# 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

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**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 |

$Re\left\{{Z}_{L}\right\}$ | 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 |

$Re\left\{{Z}_{L}\right\}$ | 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