Low Power Internet Of Things Applications Research Articles

A 8.1-nW, 4.22-kHz, −40–85 °C relaxation oscillator with subthreshold leakage current compensation and forward body bias buffer for low power IoT applications

This paper presents a relaxation oscillator (RxO) utilizing subthreshold transistor leakage current compensation (SLC) technology to expand the operating range from 70 °C to 85 °C at high temperatures. The compensated RxO outperforms the uncompensated counterpart by 25 times for temperature coefficient (TC). Additionally, forward body bias (FBB) technology optimizes the digital buffer delay with temperature drift at low supply voltage, extending the oscillator’s low-temperature range from −20 °C to −40 °C. Fabricated in a 65 nm CMOS process, the oscillator consumes a mere 8.1 nW at a 0.4 V supply voltage. At room temperature, it operates at 4.22 kHz with an energy efficiency of 1.92 nW/kHz. The oscillator demonstrates a temperature coefficient (TC) of 114.01 ppm/°C within the range of −40 °C to 85 °C, rendering it a prospective choice for low-power Internet of Things (IoT) applications.

A 13.5-nA Quiescent Current LDO With Adaptive Ultra-Low-Power Mode for Low-Power IoT Applications

This brief presents a low-dropout regulator (LDO) for power-efficient Internet of Things (IoT) devices. When IoT devices are in low-power standby mode, the proposed LDO senses the load current and enters an ultra-low-power mode to enable an extremely low-power system. The proposed LDO alternates between two modes of operation. One is the ultra-low-power mode in which the core circuit of the LDO is turned off to save power, and the other is an active mode in which all circuit components are on. The successful operation of the proposed scheme is demonstrated by implementing and measuring silicon LDO chips, resulting in an extremely low-quiescent current of 13.5 nA and a superior figure-of-merit (FOM).

Prospects and Challenges of Different Geometries of TFET Devices for IoT Applications

Background: The applications based on IoT are nearly boundless, and the integration of the cyber world and the physical world can be done effortlessly. TFET Based IoT applications may be the future alternative to existing MOSFET-based IoT because of the faster switching speed of TFET devices. Objectives: Prospects and challenges in a simulation study of different Geometries of TFET devices for IoT Applications. Methods: In this manuscript, the detailed study of IoT evolution, IoT applications and challenges faced by IoT industries based on different TFET geometries have been elaborated and analyzed. Results: The Internet of Things (IoT) is a new prototype that provides a set of new services for new-generation technological innovations. IoT has seized the entire technological world as it can be used in every application like health, security, environmental and biomedical applications etc. The semiconductor TFET devices operating at low supply voltage and consuming the least power are most suitable for IoT applications. The devices like digital inverter, memory, adiabatic circuit, and different shaped TFET are explained as well as compared in tabular form thoroughly Conclusion: In next-generation devices, TFET can be widely used for low-power IoT applications because of the superior switching characteristics performance.

An Optimized Energy Harvesting Circuit for Low-Power IoT Applications

The concept and development of an independent energy harvesting mechanism functioning intermittently are described in this paper. A power management circuit (PMC) that is self-regulating, an energy scavenging module, a circuit for charging batteries, as well as an electronic load are all a component of the system that has been proposed. This proposed circuit is designed to attain a fixed output power with a diverse input range. In the unavailability of an additional voltage supply, the PMC can react, maintain, and smartly control the electronic load's power supply. The self-powered energy accumulating technique is expected to be used in situations when supplied power is inadequate to drive the load properly, such as Internet of Things (IoT) applications. IoT is a dispersed architecture of reduced-power, limited-storage, lightweight, and nodes that are adaptive. The majority of embedded IoT devices and low-power IoT sensors are driven by short-life batteries that must be replaced every few years. This procedure is expensive and efficient energy regulation could be critical in enabling energy savings for connecting IoT devices. Experiments with the proposed PMC show that the voltage stored in the capacitor remained mostly fixed at 3.3V at widely diverse inputs that vary from 850mV to 4V. At 3.5V input voltage, a peak efficiency of 88.67% is achieved while the load resistance considered is 230Ω.

2.4-GHz Bluetooth Low Energy Receiver Employing New Quadrature Low-Noise Amplifier for Low-Power Low-Voltage IoT Applications

In this article, a 2.4-GHz Bluetooth low-energy (BLE) receiver employing a new quadrature low-noise amplifier (LNA) is presented for low-power low-voltage Internet of Things (IoT) applications. The proposed quadrature LNA consists of a common-source (CS) amplifier with inductive degeneration, an active-type poly-phase filter (PPF), and an LC tank. The proposed active-type PPF between the CS amplifier and the LC tank provides quadrature generation, and the CS amplifier determines and optimizes the overall LNA performance parameters. Moreover, the proposed active-type PPF shares the dc bias current with the CS amplifier, thereby eliminating the necessity for additional current consumption. The implemented BLE receiver is composed of the quadrature LNA, a $G_{m}$ -stage, a double-balanced current-mode passive mixer, a transimpedance amplifier, and an active- RC complex bandpass filter. The proposed design was fabricated in a 65-nm CMOS process and mainly characterized in the BLE operating frequency bands. The receiver achieves a noise figure of 8.2 dB, a conversion gain of 49.5 dB, an image rejection ratio of more than 33 dB, and an IIP3 of −25.75 dBm. The active die area of the implemented receiver is 1.16 mm2, and it draws a bias current of 2.7 mA from a nominal supply voltage of 0.8 V.

