Analysis and design of UHF and millimetre wave radio frequency identification

Radio frequency identification (RFID) is an asymmetric radio protocol, where uplink communication (from transponder to reader) is implemented with backscattering modulation. The idea was first demonstrated in the 1940's. One of the first consumer applications of RFID was access control, and key cards based on an inductive near field coupling are widely used even today. The introduction of Schottky diodes to CMOS processes enabled passive RFID, i.e. transponders without a battery, at ultra high frequencies (UHF) with reasonable cost and read range in the end of 1990's. This has opened up new applications and inspired new research on RFID. This thesis studies the radio frequency (RF) components and general RF phenomena in RFID at UHF and millimetre waves. The theoretical analysis of the radio path reveals that the read range of a passive UHF system is ideally limited by the downlink, i.e. the power transfer from reader to the transponder. However, the architecture of the reader RF front end is critical, because the transmitted signal may couple a significant amount of noise to the receiver, overpowering the faint reflection from the transponder. In the thesis, two adaptive RF front ends are introduced to eliminate the noise coupling from the transmitter. One of the most critical problems with UHF RFID has been the detuning of transponder antennas on different mounting platforms. The detuning may significantly diminish the read range of the transponder, especially on metal surfaces. In this thesis, two backscattering-based measurement techniques for the transponder antennas are presented. The detuning effect has been studied using these measurement techniques, and a platform tolerant antenna is introduced. RFID at millimetre waves enables miniaturisation of the reader antenna, and widening the data bandwidth over short distances. This could be used to access wirelessly mass memories with wide data bandwidth. A semi-passive or active transponder could communicate, e.g., with automotive radars. The millimetre wave identification (MMID) has been theoretically studied and experimentally verified at 60 GHz

A Novel Long-Range Passive UHF RFID System over Twisted-pair Cable

Radio Frequency Identification (RFID) is one of the most representative, rapidly growing, and highly extendable technologies, which uses electromagnetic waves in accordance with specific communications standards and regulations to identify, track, or even localise desired objects. However, due to its high cost, limited read range, and uncertain reliability, its adoption still lags, especially in large-scale organisations. Even though an RFID distributed antenna system (DAS) can greatly improve the detection range and read rate of a single reader when system uses different combinations of antenna states with frequency and phase hopping, the lossy and heavy coaxial cables between reader and antennas still limits the system coverage and design flexibility for wide-area passive UHF RFID applications. In order to develop a cost-efficient and flexibly-installed passive RFID DAS, a novel large-range passive UHF RFID system over twisted-pair cable is proposed in this dissertation. This new system consists of one baseband central controller and one antenna subsystem, connected by a commonly used twisted-pair cable. It is shown that transmitting/receiving low frequency baseband signals over a twisted-pair cable can significantly reduce cable attenuation and extend the communication distance. A simulation is conducted to demonstrate that frequency and phase hopping can also be remotely controlled to fit this system structure by slightly varying the frequency or phase of the input reference signal of the frequency synthesis system. The features of twisted-pair cable in terms of its low cost, light weight, and bend radius greatly improve the design and installation flexibility of an RFID system. The implemented system is designed based on the ISO 18000-6C and EPC Class 1 Generation 2 standards, and can operate according to FCC (902-928 MHz) and ETSI (865-868MHz) regulations. The results of the measurement show the reader can achieve a sensitivity of - 94.5 dBm over 30 m Cat5e cable, and its sensitivity can still remain at around -94.2 dBm over 150 m Cat5e cable. The experimental results of tag detection show that the passive tags can be successfully detected over a 6 m wireless range following a 300 m of twisted-pair cable between the central controller and antenna. This detection range cannot be achieved by existing commercial RFID systems. Since the transmission and reception in a RFID system are simultaneous, finite isolation of the circulator/directional coupler and environmentally dependent reflection ratio of the antenna lead to serious leakage problems. Leakage can directly cause sensitivity degradation due to saturation of the RF components. A fast leakage suppression block is developed in efforts to solve this problem. Measurements show that this new canceller can deliver an average suppression of 36.9 dB, and this excellent performance remains when the system uses frequency hopping. With help of an improved scanning algorithm, this canceller can find its optimal status within 38 ms, and this settling time is short enough for most commercial RFID readers. By reducing the number of voltage samples taken, the convergence time can be further improved. To fully investigate this new passive UHF RFID system value, a comparison study between the new system and a commercial system is conducted. This new automatic passive UHF RFID system is confirmed to deliver high performance long-range passive tag detection. Particular advantages are shown in the fast tag read rate and capability of uplink SNR improvement. This novel system is also superior to conventional RFID systems in terms of link distance, link cost, and installation flexibility

