Precision Temperature Sensors In Cmos Technology

This book describes the analysis and design of precision temperature sensors in CMOS IC technology, focusing on so-called smart temperature sensors, which provide a digital output signal that can be readily interpreted by a computer. The text shows how temperature characteristics can be used to obtain an accurate digital temperature reading. The book ends with a detailed description of three prototypes, one of which achieves the best performance reported to date.

This book describes the theory and design of high-accuracy CMOS smart temperature sensors. The major topic of the work is the realization of a smart temperature sensor that has an accuracy that is so high that it can be applied without any form of calibration. Integrated in a low-cost CMOS technology, this yields at the publication date of this book one of the most inexpensive intelligent general purpose temperature sensors in the world. The first thermometers could only be read by the human eye. The industrial revolution and the following computerization asked for more intelligent sensors, which could easily communicate to digital computers. This led to· the development of integrated temperature sensors that combine a bipolar temperature sensor and an A-to-D converter on the same chip. The implementation in CMOS technology reduces the processing costs to a minimum while having the best-suited technology to increase the (digital) intelligence. The accuracy of conventional CMOS smart temperature sensors is degraded by the offset of the read-out electronics. Calibration of these errors is quite expensive, however, dynamic offset-cancellation techniques can reduce the offset of amplifiers by a factor 100 to 1000 and do not need trimming. Chapter two gives an elaborate description of the different kinds of dynamic offset-cancellation techniques. Also a new technique is introduced called the nested chopper technique. An implementation of a CMOS nested-chopper instrumentation amplifier shows a residual offset of less than lOOn V, which is the best result reported to date.

This book describes the design and implementation of energy-efficient smart (digital output) temperature sensors in CMOS technology. To accomplish this, a new readout topology, namely the zoom-ADC, is presented. It combines a coarse SAR-ADC with a fine Sigma-Delta (SD) ADC. The digital result obtained from the coarse ADC is used to set the reference levels of the SD-ADC, thereby zooming its full-scale range into a small region around the input signal. This technique considerably reduces the SD-ADC’s full-scale range, and notably relaxes the number of clock cycles needed for a given resolution, as well as the DC-gain and swing of the loop-filter. Both conversion time and power-efficiency can be improved, which results in a substantial improvement in energy-efficiency. Two BJT-based sensor prototypes based on 1st-order and 2nd-order zoom-ADCs are presented. They both achieve inaccuracies of less than ±0.2°C over the military temperature range (-55°C to 125°C). A prototype capable of sensing temperatures up to 200°C is also presented. As an alternative to BJTs, sensors based on dynamic threshold MOSTs (DTMOSTs) are also presented. It is shown that DTMOSTs are capable of achieving low inaccuracy (±0.4°C over the military temperature range) as well as sub-1V operation, making them well suited for use in modern CMOS processes.

This book describes the background, principles, implementations, characterization, and future trends of temperature sensors made from silicon resistors in CMOS technology, including their readout circuits. Readers will benefit from the latest research of CMOS temperature sensors, and could learn about various precision analog techniques such as phase detection, continuous-time ΔΣ ADC, zoom ADC, FIR-DAC, dynamic element matching, OTA linearization, etc.

Thermal Sensors is intended as a comprehensive and accessible reference for designers and users of thermal sensors. Many different physical quantities can be converted easily and accurately into temperature differences using thermal techniques. These temperature differences can be detected with temperature and temperature-difference sensors. In a thermal sensor the thermal converter and the temperature sensor are combined in a single accurate device. This book gives an overview and deals with the design aspects of thermal and temperature sensors, with an emphasis on sensors based on silicon technology. The temperature sensors described are based on the use of various types of sensitive elements, such as platinum resistors, thermistors and special integrated circuits. The thermal sensors described include flow, conductivity, infrared, vacuum, humidity and calorimetric sensors, and ac-dc converters, thus providing a comprehensive overview of all thermal sensors, with practical examples of each type.

