An Ultra-Low-Power RFID/NFC Frontend IC Using 0.18 μm CMOS Technology for Passive Tag Applications

Battery-less passive sensor tags based on RFID or NFC technology have achieved much popularity in recent times. Passive tags are widely used for various applications like inventory control or in biotelemetry. In this paper, we present a new RFID/NFC frontend IC (integrated circuit) for 13.56 MHz passive tag applications. The design of the frontend IC is compatible with the standard ISO 15693/NFC 5. The paper discusses the analog design part in details with a brief overview of the digital interface and some of the critical measured parameters. A novel approach is adopted for the demodulator design, to demodulate the 10% ASK (amplitude shift keying) signal. The demodulator circuit consists of a comparator designed with a preset offset voltage. The comparator circuit design is discussed in detail. The power consumption of the bandgap reference circuit is used as the load for the envelope detection of the ASK modulated signal. The sub-threshold operation and low-supply-voltage are used extensively in the analog design—to keep the power consumption low. The IC was fabricated using 0.18 μ m CMOS technology in a die area of 1.5 mm × 1.5 mm and an effective area of 0.7 m m 2 . The minimum supply voltage desired is 1.2 V, for which the total power consumption is 107 μ W. The analog part of the design consumes only 36 μ W, which is low in comparison to other contemporary passive tags ICs. Eventually, a passive tag is developed using the frontend IC, a microcontroller, a temperature and a pressure sensor. A smart NFC device is used to readout the sensor data from the tag employing an Android-based application software. The measurement results demonstrate the full passive operational capability. The IC is suitable for low-power and low-cost industrial or biomedical battery-less sensor applications. A figure-of-merit (FOM) is proposed in this paper which is taken as a reference for comparison with other related state-of-the-art researches

Design And Implementation Of A Low-cost, Compact And Long Range Monostatic Uhf Rfid Reader With Read Point Extension