Sistemas eficientes de transmissão de energia sem-fios e identificação por radiofrequência

Doutoramento em Engenharia EletrotécnicaIn the IoT context, where billions of connected objects are expected to be ubiquitously deployed worldwide, the frequent battery maintenance of ubiquitous wireless nodes is undesirable or even impossible. In these scenarios, passive-backscatter radios will certainly play a crucial role due to their low cost, low complexity and battery-free operation. However, as passive-backscatter devices are chiefly limited by the WPT link, its efficiency optimization has been a major research concern over the years, gaining even more emphasis in the IoT context. Wireless power transfer has traditionally been carried out using CW signals, and the efficiency improvement has commonly been achieved through circuit design optimization. This thesis explores a fundamentally different approach, in which the optimization is focused on the powering waveforms, rather than the circuits. It is demonstrated through theoretical analysis, simulations and measurements that, given their greater ability to overcome the built-in voltage of rectifying devices, high PAPR multi-sine (MS) signals are capable of more efficiently exciting energy harvesting circuits when compared to CWs. By using optimal MS signals to excite rectifying devices, remarkable RF-DC conversion efficiency gains of up to 15 dB with respect to CW signals were obtained. In order to show the effectiveness of this approach to improve the communication range of passive-backscatter systems, a MS front-end was integrated in a commercial RFID reader and a significant range extension of 25% was observed. Furthermore, a software-defined radio RFID reader, compliant with ISO18000-6C standard and with MS capability, was constructed from scratch. By interrogating passive RFID transponders with MS waveforms, a transponder sensitivity improvement higher than 3 dB was obtained for optimal MS signals. Since the amplification and transmission of high PAPR signals is critical, this work also proposes efficient MS transmitting architectures based on space power combining techniques. This thesis also addresses other not less important issues, namely self-jamming in passive RFID readers, which is the second limiting factor of passive-backscatter systems. A suitable self-jamming suppression scheme was first used for CW signals and then extended to MS signals, yielding a CW isolation up to 50 dB and a MS isolation up 60 dB. Finally, a battery-less remote control system was developed and integrated in a commercial TV device with the purpose of demonstrating a practical application of wireless power transfer and passive-backscatter concepts. This allowed battery-free control of four basic functionalities of the TV (CH+,CH-,VOL+,VOL-).No contexto da internet das coisas (IoT), onde são esperados bilhões de objetos conectados espalhados pelo planeta de forma ubíqua, torna-se impraticável uma frequente manutenção e troca de baterias dos dispositivos sem fios ubíquos. Nestes cenários, os sistemas radio backscatter passivos terão um papel preponderante dado o seu baixo custo, baixa complexidade e não necessidade de baterias nos nós móveis. Uma vez que a transmissão de energia sem fios é o principal aspeto limitativo nestes sistemas, a sua otimização tem sido um tema central de investigação, ganhando ainda mais ênfase no contexto IoT. Tradicionalmente, a transferência de energia sem-fios é feita através de sinais CW e a maximização da eficiência é conseguida através da otimização dos circuitos recetores. Neste trabalho explora-se uma abordagem fundamentalmente diferente, em que a otimização foca-se nas formas de onda em vez dos circuitos. Demonstra-se, teoricamente e através de simulações e medidas que, devido à sua maior capacidade em superar a barreira de potencial intrínseca dos dispositivos retificadores, os sinais multi-seno (MS) de elevado PAPR são capazes de excitar os circuitos de colheita de energia de forma mais eficiente quando comparados com o sinal CW tradicional. Usando sinais MS ótimos em circuitos retificadores, foram verificadas experimentalmente melhorias de eficiência de conversão RF-DC notáveis de até 15 dB relativamente ao sinal CW. A fim de mostrar a eficácia desta abordagem na melhoria da distância de comunicação de sistemas backscatter passivos, integrou-se um front-end MS num leitor RFID comercial e observou-se um aumento significativo de 25% na distância de leitura. Além disso, desenvolveu-se de raiz um leitor RFID baseado em software rádio, compatível com o protocolo ISO18000-6C e capaz de gerar sinais MS, com os quais interrogou-se transponders passivos, obtendo-se ganhos de sensibilidade dos transponders maiores que 3 dB. Uma vez que a amplificação de sinais de elevado PAPR é uma operação crítica, propôs-se também novas arquiteturas eficientes de transmissão baseadas na combinação de sinais em espaço livre. Esta tese aborda também outros aspetos não menos importantes, como o self-jamming em leitores RFID passivos, tido como o segundo fator limitativo neste tipo de sistemas. Estudou-se técnicas de cancelamento de self-jamming CW e estendeu-se o conceito a sinais MS, tendo-se obtido isolamentos entre o transmissor e o recetor de até 50 dB no primeiro caso e de até 60 dB no segundo. Finalmente, com o objetivo de demonstrar uma aplicação prática dos conceitos de transmissão de energia sem fios e comunicação backscatter, desenvolveu-se um sistema de controlo remoto sem pilhas, cujo protótipo foi integrado num televisor comercial a fim de controlar quatro funcionalidades básicas (CH+,CH-,VOL+,VOL-)

