# Internet of Things: A Review on Theory Based Impedance Matching Techniques for Energy Efficient RF Systems

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## Abstract

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## 1. Introduction

## 2. Formal Expressions of the Power Gain in Typical RF Systems

#### 2.1. ABCD-Parameters Approach

#### 2.2. Transducer Gain

#### 2.3. Transmission Lines Approach

#### 2.4. Power Waves

## 3. Optimal Design of RF Systems Using an Analytical Approach

#### 3.1. Integration of the Transmission Line Parameters

#### 3.2. Integration of Matching Network Parameters

#### 3.3. RF Design Framework

## 4. Validation and Implementation of the Design Framework

#### 4.1. Validation of Theoretical Approaches

#### 4.2. Implementation of the Proposed Design Framework

## 5. Conclusions

## Funding

## Conflicts of Interest

## References

- Number of Internet of Things (IoT) Connected Devices Worldwide in 2018, 2025 and 2030. Available online: https://www.statista.com/statistics/802690/worldwide-connected-devices-by-access-technology/ (accessed on 30 March 2021).
- Big Data Analytics in the Smart Grid: Big Data Analytics, Machine Learning and Artificial Intelligence in the Smart Grid: Introduction, Benefits, Challenges and Issues, IEEE, United States, WorkingPaper, Nov. 2017, iEEE Smart Grid White Paper. Available online: https://smartgrid.ieee.org/images/files/pdf/big_data_analytics_white_paper.pdf (accessed on 30 March 2021).
- Tang, W.; Andoni, M.; Robu, V.; Flynn, D. Accurately forecasting the health of energy system assets. In Proceedings of the 2018 IEEE International Symposium on Circuits and Systems (ISCAS), Florence, Italy, 27–30 May 2018; pp. 1–5. [Google Scholar]
- Tang, W.; Roman, D.; Dickie, R.; Robu, V.; Flynn, D. Prognostics and health management for the optimization of marine hybrid energy systems. Energies
**2020**, 13, 4676. [Google Scholar] [CrossRef] - Barnes, M.; Brown, K.; Carmona, J.; Cevasco, D.; Collu, M.; Crabtree, C.; Crowther, C.; Djurovic, S.; Flynn, D.; Green, P.; et al. Technology Drivers in Windfarm Asset Management. Available online: https://researchportal.hw.ac.uk/en/publications/technology-drivers-in-windfarm-asset-management (accessed on 30 March 2021).
- Huynh, N.; Robu, V.; Flynn, D.; Rowland, S.; Coapes, G. Design and demonstration of a wireless sensor network platform for substation asset management. Cired Open Access Proc. J.
**2017**, 105–108. [Google Scholar] [CrossRef] - Fisher, M.; Collins, E.; Dennis, L.; Luckcuck, M.; Webster, M.; Jump, M.; Page, V.; Patchett, C.; Dinmohammadi, F.; Flynn, D.; et al. Verifiable self-certifying autonomous systems. In Proceedings of the 2018 IEEE International Symposium on Software Reliability Engineering Workshops (ISSREW), Memphis, TN, USA, 15–18 October 2018; pp. 341–348. [Google Scholar]
- Rana, M.M.; Xiang, W.; Wang, E.; Li, X.; Choi, B.J. Internet of things infrastructure for wireless power transfer systems. IEEE Access