Tez (Yüksek Lisans) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2014Thesis (M.Sc.) -- İstanbul Technical University, Institute of Science and Technology, 2014RFiD sistemlerinin çeşitli uygulama alanlarında artan popülerliği neticesinde, özelikle UHF bandında çalışacak olan RFiD okuyucu üretimine dair ihtiyaçlar gittikçe artan bir eğilim göstermektedir. Bahsedilen ihtiyaçlar göz önüne alınarak, bu tez kapsamında yeni bir okuyucu tasarımı gerçekleştirilmiştir. Tasarlanan okuyucu, endüstriyel RFiD uygulamaları için gerekli görülen birçok ilgi çekici özelliği bünyesinde barındırmaktadır. RFiD sistemleri, kısaca radyo frekanslı kimliklendirme diye tanımlanabilmektedir. Elektromanyetik dalgaları kullanarak (kablosuz iletişim), üzerlerine RFiD etiketleri iliştirilmiş olan nesne, hayvan ve insanlardan verilerin transfer edilmesini sağlarlar. Takip, gözlem, kontrol vb. amaçlı kullanılabilmektedir. Genel itibari ile barkod sistemi gibi otomatik tanımlama teknolojileri ailesinin bir üyesidir. Tez kapsamındaki ilk iki bölümde, RFiD sisteminin detaylarına ve temel standartlarına dair bilgilere yer verilmiştir. Üçüncü bölümde, donanım sistem tasarımına ait süreçler detaylı bir şekilde ele alınmış ve simülasyon ile ölçüm sonuçlarına yer verilmiştir. Tasarlanan okuyucu; okuma noktası artırılmış, düşük maliyetli, kompakt, uzun menzilli ve Gen2 uyumlu olacak şekilde UHF bandında geliştirilmiştir. Aynı zamanda, birden fazla okuyucunun aynı anda çalıştığı yoğun ortamlarda çalışabilme özelliğine sahiptir. Okuyucu, anten çıkış gücü 30-dBm olan iki adet anten çıkış portu barındırmaktadır. Ayrıca, yenilikçi bir özellik olarak, geri yansıyan RF gücünü azaltmak için anten uydurma devresi tasarlanmıştır. Bu işlem, okuyucunun çıkış empedansının antenin empedansına uydurulması ile gerçekleştirilmektedir. Bununla birlikte, okuyucu, işlem anında antenin empedansını olası çevresel faktörlere karşı kararlı bir yapıda tutabilme kabiliyetine de sahiptir. Bunların yanı sıra, bir güç algılayıcı devresi vasıtasıyla, okuyucu için var olan yasal koşulları sağlamak adına, çıkış gücünü sınırlandırma ve kontrol etme özellikleri de mevcuttur. Donanım tasarımı esnasında, yüksek frekansta PCB tasarım teknikleri, radyo frekansı ve fizik temelleri, dijital ve analog devre tasarım teknikleri gibi farklı disiplinlerden çeşitli teknik bilgiler ve kabiliyetler kullanılmıştır. Artırılmış okuma noktası özelliği, tasarlanan bir başka donanım, RF çoklayıcı devresi, vasıtası ile sağlanmaktadır. Bu ürün sayesinde, UHF RFiD okuyucunun anten çıkışları artırılarak sistem kurulum maliyeti azaltılmaktadır. Bu cihazın amacı, çoklu anten ihtiyacı olan uygulamalarda okuyucu sayısını sabit tutarak, anten çıkış sayısını artırmaktır. Bu sayede sistemin uygulanma maliyetinde avantaj sağlanmaktadır. Ürün dahilindeki anahtarlama entegrelerinin araya girme kayıplarının az olması ve entegrelerin kontrolünü sağlayan denetleyici yapısı, okuyucuların marka modelinden bağımsız tak-çalıştır sistem modeli ürüne ait katma değerli nitelikleridir. Bu tez dahilinde tasarımı gerçekleştirilen UHF RFiD okuyucu, aynı zamanda Bilim, Sanayi ve Teknoloji Bakanlığı’nın sağlamış olduğu Ar-Ge proje destekleri kapsamında desteklenmiştir. Bu proje ve tez neticesinde, imalat masraflarını düşürmek adına okuyucu tasarımı ve üretimi yerli olarak gerçekleştirilmiş ve yurt içinde milli bir cihaz geliştirilmiştir. Proje sonucunda, başlangıçta belirlenen tüm kıstaslar başarıyla sağlanmış ve birer adet RF çoklayıcı devresi ve UHF RFiD okuyucu devresi, kontrol ünitesi ve grafiksel arayüz yazılımı ile birlikte, istenen herhangi bir RFiD uygulamasında kullanılmak üzere prototip olarak üretilmiştir.RFiD systems have an increasing popularity in various kinds of applications. Necessities are rising for the manufacture of new RFiD readers in industry especially at UHF band. Based on this concept, a new UHF RFiD reader design with extended read point capability has been presented within the scope of this thesis. Designed reader has attractive features required by some industrial RFiD applications. Before the hardware design part of the study, first, the background of RFiD and its key standards have been introduced in the first two chapters. In the third chapter, the hardware design process has been covered in detail and simulation and measurement results have been presented. The designed hardware is a low-cost, compact and long-range Gen2 compliant UHF RFiD reader with extended read point capability. The reader has up to 30 dBm (1 Watt) output RF power at two selectable antenna ports. The reader has an antenna tuning circuit, a novel feature, to reduce reflected RF power from antennas. This is achieved by tuning output impedance of the reader to the impedance of antenna. The reader can also tune the antenna impedance during operation in case the environment of the antenna changes. A power detector is used to control and limit the output power to regulatory requirements. While designing the hardware, several technical skills within a wide spectrum of disciplines were used like PCB design in high frequency, radio frequency, physics of RF, digital and analog design. Extended read point capability is provided with another hardware design called RF multiplexer circuit. This product has been designed in order to increase the number of antenna output ports of UHF RFiD reader to reduce the system implementation cost in dense antenna applications. This hardware design is also a part of another Research & Development project funded by the Ministry of Science, Industry and Technology of Turkey. As a part of this project and this thesis, the UHF RFiD reader has been designed as a domestic product to lower the cost of manufacture. As a result of this project, all the objectives have been achieved and a prototype of UHF RFiD reader, which has a control unit and a graphical user interface, and an RF multiplexer have been manufactured to be used in any desired UHF RFiD application.Yüksek LisansM.Sc