Analysis and Design of Silicon based Integrated Circuits for Radio Frequency Identification and Ranging Systems at 24GHz and 60GHz Frequency Bands

This scientific research work presents the analysis and design of radio frequency (RF) integrated circuits (ICs) designed for two cooperative RF identification (RFID) proof of concept systems. The first system concept is based on localizable and sensor-enabled superregenerative transponders (SRTs) interrogated using a 24GHz linear frequency modulated continuous wave (LFMCW) secondary radar. The second system concept focuses on low power components for a 60GHz continuous wave (CW) integrated single antenna frontend for interrogating close range passive backscatter transponders (PBTs). In the 24GHz localizable SRT based system, a LFMCW interrogating radar sends a RF chirp signal to interrogate SRTs based on custom superregenerative amplifier (SRA) ICs. The SRTs receive the chirp and transmit it back with phase coherent amplification. The distance to the SRTs are then estimated using the round trip time of flight method. Joint data transfer from the SRT to the interrogator is enabled by a novel SRA quench frequency shift keying (SQ-FSK) based low data rate simplex communication. The SRTs are also designed to be roll invariant using bandwidth enhanced microstrip patch antennas. Theoretical analysis is done to derive expressions as a function of system parameters including the minimum SRA gain required for attaining a defined range and equations for the maximum number of symbols that can be transmitted in data transfer mode. Analysis of the dependency of quench pulse characteristics during data transfer shows that the duty cycle has to be varied while keeping the on-time constant to reduce ranging errors. Also the worsening of ranging precision at longer distances is predicted based on the non-idealities resulting from LFMCWchirp quantization due to SRT characteristics and is corroborated by system level measurements. In order to prove the system concept and study the semiconductor technology dependent factors, variants of 24GHz SRA ICs are designed in a 130nm silicon germanium (SiGe) bipolar complementary metal oxide technology (BiCMOS) and a partially depleted silicon on insulator (SOI) technology. Among the SRA ICs designed, the SiGe-BiCMOS ICs feature a novel quench pulse shaping concept to simultaneously improve the output power and minimum detectable input power. A direct antenna drive SRA IC based on a novel stacked transistor cross-coupled oscillator topology employing this concept exhibit one of the best reported combinations of minimum detected input power level of −100 dBm and output power level of 5.6 dBm, post wirebonding. The SiGe stacked transistor with base feedback capacitance topology employed in this design is analyzed to derive parameters including the SRA loop gain for design optimization. Other theoretical contributions include the analysis of the novel integrated quench pulse shaping circuit and formulas derived for output voltage swing taking bondwire losses into account. Another SiGe design variant is the buffered antenna drive SRA IC having a measured minimum detected input power level better than −80 dBm, and an output power level greater than 3.2 dBm after wirebonding. The two inputs and outputs of this IC also enables the design of roll invariant SRTs. Laboratory based ranging experiments done to test the concepts and theoretical considerations show a maximum measured distance of 77m while transferring data at the rate of 0.5 symbols per second using SQ-FSK. For distances less than 10m, the characterized accuracy is better than 11 cm and the precision is better than 2.4 cm. The combination of the maximum range, precision and accuracy are one of the best reported among similar works in literature to the author’s knowledge. In the 60GHz close range CW interrogator based system, the RF