Integrated temperature sensors play an important role in enhancing the performance of on-chip power and thermal management systems in today's highly-integrated system-on-chip (SoC) platforms, such as microprocessors. Accurate on-chip temperature measurement is essential to maximize the performance and reliability of these SoCs. However, due to non-uniform power consumption by different functional blocks, microprocessors have fairly large thermal gradient (and variation) across their chips. In the case of multi-core microprocessors for example, there are task-specific thermal gradients across different cores on the same die. As a result, multiple temperature sensors are needed to measure the temperature profile at all relevant coordinates of the chip. Subsequently, the results of the temperature measurements are used to take corrective measures to enhance the performance, or save the SoC from catastrophic over-heating situations which can cause permanent damage. Furthermore, in a large multi-core microprocessor, it is also imperative to continuously monitor potential hot-spots that are prone to thermal runaway. The locations of such hot spots depend on the operations and instruction the processor carries out at a given time. Due to practical limitations, it is an overkill to place a big size temperature sensor nearest to all possible hot spots. Thus, an ideal on-chip temperature sensor should have minimal area so that it can be placed non-invasively across the chip without drastically changing the chip floor plan. In addition, the power consumption of the sensors should be very low to reduce the power budget overhead of thermal monitoring system, and to minimize measurement inaccuracies due to self-heating. The objective of this research is to design an ultra-small size and ultra-low power temperature sensor such that it can be placed in the intimate proximity of all possible hot spots across the chip. The general idea is to use the leakage current of a reverse-bias p-n junction diode as an operand for temperature sensing. The tasks within this project are to examine the theoretical aspect of such sensors in both Silicon-On-Insulator (SOI), and bulk Complementary Metal-Oxide Semiconductor (CMOS) technologies, implement them in deep sub-micron technologies, and ultimately evaluate their performances, and compare them to existing solutions.

With contributions from an internationally-renowned group of experts, this book uses a multidisciplinary approach to review recent developments in the field of smart sensor systems, covering important system and design aspects. It examines topics over the whole range of sensor technology from the theory and constraints of basic elements, physics and electronics, up to the level of application-orientated issues. Developed as a complementary volume to ‘Smart Sensor Systems’ (Wiley 2008), which introduces the basics of smart sensor systems, this volume focuses on emerging sensing technologies and applications, including: State-of-the-art techniques for designing smart sensors and smart sensor systems, including measurement techniques at system level, such as dynamic error correction, calibration, self-calibration and trimming. Circuit design for sensor systems, such as the design of precision instrumentation amplifiers. Impedance sensors, and the associated measurement techniques and electronics, that measure electrical characteristics to derive physical and biomedical parameters, such as blood viscosity or growth of micro-organisms. Complete sensor systems-on-a-chip, such as CMOS optical imagers and microarrays for DNA detection, and the associated circuit and micro-fabrication techniques. Vibratory gyroscopes and the associated electronics, employing mechanical and electrical signal amplification to enable low-power angular-rate sensing. Implantable smart sensors for neural interfacing in bio-medical applications. Smart combinations of energy harvesters and energy-storage devices for autonomous wireless sensors. Smart Sensor Systems: Emerging Technologies and Applications will greatly benefit final-year undergraduate and postgraduate students in the areas of electrical, mechanical and chemical engineering, and physics. Professional engineers and researchers in the microelectronics industry, including microsystem developers, will also find this a thorough and useful volume.

Explore heterogeneous circuit integration and the packaging needed for practical applications of microsystems MEMS and system integration are important building blocks for the “More-Than-Moore” paradigm described in the International Technology Roadmap for Semiconductors. And, in 3D and Circuit Integration of MEMS, distinguished editor Dr. Masayoshi Esashi delivers a comprehensive and systematic exploration of the technologies for microsystem packaging and heterogeneous integration. The book focuses on the silicon MEMS that have been used extensively and the technologies surrounding system integration. You’ll learn about topics as varied as bulk micromachining, surface micromachining, CMOS-MEMS, wafer interconnection, wafer bonding, and sealing. Highly relevant for researchers involved in microsystem technologies, the book is also ideal for anyone working in the microsystems industry. It demonstrates the key technologies that will assist researchers and professionals deal with current and future application bottlenecks. Readers will also benefit from the inclusion of: A thorough introduction to enhanced bulk micromachining on MIS process, including pressure sensor fabrication and the extension of MIS process for various advanced MEMS devices An exploration of epitaxial poly Si surface micromachining, including process condition of epi-poly Si, and MEMS devices using epi-poly Si Practical discussions of Poly SiGe surface micromachining, including SiGe deposition and LP CVD polycrystalline SiGe A concise treatment of heterogeneously integrated aluminum nitride MEMS resonators and filters Perfect for materials scientists, electronics engineers, and electrical and mechanical engineers, 3D and Circuit Integration of MEMS will also earn a place in the libraries of semiconductor physicists seeking a one-stop reference for circuit integration and the practical application of microsystems.