The Trusted UHF Receiver for Radio Frequency Identification of Critical Infrastructure Objects

Results of designing the low-noise amplifier, quadrature demodulator, and baseband amplifier with an integrated low-pass filter for the UHF radio frequency identification receiver are presented. IP-blocks are designed for implementation in the domestic CMOS 180 nm technology process. The low-noise amplifier is implemented with integrated single pole double throw switches based on the MOSFETs which are needed for bypass mode realization at the RF input. The benefits of this approach are increased input linearity of the receiver by no less than 30 dB with an increase of a noise figure. The quadrature demodulator is realized according to a typical design based on the passive MOSFET mixer core. The programmable-gain baseband amplifier is implemented with an integrated low-pass filter based on Tow-Thomas biquad architecture. IP-blocks designed for use in an RFID reader transceiver VLSI IC with sensitivity value no more than -75 dBm and input linearity value not less than 10 dBm in a «Talk» mode. The trustiness of the receiver is provided by the full-cycle design procedure and verification under experimental investigation. The electric parameters values of the proposed receiver correspond to foreign VLSIs implemented in a CMOS process with the same technology nodes. Thus, it is important to design the domestic ISO 18000-6C reader equipment intended for critical infrastructure

HIGH LINEARITY UNIVERSAL LNA DESIGNS FOR NEXT GENERATION WIRELESS APPLICATIONS

Design of the next generation (4G) systems is one of the most active and important area of research and development in wireless communications. The 2G and 3G technologies will still co-exist with the 4G for a certain period of time. Other applications such as wireless LAN (Local Area Network) and RFID are also widely used. As a result, there emerges a trend towards integrating multiple wireless functionalities into a single mobile device. Low noise amplifier (LNA), the most critical component of the receiver front-end, determines the sensitivity and noise figure of the receiver and is indispensable for the complete system. To satisfy the need for higher performance and diversity of wireless communication systems, three LNAs with different structures and techniques are proposed in the thesis based on the 4G applications. The first LNA is designed and optimized specifically for LTE applications, which could be easily added to the existing system to support different standards. In this cascode LNA, the nonlinearity coming from the common source (CS) and common gate (CG) stages are analyzed in detail, and a novel linear structure is proposed to enhance the linearity in a relatively wide bandwidth. The LNA has a bandwidth of 900MHz with the linearity of greater than 7.5dBm at the central frequency of 1.2GHz. Testing results show that the proposed structure effectively increases and maintains linearity of the LNA in a wide bandwidth. However, a broadband LNA that covers multiple frequency ranges appears more attractive due to system simplicity and low cost. The second design, a wideband LNA, is proposed to cover multiple wireless standards, such as LTE, RFID, GSM, and CDMA. A novel input-matching network is proposed to relax the tradeoff among noise figure and bandwidth. A high gain (>10dB) in a wide frequency range (1-3GHz) and a minimum NF of 2.5dB are achieved. The LNA consumes only 7mW on a 1.2V supply. The first and second LNAs are designed mainly for the LTE standard because it is the most widely used standard in the 4G communication systems. However, WiMAX, another 4G standard, is also being widely used in many applications. The third design targets on covering both the LTE and the WiMAX. An improved noise cancelling technique with gain enhancing structure is proposed in this design and the bandwidth is enlarged to 8GHz. In this frequency range, a maximum power gain of 14.5dB and a NF of 2.6-4.3dB are achieved. The core area of this LNA is 0.46x0.67mm2 and it consumes 17mW from a 1.2V supply. The three designs in the thesis work are proposed for the multi-standard applications based on the realization of the 4G technologies. The performance tradeoff among noise, linearity, and broadband impedance matching are explored and three new techniques are proposed for the tradeoff relaxation. The measurement results indicate the techniques effectively extend the bandwidth and suppress the increase of the NF and nonlinearity at high frequencies. The three proposed structures can be easily applied to the wideband and multi-standard LNA design