frontend transmits a continuous wave signal through the transmit path of a quasi circulator (QC) interfaced to an antenna to interrogate a PBT. The backscatter is received using the same antenna interfaced to the QC. The received signal is then amplified and downconverted for further processing. To prove this concept, two optimized QC ICs and a downconversion mixer IC are designed in a 22nm fully depleted SOI technology. The first QC is the transmission lines based QC which consumes a power of 5.4mW, operates at a frequency range from 56GHz to 64GHz and occupies an area of 0.49mm2. The transmit path loss is 5.7 dB, receive path gain is 2 dB and the tunable transmit path to receive path isolation is between 20 dB and 32 dB. The second QC is based on lumped elements, and operates in a relatively narrow bandwidth from 59.6GHz to 61.5GHz, has a gain of 8.5 dB and provides a tunable isolation better than 20 dB between the transmit and receive paths. This QC design also occupies a small area of 0.34mm² while consuming 13.2mW power. The downconversion is realized using a novel folded switching stage down conversion mixer (FSSDM) topology optimized to achieve one of the best reported combination of maximum voltage conversion gain of 21.5 dB, a factor of 2.5 higher than reported state-of-the-art results, and low power consumption of 5.25mW. The design also employs a unique back-gate tunable intermediate frequency output stage using which a gain tuning range of 5.5 dB is attained. Theoretical analysis of the FSSDM topology is performed and equations for the RF input stage transconductance, bandwidth, voltage conversion gain and gain tuning are derived. A feasibility study for the components of the 60GHz integrated single antenna interrogator frontend is also performed using PBTs to prove the system design concept.:1 Introduction 1 1.1 Motivation and Related Work . . . . . . . . . . . . . . . . . . . . . 1 1.2 Scope and Functional Specifications . . . . . . . . . . . . . . . . . 4 1.3 Objectives and Structure . . . . . . . . . . . . . . . . . . . . . . . . 5 2 Features and Fundamentals of RFIDs and Superregenerative Amplifiers 9 2.1 RFID Transponder Technology . . . . . . . . . . . . . . . . . . . . 9 2.1.1 Chipless RFID Transponders . . . . . . . . . . . . . . . . . 10 2.1.2 Semiconductor based RFID Transponders . . . . . . . . . . 11 2.1.2.1 Passive Transponders . . . . . . . . . . . . . . . . 11 2.1.2.2 Active Transponders . . . . . . . . . . . . . . . . . 13 2.2 RFID Interrogator Architectures . . . . . . . . . . . . . . . . . . . 18 2.2.1 Interferometer based Interrogator . . . . . . . . . . . . . . . 19 2.2.2 Ultra-wideband Interrogator . . . . . . . . . . . . . . . . . . 20 2.2.3 Continuous Wave Interrogators . . . . . . . . . . . . . . . . 21 2.3 Coupling Dependent Range and Operating Frequencies . . . . . . . 25 2.4 RFID Ranging Techniques . . . . . . . . . . . . . . . . . . . . . . . 28 2.4.0.1 Received Signal Strength based Ranging . . . . . 28 2.4.0.2 Phase based Ranging . . . . . . . . . . . . . . . . 30 2.4.0.3 Time based Ranging . . . . . . . . . . . . . . . . . 30 2.5 Architecture Selection for Proof of Concept Systems . . . . . . . . 32 2.6 Superregenerative Amplifier (SRA) . . . . . . . . . . . . . . . . . . 35 2.6.1 Fundamentals . . . . . . . . . . . . . . . . . . . . . . . . . . 35 2.6.2 Modes of Operation . . . . . . . . . . . . . . . . . . . . . . 42 2.6.3 Frequency Domain Characteristics . . . . . . . . . . . . . . 45 2.7 Semiconductor Technologies for RFIC Design . . . . . . . . . . . . 48 2.7.1 Silicon Germanium BiCMOS . . . . . . . . . . . . . . . . . 48 2.7.2 Silicon-on-Insulator . . . . . . . . . . . . . . . . . . . . . . . 48 3 24GHz Superregenerative Transponder based Identification and Rang- ing System 51 3.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51 3.1.1 SRT Identification and Ranging . . . . . . . . . . . . . . . . 