RAMTEL: Robust Acoustic Motion Tracking Using Extreme Learning Machine for Smart Cities

Motion tracking is attractive in what concerns a smart city environment, where citizens have to interact with Internet of Things (IoT) infrastructures spread all around one particular city. Motion tracking is important for smart services and location-based services in smart cities, since it provides natural ways for users to interact with the IoT infrastructures, such as the ability to recognize of a wide range of hand motion in real-time. Compared with dedicated hardware devices, ubiquitous devices with reliable speakers and microphones can be developed to achieve cheap acoustic-based motion tracking, which is appropriate for low-power and low-cost IoT applications. However, for complex urban environments, it is very difficult for acoustic-based methods to achieve accurate motion tracking due to multipath fading and limited sampling rate at mobile devices. In this paper, a new parameter called multipath dispersion vector (MDV) is proposed to estimate and mitigate the impact of multipath fading on received signals using extreme learning machine. Based on MDV, a robust acoustic motion tracking (RAMTEL) method is proposed to calculate the moving distance based on the phase change of acoustic signals, and track the corresponding motion in 2-D plane by using multiple speakers. The method is then proposed and implemented on standard Android smartphones. Experiment results show, without any specialized hardware, RAMTEL can achieve an impressive millimeter-level accuracy for localization and motion tracking applications in multipath fading environments. Specifically, the measurement errors are less than 2 and 4 mm in 1-D and 2-D scenarios, respectively.

A Residual Phase Noise Compensation Method for IEEE 802.15.4 Compliant Dual-Mode Receiver for Diverse Low Power IoT Applications

The Internet of Things (IoT) with its plethora of applications brings up new challenges in optimizing power consumption, error performance, latency, and throughput in its communication devices. Recently, there has been increasing necessity of reconfigurable and multistandard transceivers in order to bring adaptability in the IoT devices to suit the nature of the application and satisfy the aforementioned performance metrics as well. In this paper, we focus on the efficient design of receivers compliant with IEEE 802.15.4 which is a prominent protocol for low power IoT applications. We propose a robust phase noise compensation method which efficiently removes the residual phase noise remaining after the coarse frequency offset compensation due to direct-sequence spread spectrum operation on large packets. We also propose a dual-mode receiver using the proposed compensation method and showcase its ability to cater to the diverse nature of IoT applications. The detailed architecture of proposed dual-mode receiver is presented along with its FPGA prototyping and ASIC implementation. We have analyzed overall power consumption by the proposed dual-mode receiver considering the packet error rate and retransmission scenario. The results show that the proposed receiver saves significant energy consumption by changing its mode in favorable channel environments.

Wake-Up Radio for Low-Power Internet of Things Applications: An Alternative Method to Coordinate Data Transfers

Reductions in wireless-sensor-node form factor and cost have enabled new applications for remote sensing in a variety of areas, such as grid infrastructure, building automation, medicine, factory automation and control, and automobiles. The projected number of sensor nodes is so large that battery replacement for all of them is impractical. Therefore, for market success, power consumption must be low enough that power can be supplied through energy harvesting or a small battery capable of lasting the lifetime of the sensor node.

Rotational energy harvesting using bi-stability and frequency up-conversion for low-power sensing applications: Theoretical modelling and experimental validation

Abstract Kinetic energy harvesting has drawn great attention in the past decade, but low-frequency and broadband operation is still a big issue which impedes this technology to be widely deployed in low-power Internet of Things applications. In this paper, theoretical modelling and experimental validation of a rotational harvester with bi-stability and frequency up-conversion is presented for harnessing low-frequency kinetic energy with a wide bandwidth. Piezoelectric transduction was adopted to convert the rotational kinetic energy into electricity. Distributed-parameter modelling was employed for analyzing the electromechanical dynamics of the bistable piezoelectric beam. Bistable and frequency up-converting behaviours were considered in the theoretical model by introducing two external input magnetic forces. Different oscillating modes were analyzed, showing the variation of power generation capability under different modes, and the advantage of operating in the periodic double-well mode. From the potential well study, we got a conclusion that for the same input magnetic force, periodic double-well mode is capable of achieving a larger vibration amplitude compared to a harvester without bi-stability. Asymmetric potential well shapes were investigated. This asymmetric shape provides a way to stabilize the initiation position of the beam for each plucking cycle, and eventually to stabilized the output. Key design factors to control the oscillating modes were studied, providing a guideline for future design. An experimental study was conducted to verify the theoretical results. A close match was achieved. This bistable harvester demonstrated a significant improvement (up to 2 × ) compared to a harvester without bi-stability over a wide bandwidth (from 1 to 11 Hz) at low frequencies, when operating in the periodic double-well mode. This paper presents a detailed theoretical model and in-depth analysis of a bistable frequency up-converting harvester, providing a fundamental understanding and guidance for low-frequency broadband energy harvester design.

Multiradix Trivium Implementations for Low-Power IoT Hardware

The integration of lightweight symmetric encryption is becoming increasingly widespread in very low-power Internet of Things applications, with the rapid emergence of very low energy block and stream ciphers in portable and wireless systems. Trivium is one of the lightweight stream ciphers shortlisted for the hardware profile of the eSTREAM project. This paper describes low-power multiradix Trivium implementations based on the use of parallelization techniques to reduce dynamic power consumption. The low-power Trivium designs were implemented and characterized in TSMC 90 nm to compare area resources and power reduction. The implementation results show that our proposed designs offer dynamic power savings of 31%-45% with radix-1 and radix-2 when compared with the standard Trivium, and 15% with radix-8. There is no improvement, however, with radix-16.