Wireless colorimetric readout to enable resource-limited point-of-care

Patientennahe Diagnostik in Entwicklungsländer birgt spezielle Herausforderungen, die ihren Erfolg bisher begrenzen. Diese Arbeit widmet sich daher der Entwicklung eines in seiner Herstellung skalierbaren und vielseitig einsetzbaren funkbasierten Auslesegerätes für Laborteststreifen. Durch die Kombination einer wachsenden Auswahl an papierbasierten Teststreifendiagnostiken mit gedruckter Elektronik und unter Berücksichtigung des diagnostischen Alltags im südlichen Afrika wurde ein Gerät entwickelt, das Teststreifen zuverlässig ausliest und die Daten per Funk an eine Datenbank übertragen kann. Die Technik basiert auf RFID-Tags (radio frequency identification devices), welche auf verschiedene flexible Substrate gedruckt wurden, um die technische Umsetzbarkeit und Funktionalität zu evaluieren. Um den Preis für die geplante Anwendung niedrig zu halten, wurden unter anderem Papier und Karton als Substrate genutzt. Das Ergebnis dieser Studie sind passive RFID-Tags auf unterschiedlichen, meist günstigen Substraten, die über eine Distanz von über 75 mm betrieben und ausgelesen werden können. Basierend auf der über RFID bereitgestellten Energie und Datenübertragung wurde eine Ausleseeinheit für Standardpapierstreifentests entwickelt und integriert. Durch das Auslesen verschiedener Teststreifen wurde das Gerät evaluiert und in seiner Aussagekraft mit einer scanner-basierten Aufnahme und anschließender Bildanalyse (ImageJ), einem kommerziellen Auslesegerät sowie einer manuellen Auslesung mit Hilfe von Farbtabellen verglichen. Das Gerät kann die Streifen zuverlässig auslesen und die Daten über die RFID-Schnittstelle übertragen. Die funkbasierte Ausleseeinheit ist mit verschiedenen kommerziellen Teststreifen sowohl im biodiagnostischen (lateral flow tests) wie auch im chemischen Bereich (pH-Wert) kompatibel. Die modulare Lösung erlaubt ein breites Einsatzgebiet und führt dadurch zu reduzierten Trainingszeiten der Anwender und einer zuverlässigen Handhabung. Die vorgestellte Lösung ist äußerst kostengünstig und bedarf keiner Wartung, wodurch sie sich sehr gut für den Einsatz in abgelegenen Feldkrankenhäusern eignet. Es wurde ein skalierbarer Prototyp entwickelt, der auf konventionellen Herstellungsverfahren der Verpackungsindustrie aufbaut. Aktuell handelt es sich noch um einen bogenbasierten Prozess, der sich aber prinzipiell auch auf Rolle-zu-Rolle Maschinen übertragen lässt. Bei der Entwicklung des Geräts spielte die Möglichkeit der lokalen Herstellung in den Einsatzländern eine große Rolle. Diese hätte neben der Generierung von Arbeitsplätzen auch den Vorteil einer einfacheren Verteilung der Geräte in ländliche Regionen, in denen sie den größten Nutzen für die Diagnostik erzielen würden