**2018**, 6, 19295–19303. [Google Scholar] [CrossRef] - Gurjar, D.S.; Nguyen, H.H.; Tuan, H.D. Wireless information and power transfer for IoT applications in overlay cognitive radio networks. IEEE Internet Things J.
**2019**, 6, 3257–3270. [Google Scholar] [CrossRef] [Green Version] - Sheng, Z.; Mahapatra, C.; Zhu, C.; Leung, V.C.M. Recent advances in industrial wireless sensor networks toward efficient management in iot. IEEE Access
**2015**, 3, 622–637. [Google Scholar] [CrossRef] - Thingpark Market. Available online: https://market.thingpark.com/ (accessed on 30 January 2021).
- Daskalakis, S.N.; Goussetis, G.; Assimonis, S.D.; Tentzeris, M.M.; Georgiadis, A. A uW backscatter-morse-leaf sensor for low-power agricultural wireless sensor networks. IEEE Sensors J.
**2018**, 18, 7889–7898. [Google Scholar] [CrossRef] [Green Version] - Daskalakis, S.; Assimonis, S.D.; Kampianakis, E.; Bletsas, A. Soil moisture scatter radio networking with low power. IEEE Trans. Microw. Theory Tech.
**2016**, 64, 2338–2346. [Google Scholar] [CrossRef] - Daskalakis, S.N.; Assimonis, S.D.; Goussetis, G.; Tentzeris, M.M.; Georgiadis, A. The Future of Backscatter in Precision Agriculture. In Proceedings of the IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, Atlanta, GA, USA, 7–12 July 2019; pp. 647–648. [Google Scholar]
- Zhaksylyk, Y.; Halvorsen, E.; Hanke, U.; Azadmehr, M. Analysis of Fundamental Differences between Capacitive and Inductive Impedance Matching for Inductive Wireless Power Transfer. Electronics
**2020**, 3, 476. [Google Scholar] [CrossRef] [Green Version] - Monti, G.; Mastri, F.; Mongiardo, M.; Corchia, L.; Tarricone, L. Transducer gain maximization for a resonant inductive WPT link using relay resonators. In Proceedings of the 2018 IEEE MTT-S International Wireless Symposium (IWS), Chengdu, China, 6–10 May 2018; pp. 1–4. [Google Scholar]
- Vandelle, E.; Bui, D.H.N.; Vuong, T.; Ardila, G.; Wu, K.; Hemour, S. Harvesting ambient RF energy efficiently with optimal angular coverage. IEEE Trans. Antennas Propag.
**2019**, 67, 1862–1873. [Google Scholar] [CrossRef] - da Silva, E.F.; Gomes Neto, A.; Peixeiro, C. Fast and accurate rectenna design method. IEEE Antennas Wirel. Propag. Lett.
**2019**, 18, 886–890. [Google Scholar] [CrossRef] - Daskalakis, S.N.; Georgiadis, A.; Goussetis, G.; Tentzeris, M.M. A rectifier circuit insensitive to the angle of incidence of incoming waves based on a Wilkinson power combiner. IEEE Trans. Microw. Theory Tech.
**2019**, 67, 3210–3218. [Google Scholar] [CrossRef] - Assimonis, S.D.; Daskalakis, S.; Bletsas, A. Sensitive and efficient RF harvesting supply for batteryless backscatter sensor networks. IEEE Trans. Microw. Theory Tech.
**2016**, 64, 1327–1338. [Google Scholar] [CrossRef] [Green Version] - Assimonis, S.D.; Daskalakis, S.N.; Fusco, V.; Tentzeris, M.M.; Georgiadis, A. High efficiency RF energy harvester for iot embedded sensor nodes. In Proceedings of the 2019 IEEE International Symposium on Antennas and Propagation and USNC-URSI Radio Science Meeting, Atlanta, GA, USA, 7–12 July 2019; pp. 1161–1162. [Google Scholar]
- Assimonis, S.D.; Fusco, V. RF energy harvesting with dense rectenna-arrays using electrically small rectennas suitable for iot 5G embedded sensor nodes. In Proceedings of the 2018 IEEE MTT-S International Microwave Workshop Series on 5G Hardware and System Technologies (IMWS-5G), Dublin, Ireland, 30–31 August 2018; pp. 1–3. [Google Scholar]
- Couraud, B.; Deleruyelle, T.; Vauche, R.; Flynn, D.; Daskalakis, S.N. A low complexity design framework for nfc-rfid inductive coupled antennas. IEEE Access bf
