Design of Analog Linear Circuits, Fractional Order Systems and Bioimpedance Measurements Techniques

我的研究方向是模拟线性电路和分数阶系统的设计，包括生物阻抗测量技术。它分为两个主要领域：A)继续设计和开发能够使用模拟电路执行数学功能的新电路。其中一些功能包括滤波、放大、乘法、振荡器和一般信号处理；B)继续发展和探索分数阶系统和生物阻抗测量方法。这两个领域通过在模拟域处理的共同线索联系在一起，一个是整数顺序，另一个是分数顺序。生物阻抗测量通常使用分数系统建模，但在模拟域进行处理。研究领域A：在信号的模拟处理中是滤波器设计，在过去的几年里，我的同事、学生和我利用两个端口网络概念，利用符号数学的力量生成新颖的单差分和全差分有源滤波器。这种方法的灵活性相对较新，以前未知的滤波器已经在硅上设计，测试和实现，并显示出工作效果。注意：这项工作并不是要用标准的构建模块取代传统的滤波器设计，但有必要制定一种电路理论方法，系统地展示可以围绕最简单的一个或两个晶体管核心构建哪种类型的单差分或全差分滤波器。其优点是低功耗、小型化和设计简单。研究领域B：在分数阶系统，建模和生物阻抗测量方法领域，我的研究着眼于以下主题领域：1)生物阻抗测量技术，2)便携式阻抗分析仪的设计和实现，3)分数阶电容器在过滤器结构和超级电容器建模中的使用，以及4)水果和食品表征的建模。在生物阻抗测量技术和分析的子领域，我们的研究旨在开发生物阻抗的新方法和测量方法。我们已经开发了使用间接测量技术的低成本监测设备，可用于监测组织，农业和食品特性的生理变化，并且我的团队已经获得了低成本生物阻抗分析仪的临时专利。在分数（超级）电容器及其建模的子领域中，我们的团队已使用该元件在商业电容器无法提供的滤波器中产生不寻常的不对称特性。最近，我们一直在研究先进的技术来模拟超级电容器，并更好地预测它们在充放电条件下的行为。

My research is in the design of analog linear circuits and fractional order systems, including bioimpedance measurement techniques. It is divided into two main areas aimed at: A) Continuing the design and development of new circuits capable of performing mathematical functions using analog circuits. Several of these functions include filtering, amplification, multiplication, oscillators, and general signal processing; B) Continuing the development and exploration of fractional order systems and bio-impedance measurement methods. The two areas are linked by the common thread of being processed in the analog domain with one being integer order and the other being fractional order. Bio-impedance measurement is often modeled using fractional systems, but is processed in the analog domain. Research area A: In the analog processing of signals is filter design which, in the last several years my colleagues, students, and I have made use of two port network concepts to generate novel single and fully differential active filters using the power of symbolic math. The flexibility of this method is relatively new and previously unknown filters have been designed, tested, and implemented in silicon and shown to work. Note: this work is not meant to replace conventional filter design using standard building blocks, but there is a need to formulate a circuit theoretic approach that systematically shows what types of single or fully differential filters that can be built around the simplest possible one or two-transistor core. The advantages to be gained are low power consumption, miniaturization, and simplicity of design. Research area B: In the area of fractional order systems, modelling, and bio-impedance measurement methods my research looks at the following subject areas: 1)Bioimpedance measurement techniques, 2)Design and implementation of portable impedance analyzers, 3)Use of fractional capacitors in filter structures and modelling of supercapacitors and, 4)Modelling of fruits and food characterization. In the subareas of bioimpedance measurement techniques and analysis, our research aims to develop new means and measurement of bioimpedance in general. Already we have developed low-cost monitoring devices using indirect measurement techniques that can be used for monitoring physiological changes in tissues, agriculture, and food characterization and a provisional patent has been granted to my group for a low cost bioimpedance analyzer. In the subarea of fractional (super)capacitors and their modelling this element has been used by our group to produce unusual asymmetric characteristics in filters not available through commercial capacitors. More recently, we have been working on advanced techniques to model supercapacitors and better predict their behavior under charging and discharging conditions.