Theoretical Energy-Conversion Efficiency for Energy-Harvesting Circuits Under Power-Optimized Waveform Excitation

Valenta, Christopher R.; Morys, Marcin M.; Durgin, Gregory D.

doi:10.1109/tmtt.2015.2417174

Cited by 83 publications

(60 citation statements)

References 15 publications

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“…Fig. 11 shows that when K is small, as channel fluctuations contribute to v out , Randomized CHE Max-Min can be outperformed by 10 The vector pq is an optimization variable of problem (48), defined below (33) and related to the fraction of transmit power allocated for user q.…”

Section: Max-min Algorithms Under the Eirp Constraintmentioning

confidence: 99%

“…Although most off-the-shelf rectifier models in the context of microwave theory are able to provide insights into the accurate rectification process, non-closed forms or highly complex structures in these models [9], [10] make it hard to derive efficient algorithms for WPT. By contrast, [11] built a simplified (but inaccurate [8], [12], [13]) model by truncating the Taylor expansion of the Shockley diode equation to the 2nd-order term, where the rectenna DC output current is linearly proportional to the average incident RF power.…”

Section: Introductionmentioning

confidence: 99%

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Large-Scale Multiantenna Multisine Wireless Power Transfer

Huang

Clerckx

2017

IEEE Trans. Signal Process.

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Abstract-Wireless Power Transfer (WPT) is expected to be a technology reshaping the landscape of low-power applications such as the Internet of Things, RF identification (RFID) networks, etc. To that end, multi-antenna multi-sine waveforms adaptive to the Channel State Information (CSI) have been shown to be a promising building block of WPT. However, the current design is computationally too complex to be applied to large-scale WPT, where the transmit signal is sent across a large number (tens) of antennas and frequencies. In this paper, we derive efficient singleuser and multi-user algorithms based on a generalizable optimization framework, in order to design transmit waveforms that maximize the weighted-sum/minimum rectenna DC output voltage. The study highlights the significant effect of the nonlinearity introduced by the rectification process on the design of waveforms in single/multi-user systems. Interestingly, in the single-user case, the optimal spatial domain beamforming, obtained prior to the frequency domain power allocation optimization, turns out to be Maximum Ratio Transmission (MRT). On the contrary, in the general multi-user weighted sum criterion maximization problem, the spatial domain beamforming optimization and the frequency domain power allocation optimization are coupled. Assuming channel hardening, low-complexity algorithms are proposed based on asymptotic analysis, to maximize the two criteria. The structure of the asymptotically optimal spatial domain precoder can be found prior to the optimization. The performance of the proposed algorithms is evaluated. Numerical results confirm the inefficiency of the linear model-based design for the single and multi-user scenarios. It is also shown that as nonlinear modelbased designs, the proposed algorithms can benefit from an increasing number of sinewaves at a computational cost much lower than the existing method. Simulation results highlight the significant benefits of the large-scale WPT architecture to boost the end-to-end power transfer efficiency and the transmission range.

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Section: Max-min Algorithms Under the Eirp Constraintmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Large-Scale Multiantenna Multisine Wireless Power Transfer

Huang

Clerckx

2017

IEEE Trans. Signal Process.

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“…Proper harmonic termination can lead to a maximum theoretical efficiency of 100% [7], [26]. Recently theoretical limits of rectifier efficiency under power optimized waveform input signals were studied [11].…”

Section: Theoretical Analysismentioning

confidence: 99%

“…In earlier works, the rectifier efficiency was studied in the case of two-tone signals with different tone frequency separation [5]. The use of power optimized waveforms [10], [11] or multi-tone signals [12], [13] was investigated and it was shown that signals with high peakto-average power ratio (PAPR) may lead to a higher RF-dc conversion efficiency compared to a continuous wave (CW) signal with the same average power. Furthermore, the performance of rectifier circuits under randomly modulated signals has been evaluated experimentally in [14]- [18].…”

mentioning

confidence: 99%

RF Energy Harvesting From Multi-Tone and Digitally Modulated Signals

Bolos

Blanco

Collado

et al. 2016

IEEE Trans. Microwave Theory Techn.

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This paper presents the design of an RF energyharvesting circuit when excited by signals with a time-varying envelope such as multi-tone signals or digitally modulated signals with random modulation. The input matching network and the output load of a rectifier circuit are simultaneously optimized using harmonic balance in order to maximize its RF-dc conversion efficiency. This paper focuses on identifying the optimum load value, which corresponds to maximum efficiency for different types of input signals. The efficiency curves versus the load value show a single optimum efficiency point, which is a different for signals with a time-varying envelope and continuous wave (CW) signals. Specifically, for the series diode rectifier that was considered, the optimal load shifts to larger values as the signal peak-to-average-power-ratio (PAPR) increases compared to a CW signal with the same average power. As a result, for certain load values a signal with a time-varying envelope can result in a larger efficiency value than a CW signal. The peak efficiency value does not necessarily improve by using a signal with a time-varying envelope. A UHF rectifier prototype is built and its performance is evaluated experimentally showing good agreement with simulation.

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“…Although some broadband rectifier has been presented in the literature, it is noted that the proposed optimization is made for single‐frequency rectifier. In addition, earlier attempts have optimized the signal waveform or modulation schemes to maximize conversion efficiency, but this work selects continuous sinusoidal wave for the generality.…”

Section: Introductionmentioning

confidence: 99%

Theoretical limits of rectifying efficiency for low-power wireless power transfer

Chen

Chiu

2017

Int J RF Microw Comput Aided Eng

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The theoretical limits of power conversion efficiency for near‐field wireless power transfer were derived in recent years, but the maximum achievable efficiency for low‐power and far‐field powering has not yet been characterized. In this paper, we derive the performance limits of rectifiers using diodes for input power ranging from −20 dBm to 0 dBm. These theoretical limits are verified via measurement and simulation, and experimental performance data from the literature are extracted to validate the established maximum efficiency. Moreover, we propose design guidelines to achieve such performance limits, clarifying the method for optimizing the rectifier circuitry and the associated parameters. We further show potential approaches for the enhancement of maximum conversion efficiency via analyzing the loss parameters of Schottky diodes. This work thus establishes the performance benchmark of low‐power rectifiers and provides useful guidelines for future rectenna development.

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Theoretical Energy-Conversion Efficiency for Energy-Harvesting Circuits Under Power-Optimized Waveform Excitation

Cited by 83 publications

References 15 publications

Large-Scale Multiantenna Multisine Wireless Power Transfer

Large-Scale Multiantenna Multisine Wireless Power Transfer

RF Energy Harvesting From Multi-Tone and Digitally Modulated Signals

Theoretical limits of rectifying efficiency for low-power wireless power transfer

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