A trade-off design of microstrip broadband power amplifier for UHF applications

In this paper, the design of a Broadband Power Amplifier for UHF applications is presented. The proposed BPA is based on ATF13876 Agilent active device. The biasing and matching networks both are implemented by using microstrip transmission lines. The input and output matching circuits are designed by combining two broadband matching techniques: a binomial multi-section quarter wave impedance transformer and an approximate transformation of previously designed lumped elements. The proposed BPA shows excellent performances in terms of impedance matching, power gain and unconditionally stability over the operating bandwidth ranging from 1.2 GHz to 3.3 GHz. At 2.2 GHz, the large signal simulation shows a saturated output power of 18.875 dBm with an output 1-dB compression point of 6.5 dBm of input level and a maximum PAE of 36.26%

RFID multiantenna systems for wireless communications and sensing

Many scientific, industrial and medical applications require the measurement of different physical parameters in order to collect information about the spatially distributed status of some process. Very often this information needs to be collected remotely, either due to the spatial dispersion of the measurement points or due to their inaccessibility. A wireless embedded self-powered sensor may be a convenient solution to be placed at these inaccessible locations. This thesis is devoted to study the analytical relation governing the electromagnetic coupling between a reader and a embeddable self-powered sensor, based on radio frequency identification (RFID) technology, which is capable of wirelessly retrieving the status of physical parameters at a remote and inaccessible location. The physical parameter to be sensed may be the electromagnetic (EM) field existing at that location (primary measurement) or the indirect measurement of other parameters such as the temperature, humidity, etc. (secondary measurement). Given the simplicity of the RFID solution (highly embeddable properties, scavenging capabilities, penetration and radio coverage characteristics, etc.) the measurement can be done at a single location, or it can be extended to a set of measuring locations (an array or grid of sensors). The analytical relation is based on a reciprocity formulation studying the modulation of the scattered field by the embedded sensor in relation with the incident field, and allows to define a set of quality parameters of interest for the optimum design of the sensors. Particular attention is given to the scavenging circuitry as well as to the antenna design relevant to the sensing objective. In RFID tags, the existence of an RF harvesting section is an improvement with respect to conventional scattering field probes since it removes the need of DC biasing lines or optical fibers to modulate the sensor. However, this harvesting section introduces non-linearities in the response of the sensor, which requires a proper correction to use them as EM-field probes, although the characterization of the non-linearities of the RFID tag cannot be directly done using a conventional vector network analyzer (VNA), due to the requirements of an RFID protocol excitation. Due to this, this thesis proposes an alternative measurement approach that allows to characterize the different scattering states used for the modulation, in particular its non-linear behavior. In addittion, and taking this characterization as the starting point, this thesis proposes a new measurement setup for EM-field measurements based on the use of multiple tones to enlarge the available dynamic range, which is experimentally demonstrated in the measurement of a radiation pattern, as well as in imaging applications. The RFID-based sensor response is electromagnetically sensitive to the dielectric properties of its close environment. However, the governing formulation for the response of the probe mixes together a set of different contributions, the path-loss, the antenna impedance, the loads impedance, etc. As a consequence, it is not possible to isolate each contribution from the others using the information available with a conventional RFID sensor. This thesis mathematically proposes and experimentally develops a modification of the modulation scheme to introduce a new set of multi-load scattering states that increases the information available in the response and properly isolate each term. Moreover, this thesis goes a step forward and introduces a new scattering state of the probe sensitive to temperature variations that do not depend on the environment characteristics. This new configuration enables robust environmental sensing in addition to EM-field measurements, and sensing variations of the dielectric properties of the environment

Battery-less near field communications (nfc) sensors for internet of things (iot) applications