51 3.1.2 Power Link Analysis . . . . . . . . . . . . . . . . . . . . . . 55 3.1.3 Non-idealities . . . . . . . . . . . . . . . . . . . . . . . . . . 59 3.1.4 SRA Quench Frequency Shift Keying for data transfer . . . 61 3.1.5 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 63 3.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64 3.2.1 Low Power Direct Antenna Drive CMOS SRA IC . . . . . . 66 3.2.1.1 Circuit analysis and design . . . . . . . . . . . . . 66 3.2.1.2 Characterization . . . . . . . . . . . . . . . . . . . 69 3.2.2 Direct Antenna Drive SiGe SRA ICs . . . . . . . . . . . . . 71 3.2.2.1 Stacked Transistor Cross-coupled Quenchable Oscillator . . . . . . . . . . . . . . . . . . . . . . . . 72 3.2.2.1.1 Resonator . . . . . . . . . . . . . . . . . . 72 3.2.2.1.2 Output Network . . . . . . . . . . . . . . 75 3.2.2.1.3 Stacked Transistor Cross-coupled Pair and Loop Gain . . . . . . . . . . . . . . . . . 77 3.2.2.2 Quench Waveform Design . . . . . . . . . . . . . . 85 3.2.2.3 Characterization . . . . . . . . . . . . . . . . . . . 89 3.2.3 Antenna Diversity SiGe SRA IC with Integrated Quench Pulse Shaping . . . . . . . . . . . . . . . . . . . . . . . . . . 91 3.2.3.1 Circuit Analysis and Design . . . . . . . . . . . . 91 3.2.3.1.1 Crosscoupled Pair and Sampling Current 94 3.2.3.1.2 Common Base Input Stage . . . . . . . . 95 3.2.3.1.3 Cascode Output Stage . . . . . . . . . . . 96 3.2.3.1.4 Quench Pulse Shaping Circuit . . . . . . 96 3.2.3.1.5 Power Gain . . . . . . . . . . . . . . . . . 99 3.2.3.2 Characterization . . . . . . . . . . . . . . . . . . . 102 3.2.4 Knowledge Gained . . . . . . . . . . . . . . . . . . . . . . . 103 3.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 106 3.3.1 Superregenerative Transponders . . . . . . . . . . . . . . . 106 3.3.1.1 Bandwidth Enhanced Microstrip Patch Antennas 108 3.3.2 FMCW Radar Interrogator . . . . . . . . . . . . . . . . . . 114 3.3.3 Chirp Z-transform Based Data Analysis . . . . . . . . . . . 116 4 60GHz Single Antenna RFID Interrogator based Identification System 121 4.1 System Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121 4.2 RFIC Designs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 125 4.2.1 Quasi-circulator ICs . . . . . . . . . . . . . . . . . . . . . . 125 4.2.1.1 Transmission Lines based Quasi-Circulator IC . . 126 4.2.1.2 Lumped Elements WPD based Quasi-Circulator . 130 4.2.1.3 Characterization . . . . . . . . . . . . . . . . . . . 134 4.2.1.4 Knowledge Gained . . . . . . . . . . . . . . . . . . 135 4.2.2 Folded Switching Stage Downconversion Mixer IC . . . . . 138 4.2.2.1 FSSDM Circuit Design . . . . . . . . . . . . . . . 138 4.2.2.2 Cascode Transconductance Stage . . . . . . . . . . 138 4.2.2.3 Folded Switching Stage with LC DC Feed . . . . . 142 4.2.2.4 LO Balun . . . . . . . . . . . . . . . . . . . . . . . 145 4.2.2.5 Backgate Tunable IF Stage and Offset Correction 146 4.2.2.6 Voltage Conversion Gain . . . . . . . . . . . . . . 147 4.2.2.7 Characterization . . . . . . . . . . . . . . . . . . . 150 4.2.2.8 Knowledge Gained . . . . . . . . . . . . . . . . . . 151 4.3 Proof of Principle System Implementation . . . . . . . . . . . . . . 154 5 Experimental Tests 157 5.1 24GHz System . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 157 5.1.1 Ranging Experiments . . . . . . . . . . . . . . . . . . . . . 157 5.1.2 Roll Invariance Experiments . . . . . . . . . . . . . . . . . . 158 5.1.3 Joint Ranging and Data Transfer Experiments . . . . . . . 158 5.2 60GHz System Detection Experiments . . . . . . . . . . . . . . . . 165 6 Summary and Future Work 167 Appendices 171 A Derivation of Parameters for CB Amplifier with Base Feedback Capac- itance 173 B Definitions 177 C 24GHz Experiment Setups 179 D 60 GHz Experiment Setups 183 References 185 List of Original Publications 203 List of Abbreviations 207 List of Symbols 213 List of Figures 215 List of Tables 223 Curriculum Vitae 22