**2020**, 8, 111. [Google Scholar] [CrossRef] - Charthad, J.; Dolatsha, N.; Rekhi, A.; Arbabian, A. System-level analysis of far-field radio frequency power delivery for mm-sized sensor nodes. IEEE Trans. Circuits Syst. Regul. Pap.
**2016**, 63, 300–311. [Google Scholar] [CrossRef] - Neubauer, A.; Hammes, M. A digital receiver architecture for Bluetooth in 0.25- μm CMOS technology and beyond. IEEE Trans. Circuits Syst. Regul. Pap.
**2007**, 54, 2044–2053. [Google Scholar] [CrossRef] - Oh, S.; Kim, S.; Ali, I.; Nga, T.T.K.; Lee, D.; Pu, Y.; Yoo, S.; Lee, M.; Hwang, K.C.; Yang, Y.; et al. A 3.9 mw bluetooth low-energy transmitter using all-digital PLL-based direct FSK modulation in 55 nm CMOS. IEEE Trans. Circuits Syst. Regul. Pap.
**2018**, 65, 3037–3048. [Google Scholar] [CrossRef] - Li, S.C.; Kao, H.-S.; Chen, C.-P.; Su, C.-C. Low-power fully integrated and tunable CMOS RF wireless receiver for ISM band consumer applications. IEEE Trans. Circuits Syst. Regul. Pap.
**2005**, 52, 1758–1766. [Google Scholar] [CrossRef] - Xu, K. Integrated silicon directly modulated light source using p-well in standard cmos technology. IEEE Sensors J.
**2016**, 16, 6184–6191. [Google Scholar] [CrossRef] - Shafiee, N.; Tewari, S.; Calhoun, B.; Shrivastava, A. Infrastructure circuits for lifetime improvement of ultra-low power IoT devices. IEEE Trans. Circuits Syst. Regul. Pap.
**2017**, 64, 2598–2610. [Google Scholar] [CrossRef] - Zeng, W.; Ren, Y.; Lam, C.; Sin, S.; Che, W.; Ding, R.; Martins, R.P. A 470-nA quiescent current and 92.7 control buck converter with seamless mode selection for IoT application. IEEE Trans. Circuits Syst. Regul. Pap.
**2020**, 1–14. [Google Scholar] [CrossRef] - Assimonis, S.; Fusco, S.; Georgiadis, A.; Samaras, T. Efficient and sensitive electrically small rectenna for ultra-low power RF energy harvesting. Sci. Rep.
**2018**, 8. [Google Scholar] [CrossRef] [Green Version] - Sheng, W.; Emira, A.; Sanchez-Sinencio, E. CMOS RF receiver system design: A systematic approach. IEEE Trans. Circuits Syst. Regul. Pap.
**2006**, 53, 1023–1034. [Google Scholar] [CrossRef] [Green Version] - Ivrlac, M.T.; Nossek, J.A. Toward a circuit theory of communication. IEEE Trans. Circuits Syst. Regul. Pap.
**2010**, 57, 1663–1683. [Google Scholar] [CrossRef] - Vasjanov, A.; Barzdenas, V. A methodology improving off-chip, lumped RF impedance matching network response accuracy. Electronics
**2018**, 7, 188. [Google Scholar] [CrossRef] [Green Version] - Rathod, V. A Review of Electric Impedance Matching Techniques for Piezoelectric Sensors, Actuators and Transducers. Electronics
**2019**, 2, 169. [Google Scholar] [CrossRef] [Green Version] - Thompson, M.; Fidler, J.K. Determination of the impedance matching domain of impedance matching networks. IEEE Trans. Circuits Syst. Regul. Pap.
**2004**, 51, 2098–2106. [Google Scholar] [CrossRef] - Chappidi, C.R.; Sengupta, K. Globally optimal matching networks with lossy passives and efficiency bounds. IEEE Trans. Circuits Syst. Regul. Pap.
**2018**, 65, 257–269. [Google Scholar] [CrossRef] - Wu, Y.; Jiao, L.; Liu, Y. Comments on ’novel dual-band matching network for effective design of concurrent dual-band power amplifiers. IEEE Trans. Circuits Syst. Regul. Pap.