L’ implementació de la tecnologia de comunicació de camp proper (NFC) en els telèfons intel·ligents no para de créixer degut a l’ús d’aquesta per fer pagaments, això, junt amb el fet de poder aprofitar l’energia generada pel mòbil no només per la comunicació, sinó també per transmetre energia, el baix cost dels xips NFC, i el fet de que els telèfons tinguin connectivitat amb internet, possibilita i fa molt interesant el disseny d’etiquetes sense bateria incorporant-hi sensors i poder enviar la informació al núvol, dins del creixent escenari de l’internet de les coses (IoT). La present Tesi estudia la viabilitat d’aquests sensors, analitzant la màxima distància entre lector i sensor per proveir la potència necessària, presenta tècniques per augmentar el rang d’operació, i analitza els efectes de certs materials quan aquests estan propers a les antenes. Diversos sensors han estat dissenyats i analitzats i son presentats en aquest treball. Aquests son: Una etiqueta que mesura la humitat de la terra, la temperatura i la humitat relativa de l’aire per controlar les condicions de plantes. Un sensor per detectar la humitat en bolquers, imprès en material flexible que s’adapta a la forma del bolquer. Dues aplicacions, una per estimació de pH i una altre per avaluar el grau de maduració de fruites, basats en un sensor de color. I, per últim, s’estudia la viabilitat de sensors en implants per aplicacions mèdiques, analitzant l’efecte del cos i proposant un sistema per augmentar la profunditat a la que aquests es poden llegir utilitzant un telèfon mòbil. Tots aquests sensors poden ser alimentats i llegits per qualsevol dispositiu que disposin de connexió NFC.La implementación de la tecnología de comunicaciones de campo cercano (NFC) en los teléfonos inteligentes no para de crecer debido al uso de esta para llevar a cabo pagos, esto, junto con el hecho de poder aprovechar la energía generada por el móvil no sólo para la comunicación, sino también para transmitir energía, el bajo coste de los chips NFC, i el hecho que los teléfonos tengan conectividad a internet, posibilita y hace muy interesante el diseño de etiquetas sin batería que incorporen sensores i poder enviar la información a la nube, enmarcado en el creciente escenario del internet de las cosas (IoT). La presente Tesis estudia la viabilidad de estos sensores, analizando la máxima distancia entre lector i sensor para proveer la potencia necesaria, presenta técnicas para aumentar el rango de operación, y analiza los efectos de ciertos materiales cuando estos están cerca de las antenas. Varios sensores han sido diseñados y analizados y son presentados en este trabajo. Estos son: Una etiqueta que mide la humedad de la tierra, la temperatura y la humedad relativa del aire para controlar las condiciones de plantas. Un sensor para detectar la humedad en pañales, impreso en material flexible que se adapta a la forma del pañal. Dos aplicaciones, una para estimación de pH y otra para evaluar el grado de maduración de frutas, basados en un sensor de color. Y, por último, se estudia la viabilidad de sensores en implantes para aplicaciones médicas, analizando el efecto del cuerpo y proponiendo un sistema para aumentar la profundidad a la que estos se pueden leer usando un teléfono móvil. Todos estos sensores pueden ser alimentados y leídos por cualquier dispositivo que disponga de conexión NFC.The implementation of near field communication (NFC) technology into smartphones grows rapidly due the use of this technology as a payment system. This, altogether with the fact that the energy generated by the phone can be used not only to communicate but for power transfer as well, the low-cost of the NFC chips, and the fact that the smartphones have connectivity to internet, makes possible and very interesting the design of battery-less sensing tags which information can be sent to the cloud, within the growing internet of things (IoT) scenario. This Thesis studies the feasibility of these sensors, analysing the maximum distance between reader and sensor to provide the necessary power, presents techniques to increase the range of operation, and analyses the effects of certain materials when they are near to the antennas. Several sensors have been designed and analysed and are presented in this work. These are: a tag that measures the soil moisture, the temperature and the relative humidity of the air to control the conditions of plants. A moisture sensor for diapers, printed on flexible material that adapts to the diaper shape. Two applications, one for pH estimation and another for assessing the degree of fruit ripening, based on a colour sensor. And finally, the feasibility of sensors in implants for medical applications is studied, analysing the effect of the body and proposing a system to increase the depth at which they can be read using a mobile phone. All of these sensors can be powered and read by any NFC enabled device