Sensores passivos alimentados por transmissão de energia sem fios para aplicações de Internet das coisas

Nowadays, the Wireless Sensor Networks (WSNs) depend on the battery duration of the sensors and there is a renewed interest in creating a passive sensor network scheme in the area of Internet of Things (IoT) and space oriented WSN systems. The challenges for the future of radio communications have a twofold evolution, one being the low power consumption and, another, the adaptability and intelligent use of the available resources. Specially designed radios should be used to reduce power consumption, and adapt to the environment in a smart and e cient way. This thesis will focus on the development of passive sensors based on low power communication (backscatter) with Wireless Power Transfer (WPT) capabilities used in IoT applications. In that sense, several high order modulations for the communication will be explored and proposed in order to increase the data rate. Moreover, the sensors need to be small and cost e ective in order to be embedded in other technologies or devices. Consequently, the RF front-end of the sensors will be designed and implemented in Monolithic Microwave Integrated Circuit (MMIC).Atualmente, as redes de sensores sem fios dependem da duração da bateria e,deste modo, existe um interesse renovado em criar um esquema de rede de sensores passivos na área de internet das coisas e sistemas de redes de sensores sem fios relacionados com o espaço. Os desafios do futuro das comunicações de rádio têm uma dupla evolução, sendo um o baixo consumo de energia e, outro, a adaptação e o uso inteligente dos recursos disponíveis. Rádios diferentes dos convencionais devem ser usados para reduzir o consumo de energia e devem adaptar-se ao ambiente de forma inteligente e eficiente, de modo a que este use a menor quantidade de energia possível para estabelecer a comunicação. Esta tese incide sobre o desenvolvimento de sensores passivos baseados em comunicação de baixo consumo energético (backscatter) com recurso a transmissão de energia sem fios de modo a que possam ser usados em diferentes aplicações inseridas na internet das coisas. Nesse sentido, várias modulações de alta ordem para a comunicação backscatter serão exploradas e propostas com o objectivo de aumentar a taxa de transmissão de dados. Além disso, os sensores precisam de ser reduzidos em tamanho e económicos de modo a serem incorporados em outras tecnologias ou dispositivos. Consequentemente, o front-end de rádio frequência dos sensores será projetado e implementado em circuito integrado de microondas monolítico.Programa Doutoral em Engenharia Eletrotécnic

Saw-Less radio receivers in CMOS

Smartphones play an essential role in our daily life. Connected to the internet, we can easily keep in touch with family and friends, even if far away, while ever more apps serve us in numerous ways. To support all of this, higher data rates are needed for ever more wireless users, leading to a very crowded radio frequency spectrum. To achieve high spectrum efficiency while reducing unwanted interference, high-quality band-pass filters are needed. Piezo-electrical Surface Acoustic Wave (SAW) filters are conventionally used for this purpose, but such filters need a dedicated design for each new band, are relatively bulky and also costly compared to integrated circuit chips. Instead, we would like to integrate the filters as part of the entire wireless transceiver with digital smartphone hardware on CMOS chips. The research described in this thesis targets this goal. It has recently been shown that N-path filters based on passive switched-RC circuits can realize high-quality band-select filters on CMOS chips, where the center frequency of the filter is widely tunable by the switching-frequency. As CMOS downscaling following Moore’s law brings us lower clock-switching power, lower switch on-resistance and more compact metal-to-metal capacitors, N-path filters look promising. This thesis targets SAW-less wireless receiver design, exploiting N-path filters. As SAW-filters are extremely linear and selective, it is very challenging to approximate this performance with CMOS N-path filters. The research in this thesis proposes and explores several techniques for extending the linearity and enhancing the selectivity of N-path switched-RC filters and mixers, and explores their application in CMOS receiver chip designs. First the state-of-the-art in N-path filters and mixer-first receivers is reviewed. The requirements on the main receiver path are examined in case SAW-filters are removed or replaced by wideband circulators. The feasibility of a SAW-less Frequency Division Duplex (FDD) radio receiver is explored, targeting extreme linearity and compression Irequirements. A bottom-plate mixing technique with switch sharing is proposed. It improves linearity by keeping both the gate-source and gate-drain voltage swing of the MOSFET-switches rather constant, while halving the switch resistance to reduce voltage swings. A new N-path switch-RC filter stage with floating capacitors and bottom-plate mixer-switches is proposed to achieve very high linearity and a second-order voltage-domain RF-bandpass filter around the LO frequency. Extra out-of-band (OOB) rejection is implemented combined with V-I conversion and zero-IF frequency down-conversion in a second cross-coupled switch-RC N-path stage. It offers a low-ohmic high-linearity current path for out-of-band interferers. A prototype chip fabricated in a 28 nm CMOS technology achieves an in-band IIP3 of +10 dBm , IIP2 of +42 dBm, out-of-band IIP3 of +44 dBm, IIP2 of +90 dBm and blocker 1-dB gain-compression point of +13 dBm for a blocker frequency offset of 80 MHz. At this offset frequency, the measured desensitization is only 0.6 dB for a 0-dBm blocker, and 3.5 dB for a 10-dBm blocker at 0.7 GHz operating frequency (i.e. 6 and 9 dB blocker noise figure). The chip consumes 38-96 mW for operating frequencies of 0.1-2 GHz and occupies an active area of 0.49 mm2. Next, targeting to cover all frequency bands up to 6 GHz and achieving a noise figure lower than 3 dB, a mixer-first receiver with enhanced selectivity and high dynamic range is proposed. Capacitive negative feedback across the baseband amplifier serves as a blocker bypassing path, while an extra capacitive positive feedback path offers further blocker rejection. This combination of feedback paths synthesizes a complex pole pair at the input of the baseband amplifier, which is up-converted to the RF port to obtain steeper RF-bandpass filter roll-off than the conventional up-converted real pole and reduced distortion. This thesis explains the circuit principle and analyzes receiver performance. A prototype chip fabricated in 45 nm Partially Depleted Silicon on Insulator (PDSOI) technology achieves high linearity (in-band IIP3 of +3 dBm, IIP2 of +56 dBm, out-of-band IIP3 = +39 dBm, IIP2 = +88 dB) combined with sub-3 dB noise figure. Desensitization due to a 0-dBm blocker is only 2.2 dB at 1.4 GHz operating frequency. IIFinally, to demonstrate the performance of the implemented blocker-tolerant receiver chip designs, a test setup with a real mobile phone is built to verify the sensitivity of the receiver chip for different practical blocking scenarios