**2015**, 62, 2361–2363. [Google Scholar] [CrossRef] - Sjoblom, P.; Sjoland, H. An adaptive impedance tuning CMOS circuit for ism 2.4-ghz band. IEEE Trans. Circuits Syst. Regul. Pap.
**2005**, 52, 1115–1124. [Google Scholar] [CrossRef] - Hur, B.; Eisenstadt, W.; Melde, K. Testing and validation of adaptive impedance matching system for broadband antenna. Electronics
**2019**, 8, 1055. [Google Scholar] [CrossRef] [Green Version] - Bodway, G. Two port power flow analysis using generalized scattering parameters. In Microwave Journal; Horizon House Publications: Norwood, MA, USA, 1967. [Google Scholar]
- Pozar, D.M. Microwave engineering; Wiley: Hoboken, NJ, USA, 2012; ISBN 978-0-470-63155-3. [Google Scholar]
- Kurokawa, K. Power waves and the scattering matrix. IEEE Trans. Microw. Theory Tech.
**1965**, 13, 194–202. [Google Scholar] [CrossRef] [Green Version] - Finkenzeller, K. RFID Handbook: Fundamentals and Applications in Contactless Smart Cards, Radio Frequency Identification and near-Field Communication; John Wiley and Sons: Hoboken, JK, USA, 2010. [Google Scholar]
- Frickey, D.A. Conversions between s, z, y, h, abcd, and t parameters which are valid for complex source and load impedances. IEEE Trans. Microw. Theory Tech.
**1994**, 42, 205–211. [Google Scholar] [CrossRef] - Baudin, P. Wireless transceiver architecture: Bridging RF and digital communications; Wiley: Hoboken, NJ, USA, 2014; ISBN 978-1-118-87482-0. [Google Scholar]
- Sadiku, M. Elements of Electromagnetics; Oxford University Press: Oxford, UK, 2014. [Google Scholar]
- Denlinger, E.J. Losses of microstrip lines. IEEE Trans. Microw. Theory Tech.
**1980**, 28, 513–522. [Google Scholar] [CrossRef] - Chang, K. Handbook of Microwave and Optical Components, Microwave Passive and Antenna Components; ser. Handbook of Microwave and Optical Components; Wiley: Hoboken, NJ, USA, 1989. [Google Scholar]
- Matthaei, G. Microwave Filters, Impedance-Matching Networks, and Coupling Structures; McGraw-Hill: New York, NY, USA, 1964. [Google Scholar]
- Ferrero, A.; Pirola, M. Harmonic load-pull techniques: An overview of modern systems. IEEE Microw. Mag.
**2013**, 14, 116–123. [Google Scholar] [CrossRef] - Angelotti, A.M.; Gibiino, G.P.; Nielsen, T.S.; Schreurs, D. Santarelli, A. Wideband active load-pull by device output match compensation using a vector network analyzer. IEEE Trans. Microw. Theory Tech.
**2021**, 69, 874–886. [Google Scholar] [CrossRef] - Couraud, B.; Deleruyelle, T.; Kussener, E.; Vauche, R. Real-time impedance characterization method for rfid-type backscatter communication devices. IEEE Trans. Instrum. Meas.
**2018**, 67, 288–295. [Google Scholar] [CrossRef] - Michalewicz, Z.; Schoenauer, M. Evolutionary algorithms for constrained parameter optimization problems. Evol. Comput.
**1996**, 4, 1–32. [Google Scholar] [CrossRef] - Cihangir, A.; Panagamuwa, C.J.; Whittow, W.G.; Jacquemod, G.; Gianesello, F.; Pilard, R.; Luxey, C. Dual-band 4G eyewear antenna and sar implications. IEEE Trans. Antennas Propag.
**2017**, 65, 2085–2089. [Google Scholar] [CrossRef] [Green Version] - Zheng, Y.F.; Sun, G.H.; Huang, Q.K.; Wong, S.W.; Zheng, L.S. Wearable PIFA antenna for smart glasses application. In Proceedings of the 2016 IEEE International Conference on Computational Electromagnetics (ICCEM), Guangzhou, China, 23–25 February 2016; pp. 370–372. [Google Scholar]

