this scheme easily applicable for programmable sensors in a variety of applications requiring environmental adaptability.

MS (Master of Science)
28nm FDSOI, energy harvesting, nanoscale CMOS, sub-threshold, wide temperature-range, ultra-low power
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