Low-cost electromagnetic tagging : design and implementation

Thesis (Ph. D.)--Massachusetts Institute of Technology, School of Architecture and Planning, Program in Media Arts and Sciences, 2002.Includes bibliographical references (p. 220-222).Several implementations of chipless RFID (Radio Frequency Identification) tags are presented and discussed as low-cost alternatives to chip-based RFID tags and sensors. An overview of present-day near-field electromagnetic tagging is presented, including both chip-based and chipless technologies with associated costs. As a candidate for low-cost ID tags, a design theory and implementation is presented for multiply-resonant planar metal structures. This theory includes a circuit model, a phenomenological model, and a framework for predicting the resonant frequencies as a function of geometrical and material properties. A novel physical geometry, a tree-like spiral structure, is proposed as a design that increases the number of resonances per unit area in a planar structure relative to the present day state-of-the-art. In addition to identification, it is shown how several chipless tags can also be designed to function as sensors. Several examples are discussed in detail, including: 1) a family of thermal sensor tags employing magnetic materials and 2) a family of sensor tags (to sense pressure, humidity, and pH) based on planar resonator structures. The latter section of the dissertation describes the evolution of my work in developing the necessary (and low-cost) instrumentation to support these new varieties of tag technologies, ranging from a $500 frequency-agile reader to a$5 reader for toy applications.by Richard Ribon Fletcher.Ph.D

A tunable transformer-based CMOS directional coupler for UHF RFID readers

A tunable transformer-based directional coupler for UHF RFID readers is presented. Based on the current cancellation between inductively and capacitively coupled power through a non-inverting transformer and two coupling capacitors, respectively, the proposed directional coupler exhibits high isolation performance. In addition, by a tuning capacitor array and a terminal resistor array, the notch frequency of the coupler is tunable over the global UHF RFID band. The coupler is fabricated in a SMIC 0.18-mu m CMOS process and the measured isolation is better than -60-dB from 840 MHz to 960 MHz. Besides, the transmission loss and the coupling factor at the notch frequency vary from -0.86-dB to -0.7-dB and from -16.2-dB to -15.3-dB, respectively.National Natural Science Foundation of China (NSFC) [61574008]SCI(E)ARTICLE61