**Figure 1.**Overall architecture of an IoT end point and the focus of this study in red: the design of the line and matching network.

**Figure 4.**Flow graph for the RF system described in Figure 2.

**Figure 5.**Description of the considered microstrip as an example, where the geometrical parameters to be optimized have been highlighted (width, length and thickness).

**Figure 6.**T-Shaped matching network corresponding to (41).

**Figure 11.**Final design for the Bluetooth system design meeting the geometric constraints, and associated S-parameters.

**Table 1.**List and comparison of the different power gain formal expressions described in this paper.

Approach Name Name | Strengths | Weakness of Usual Use Case |
---|---|---|

ABCD parameters | Multiplication of matrices that depend on system’s impedances | None |

Transducer gain | Expressed as a function of scattering parameters | Does not include transmission line |

Transmission lines theory | Simple formula models the effects of the line | Expression depends on unknown parameters (${V}_{0}^{i}$ in (24)) |

Power waves | Simple formula | Does not include transmission line nor matching network |

Parameter | Value | Unit | Parameter | Value | Unit |
---|---|---|---|---|---|

${Z}_{g}$ | 50 | $\Omega $ | d | 1.5 | mm |

$Re\left(\right)open="\{"\; close="\}">{Z}_{L}$ | 50 | $\Omega $ | ${L}_{a}$ | 1 | nH |

w | 2.3 | mm | ${C}_{p}$ | 1 | pF |

h | 1.6 | mm | ${C}_{L}$ | 10 | pF |

L | 67 | mm | ${\epsilon}_{r}$ | 4.4 |

Parameter | Value | Unit | Parameter | Value | Unit |
---|---|---|---|---|---|

${Z}_{g}$ | 75 | $\Omega $ | ${L}_{a}$ | 5.7 | nH |

$Re\left(\right)open="\{"\; close="\}">{Z}_{L}$ | 72 | $\Omega $ | ${C}_{p}$ | 0.6 | pF |

w | 2.1 | mm | ${C}_{L}$ | 0.1 | pF |

h | 1.6 | mm | ${\epsilon}_{r}$ | 9.6 | |

L | 37 | mm |

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## Share and Cite

**MDPI and ACS Style**

Couraud, B.; Vauche, R.; Daskalakis, S.N.; Flynn, D.; Deleruyelle, T.; Kussener, E.; Assimonis, S.
Internet of Things: A Review on Theory Based Impedance Matching Techniques for Energy Efficient RF Systems. *J. Low Power Electron. Appl.* **2021**, *11*, 16.
https://doi.org/10.3390/jlpea11020016

**AMA Style**

Couraud B, Vauche R, Daskalakis SN, Flynn D, Deleruyelle T, Kussener E, Assimonis S.
Internet of Things: A Review on Theory Based Impedance Matching Techniques for Energy Efficient RF Systems. *Journal of Low Power Electronics and Applications*. 2021; 11(2):16.
https://doi.org/10.3390/jlpea11020016

**Chicago/Turabian Style**

Couraud, Benoit, Remy Vauche, Spyridon Nektarios Daskalakis, David Flynn, Thibaut Deleruyelle, Edith Kussener, and Stylianos Assimonis.
2021. "Internet of Things: A Review on Theory Based Impedance Matching Techniques for Energy Efficient RF Systems" *Journal of Low Power Electronics and Applications* 11, no. 2: 16.
https://doi.org/10.3390/jlpea11020016