On-Chip Solar Energy Harvester and PMU With Cold Start-Up and Regulated Output Voltage for Biomedical Applications

Cabello, D.; Ferro, E.; Pereira-Rial, O.; Martinez-Vazquez, Beatriz; Brea, V.M.; Carrillo, Juan M.; López, P.

doi:10.1109/tcsi.2019.2944252

Cited by 25 publications

(16 citation statements)

References 27 publications

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“…The Internet of Things (IoT) enables intelligent monitoring and management in many applications. This includes environmental and infrastructure monitoring as well as industrial and biomedical applications [1]- [4]. In healthcare, implantable or wearable wireless sensor network (WSN) nodes can be used to constantly monitor vital signs such as pulse, blood pressure, oxygen saturation, and ECG signals of persons at risk such as the elderly [5], [6].…”

Section: Introductionmentioning

confidence: 99%

“…Wearable and implantable WSN nodes are offgrid and small-sized. For example, the implantable intraocular device in [1] measures 5mm x 5mm x1.5mm. The required small form-factor results in limited-capacity batteries that would require periodic replacement.…”

Section: Introductionmentioning

confidence: 99%

“…For example, a 2.6mm x 3mm solar cell may produce 20nW-200µW depending on illuminance [18]. This wide variation is especially challenging for implantable devices located in body areas exposed to light, such as inside the eye or under the skin [1], [8]. Second, WSN nodes are deployed in harsh environments and energy must be harvested from ultra-low power levels.…”

Section: Introductionmentioning

confidence: 99%

“…Second, WSN nodes are deployed in harsh environments and energy must be harvested from ultra-low power levels. In implantable biomedical applications, a 1mm 2 solar cell harvests less than 8.3µW [1]. In biological sensing applications, ambient power levels can be in the pW to nW range due to quiet, dark, and cold environments [18].…”

Section: Introductionmentioning

confidence: 99%

“…In [9], MPPT overhead power consumption is reduced by utilizing an inherent feedback loop between the CP and the oscillator to eliminate some MPPT circuit blocks and sensors. In [1] and [20], twodimensional (2D) MPPT tunes the frequency and the voltage conversion ratio to achieve good PCE at multiple input voltages. In the MPPT techniques above, the reported peak efficiency occurs at a fixed, specific input/output power level and continues to decrease elsewhere.…”

Section: Introductionmentioning

confidence: 99%

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An Input Power-Aware Efficiency Tracking Technique With Discontinuous Charging for Energy Harvesting Applications

2020

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This paper proposes a discontinuous charging technique for switched-capacitor converters that improves the power conversion efficiency (PCE) at low power levels and extends the input power harvesting range at which high PCE is achievable. Discontinuous charging delivers current to energy storage only during clock non-overlap time. This enables tuning of the output current to minimize converter losses based on the available input power. Based on this fundamental result, an input power-aware, two-dimensional efficiency tracking technique for Wireless Sensor Network (WSN) nodes is presented. In addition to conventional switching frequency control, clock non-overlap time control is introduced to adaptively optimize PCE according to the sensed ambient power levels. The proposed technique is designed and simulated in 90nm CMOS with post-layout extraction. Under the same input and output conditions, the proposed system maintains at least 45% PCE at 4µW input power, as opposed to a conventional continuous system which requires at least 18.7µW to maintain the same PCE. Therefore, the input power harvesting range is extended by 1.5x. The technique is applied to a wearable WSN implementation utilizing the IEEE 802.15.4-compatible GreenNet communications protocol. This allows the node to meet specifications and achieve energy autonomy when deployed in environments where the input power is 49% lower than what is required for conventional operation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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An Input Power-Aware Efficiency Tracking Technique With Discontinuous Charging for Energy Harvesting Applications

2020

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A wide input voltage range, high power supply rejection low‐dropout regulator with a closed‐loop charge pump for sensor front‐end circuits

Niu

Lai

Wang

2023

Circuit Theory & Apps

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SummaryThis paper presents a low dropout regulator (LDO) with a wide input voltage range and high power supply rejection (PSR) for Hall sensor front‐end circuits, which is fabricated with a 0.18 μm BCD process. A topology in which a closed‐loop charge pump biases the gate of two‐stage cascode NMOS pass transistors is proposed to increase immunity to electromagnetic interference (EMI) capability for automotive applications. Furthermore, a power‐down protection circuit is proposed to maintain the reliability of the system, and a novel implementation of the charge pump unit is presented to improve the influence of the body effect. Detailed derivation regarding the analyses of the simplified small‐signal model of the closed‐loop charge pump, the loop stability, and the PSR at various frequency bands is given. Simulation and measurement results show that the proposed LDO can operate with the input voltage from 5 to 40 V, providing up to 60 mA current drive capability, and its minimum operating voltage is 2.5 V with a 10 mA load capacity. Moreover, results verify that measured PSR is better than −45 dB at 1.5 kHz, and measured PSR is better than −30 dB at 15 MHz. The results confirm that the obtained parameters of line and load regulations are significantly improved to 1.86 mV/V and 1.75 mV/mA, respectively.

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Introduction

Álvarez-Carulla¹,

Colomer‐Farrarons²,

Català³

2022

Self-Powered Energy Harvesting Systems for Health Supervising Applications

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On-Chip Solar Energy Harvester and PMU With Cold Start-Up and Regulated Output Voltage for Biomedical Applications

Cited by 25 publications

References 27 publications

An Input Power-Aware Efficiency Tracking Technique With Discontinuous Charging for Energy Harvesting Applications

An Input Power-Aware Efficiency Tracking Technique With Discontinuous Charging for Energy Harvesting Applications

A wide input voltage range, high power supply rejection low‐dropout regulator with a closed‐loop charge pump for sensor front‐end circuits

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