Conception et réalisation d'un nouveau transpondeur DSRC à faible consommation

To increase the efficiency and safety of the road traffic, new concepts and technologies have been developed in Europe since 1992 for RTTT applications (Road Traffic & Transport Telematics). These applications use the Dedicated Short Range Communications (DSRC) devices at 5.8 GHz (ISM band). In view of the reliability and success of this technology, the use of such equipment is thus extended to the EFC (Electronic Fee Collection) or e-toll and also in many other application areas such as fleet management, public transport and parking management. Due to the broad applications, these equipments are subject to various standards CEN/TC 278, CEN ENV (EN) 12253, ETSI, etc.... The DSRC system consists in a transceiver (reader) and transponders (tags). Industrial approaches are oriented to semi-passive transponder technology, which uses the same signal sent by the reader to retransmit, performing a frequency shift and encoding data to be transmitted. This design avoids the use of the local oscillators to generate the RF wave, as in active transponders, and save electrical energy of batteries. This allows the development of relatively low cost and small size transponders. Despite advances in integrated low-power circuits technology, this concept still requires a lithium battery to operate the transponder for a period of 4-6 years. However, with the expansion of these facilities, it appears that over the years the amount of lithium to destroy has become a crucial problem for the environment. Nowadays designing a completely autonomous DSRC transponder is not feasible, since the amount of energy required is still high (8 mA/3.6 V active mode). Nevertheless, reducing the transponder electrical power consumption, as a solution to at least double the battery life, could be a good start point to improve environment protection.In this thesis we propose a new DSRC transponder with an original statechart that considerably reduces the power consumption. After validation of the new low-power consumption mode, we studied the possibility to recharge the battery of the transponder by means of Wireless Energy Harvesting. The DSRC Toll Collection RF link budget was carried out in order to estimate the amount of energy available when a car with a transponder passes through a toll system. However, RF link budget at 5.8 GHz presents a low power density, since the car does not stay enough on the DSRC antenna's field to proceed to energy harvesting. Therefore we explored another ISM frequency, the 2.45 GHz. Thus the Wireless Energy Harvesting chapter aims to further the state of the art through the design and optimization of a novel RF harvesting board design. We demonstrated that an optimum RF-DC load is required in order to achieve high RF-DC conversion efficiency. Several rectifiers and rectennas were prototyped in order to validate the numerical studies. Finally, the results obtained in this thesis are in the forefront of the State-of-the-Art of Wireless Energy Harvesting for very low available power density.Afin d'augmenter l'efficacité et la sécurité du trafic routier, de nouveaux concepts et technologies ont été développés depuis 1992 en Europe pour les applications RTTT (Road Traffic & Transport Telematics). Ces applications utilisent les équipements DSRC qui supportent les transmissions à courte distance à 5.8GHz. Vues la fiabilité et le succès de cette technologie, l'utilisation de ces équipements est ensuite étendue aux ETC (Electronic Toll Collection) ou Télépéage et aussi dans une multitude d'autres domaines d'application comme la gestion des flottes, le transport public et la gestion des parkings. Le système DSRC se compose d'un émetteur/récepteur (lecteur) et des transpondeurs (badges). En toute logique, l'approche industrielle oriente les développements vers la technologie de transpondeur semi passif qui, pour réémettre un signal utilise le signal transmis par l'émetteur–récepteur, effectue une modulation de phase d'une sous porteuse fréquentielle encodant ainsi les données à transmettre. Cette conception évite l'utilisation des oscillateurs locaux, comme dans les transpondeurs actifs, pour générer l'onde Radio Fréquence (RF). Ceci permet de produire des transpondeurs relativement à faible coût et de petite taille. Cependant ce concept nécessite quand même une batterie au Lithium pour assurer le fonctionnement du transpondeur pour une durée de 4 à 6 ans et ce malgré les progrès des technologies de circuits intégrés à faible consommation. Au fur et à mesure de l'expansion de ces équipements, il s'avère qu'avec les années la quantité des batteries au lithium à détruire deviendrait un problème crucial pour l'environnement. Aujourd'hui, la conception d'un transpondeur DSRC complètement autonome n'est pas faisable, car la quantité d'énergie nécessaire s'avère encore élevée (mode actif 8 mA/3.6 V). Néanmoins, la réduction de la consommation électrique du transpondeur, permet au moins doubler la durée de vie de la batterie et pourrait être un bon point de départ pour améliorer la protection de l'environnement.Dans cette thèse, nous proposons un nouveau transpondeur DSRC avec un diagramme d'état original qui réduit considérablement la consommation énergétique. Après validation d'un nouvel état de fonctionnement en mode très faible consommation d'énergie, nous avons étudié la possibilité de recharger la batterie du transpondeur à travers de la récupération d'énergie sans fil. Le bilan de liaison énergétique DSRC a été réalisé afin d'estimer la quantité d'énergie disponible quand une voiture avec un transpondeur passe à sous un système de péage. Toutefois, le bilan énergétique à 5.8 GHz présente une faible densité d'énergie RF, puisque la voiture ne reste pas assez sur le lobe de l'antenne DSRC afin de procéder à la récupération d'énergie. Par conséquent, nous avons alors exploré une autre fréquence ISM, le 2.45 GHz dans laquelle la présence d'émetteurs est bien plus grande. Dans le chapitre de récupération d'énergie sans fil nous présentons la conception et l'optimisation d'un nouveau récupérateur d'énergie RF. Après avoir démontré qu'une charge RF-DC optimale est nécessaire afin d'atteindre une haute efficacité de conversion RF-DC. Plusieurs redresseurs et rectennas ont été conçus pour valider les études numériques. Parmi, les résultats présentés dans cette thèse les rendement de conversion obtenus sont à l'état de l'art de la récupération d'énergie sans fil pour une très faible densité de puissance disponible