CMOS analog-digital circuit components for low power applications

Dissertação de mestrado em Micro and NanoelectronicsThis dissertation presents a study in the area of mixed analog/digital CMOS power extraction circuits for energy harvester. The main contribution of this work is the realization of low power consumption and high efficient circuit components employable in a management circuit for piezoelectricbased energy harvester. This thesis focuses on the development of current references and operational amplifiers addressing low power demands. A brief literature review is conducted on the components necessary for the power extraction circuit, including introduction to CMOS technology design and research of known low power circuits. It is presented with multiple implementations for voltage and current references, as well for operational amplifier designs. A self-biased current reference, capable of driving the remaining harvesting circuit, is designed and verified. A novel operational amplifier is proposed by the use of a minimum current selector circuit topology. It is a three-stage amplifier with an AB class output stage, comprised by a translinear circuit. The circuit is designed, taking into consideration noise reduction. The circuit components are designed based on the 0.35mm CMOS technology. A physical layout is developed for fabrication purposes. This technology was chosen with consideration of robustness, costliness and performance. The current reference is capable of outputting a stable 12nA current, which may remain stable in a broad range of power supply voltages with a minimum voltage of 1.6V. The operational amplifier operates correctly at voltages as low as 1.5V. The amplifier power consumption is extremely low, around 8mW, with an optimal quiescent current and minimum current preservation in the output stage.A principal contribuição desta dissertação é a implementação de circuitos integrados de muito baixo consumo e alta eficiência, prontos a ser implementados num circuito de extração de energia com base num elemento piezoelétrico. Esta tese foca-se no desenvolvimento de um circuito de referência de corrente e um amplificador operacional com baixa exigência de consumo. Uma revisão da literatura é realizada, incluindo introdução à tecnologia Complementary Metal-Oxide-Semiconductor (CMOS), e implementação de conhecidos circuitos de baixo consumo. Várias implementações de referência de tensão e corrente são consideradas, e amplificadores operacionais também. Uma referência de corrente auto polarizada com extremo baixo consumo é desenvolvida e verificada. Um amplificador operacional original é proposto com uma topologia de seleção de corrente mínima. Este circuito é constituído por três estágios, com um estágio de saída de classe AB, e um circuito translinear. O circuito tem em consideração redução de ruído na sua implementação. Os circuitos são desenvolvidos com base na tecnologia 0.35mm CMOS. Uma layout foi também desenhada com o propósito de fabricação. A tecnologia foi escolhida tendo em conta o seu custo versus desempenho. A referência de corrente produz uma corrente de 12nA, permanecendo estável para tensões de alimentação de variáveis, com uma tensão mínima de 1.6V. O circuito mostra um coeficiente de temperatura satisfatório. O amplificador operacional funciona com tensão de alimentação mínima de 1.5V, com um consumo baixo de 8mW, com uma corrente mínima mantida no estágio de saída

Modeling Deterministic Chaos Using Electronic Circuits

This paper brings a note on systematic circuit synthesis methods for modeling the dynamical systems given by mathematical model. Both classical synthesis and integrator based method is demonstrated via the relatively complicated real physical systems with possible chaotic solution. A variety of the different active building blocks are utilized to make the final circuits as simple as possible while preserving easily measurable voltage-mode state variables. Brief experimental verification, i.e. oscilloscope screenshots, is presented. The observed attractors have some structural stability and good relationship to their numerically integrated counterparts

Automatic synthesis of analog layout : a survey

A review of recent research in the automatic synthesis of physical geometry for analog integrated circuits is presented. On introduction, an explanation of the difficulties involved in analog layout as opposed to digital layout is covered. Review of the literature then follows. Emphasis is placed on the exposition of general methods for addressing problems specific to analog layout, with the details of specific systems only being given when they surve to illustrate these methods well. The conclusion discusses problems remaining and offers a prediction as to how technology will evolve to solve them. It is argued that although progress has been and will continue to be made in the automation of analog IC layout, due to fundamental differences in the nature of analog IC design as opposed to digital design, it should not be expected that the level of automation of the former will reach that of the latter any time soon

A low-power-extended-linear-range magnetic levitator

Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2007.Includes bibliographical references (p. 59-60).In this thesis, I designed and built analog circuits to extend the linear range of a magnetic levitator. Analog Devices AD633 multipliers are used to implement nonlinear terms which compensate for the electromagnet and sensor nonlinearities, which were measured experimentally. Implementing the nonlinear compensation allows the system to be operating point independent. Frequency compensation was done with a lead network since the resulting linearized levitator is essentially a double integrator. Position sensing was done using an OPB732 reflective switch. Nonlinear compensation for the sensor is done with an AD532 multiplier configured as a divider.by Rayal St. Patrick Johnson.M.Eng

The development of an on-chip-metering solution

Includes bibliographical references.Energy Measurements Ltd (EML), a joint venture partnership between Siemens and Spescom, manufacture prepaid electricity utility meters for both the local and international markets. Under the brand name CASHPOWER 2000, EML produces single and polyphase prepayment utility meters. Currently, these meters currently utilise a separate module for the measuring of electrical energy. In order to reduce component costs, EML proposed the energy measurement be conducted by the onboard Microcontroller Unit (MCU), a term known as On-Chip-Metering (OCM). It is envisioned that this would quickly translate in an increase in revenue. However, a major concern regarding this has been the increase in the required processor overhead. The CASHPOWER 2000 embedded MCU would be required to conduct all the present metering functionality in addition to the energy measurement. This, together with the cost analysis and compliance with the stipulated IEC1036 regulations, constitute the key criteria in determining the projects viability. This dissertation represents the investigative and development stages of a prototype algorithm and accompanying peripheral hardware as a possible solution for OCM. As part of the preliminary research, several examples of digital power and energy-measurement techniques were investigated. A comparative analysis of these was performed to facilitate the development of a unique solution based on the research conducted. This completed, a prototype was developed and preliminary testing was conducted to determine its compliance with the stipulated regulations for a class 2 meter, as per IEC1O36 specifications