Meme kanserinin tanısı ve izlenmesi için mikrodalga uyarımlı termoakustik görüntüleme

Termoakustik görüntüleme, iyonize etkisi olmayan, noktasal ve kontrast çözünürlüğü yüksek yeni bir hibrit görüntüleme modalitesi olup kanserinin erken tanısı ve izlenmesi için uygun bir tekniktir. Bu teknik bilimsel, teknolojik ve ticari potansiyeli olan henüz klinik bir araç haline gelmemiş bir güncel bir konudur. ‘’Meme Kanserinin Tanısı ve İzlenmesi İçin Mikrodalga Uyarımlı Termoakustik Görüntüleme’’ adlı bu projede mikrodalga uyarımlı termoakustik görüntüleme (MUTAG) sisteminin gelişmiş yerli alt yapısı oluşturulmuştur. MUTAG sisteminde görüntülenmek istenen ortamı aydınlatması için mikrodalga darbe üreteci-kuvvetlendirici ünitesi tamamlanmış ve karakterizasyon ölçümleri yapılmıştır. Standart mikrodalga antenin hava-su arasındaki empadans uyumsuzluğu problemi, literatürden farklı olarak tamamen su içinde çalışan mikrodalga anten tasarlanıp gerçekleştirilerek çözülmüştür. Bilgisayar kontrollü deneysel xyz-yönlü konumlandırma-tarama ünitesi tamamlanmış test edilmiştir. Alt üniteler birlikte kullanılarak, deneysel termoakustik işaret toplanmış ve böylece mikrodalga uyarımlı termoakustik görüntü elde edilmiştir. Termoakustik görüntüleme için yüksek görüntü çözünürlüğü veren, maliyeti düşük, katmanlı doku yapısı için yeni kuramsal ve sayısal çözümleme teknikleri geliştirilmiştir. Bu amaçla, termoakustik dalga denkleminin çözümünde, meme dokusu katmanlı olarak modellenmiştir. Yansımasız ideal sınır koşulları yerine daha gerçekçi olan katmanlar üzerinde süreklilik sınır koşulları kullanılmıştır. Termoakustik dalga denkleminin çok katmanlı silindirik ve düzlemsel doku yapısı için ileri ve ters analitik çözümleri elde edilmiştir. Ayrıca, çok katmanlı yapılar için sayısal olarak benzetimi yapılmıştır. Meme dokusunun kesit taramasında termoakustik sinyali alacak olan transduser geliştirmede ön empadans uyumlama ve arka yansıma sönümlendirme katmanları tasarım ve uygulama çalışmaları yürütülmüştür. Bunun sonucunda %60oransal bant genişliğine sahip 1MHz’lik bir biyomedikal transduser elemanı yapılarak, deneysel testleri tamamlanmıştır. Daha sonra laboratuvar ortamında mevcut bilgisayar kontrollü deneysel konumlandırma-kesit tarama ünitesine ek olarak memenin içine sığabileceği silindirik hazne (açısal ve dikey) kullanılarak tarama sistemi tamamlanmıştır. Kesit tarama yapabilecek çokelemanlı halka transduser dizisi ve tarama sisteminin entegre edileceği platform ulusal kaynaklarla üretilmiştir.Thermoacoustic imaging is a new hybrid imaging modality with no ionization effect, high point and contrast resolution and is a suitable technique for early detection and monitoring of cancer. This technique is an up-to-date issue that has not yet become a clinical tool with scientific, technological and commercial potential. ‘’Microwave Induced Thermoacoustic Imaging for Breast Cancer Diagnosis and Follow-up ''This project has developed a developed localinfra-structure of microwave-induced thermoacoustic imaging (MUTAG) system.The microwave pulse generator-amplifier unit was completed and characterization measurements were made to illuminate the desired environment in the MUTAG system. The problem of incompatibility of the standard microwave antenna between air and water has been solved by designing and realizing a microwave antenna completely working in water different from the literature. The computer-controlled experimental xyz-directional positioning-scanning unit has been tested for completeness. Using the sub units together, the experimental thermoacoustic signalswas collected and thus a thermoacoustic image with microwaveexcitation was obtained. New theoretical and numerical analysis techniques have been developed for low-cost,multi-layered tissuestructure, which gives high image resolution for thermoacoustic imaging. For this purpose, in the solution of the thermoacoustic wave equation, the breast tissue is modeled as multi-layered. More realistic continuity boundary conditionson layers are used instead of ideal non-reflective boundary conditions. Forward and inverse analytical solutions have been obtained of the thermoacoustic wave equationfor the multi-layered cylindrical and planar tissue structures. In addition, it is simulated numerically for multi-layer structures. The transducer, which will receive the thermoacoustic signal during the cross-section scan of the breast tissue, has been carried out to design and implement pre-empadance alignment and backingreflection damping layers. This resulted in a 1 MHz biomedical transduser with a 60% proportional bandwidth, and the experimental tests were completed. Then, in addition to the computer-controlled experimental positioning-section scanning unit available in the laboratory environment, the scanning system is completed using a cylindrical chamber (angular and vertical) in which breast can fit. The multi-componentring transducer array, which can scan cross-sections, and the platform to integrate the scanning system are manufactured with national resources.TÜBİTA

Improving The Gain-bandwidth Performance Of Distributed Amplifiers

Tez (Doktora) -- İstanbul Teknik Üniversitesi, Fen Bilimleri Enstitüsü, 2002Thesis (PhD) -- İstanbul Technical University, Institute of Science and Technology, 2002Klasik dağılmış parametreli kuvvetlendiricilerin kayıplarını azaltmaya yönelik çalışmalardan biri negatif direnç devresi kullanılarak kayıpların kompanze edilmesidir. Ançak literatürde teklif edilen devre savak çıkışlı olup CDA’nın kompakt yapısı üzerinde bir dezavantaj oluşturmaktadır. Bundan dolayı bu tezde geçit çıkışlı yeni bir negatif direnç devresi tanıtılmıştır. Üst kesim frekansının arttırılması için önerilen diğer bir yöntem alçak geçiren filtre yapılı yapay hatlar yerine bant geçiren yapılı hatlar kullanmaktır. Bu amaçla literatürde teklif edilen yapı bant genişliğini azaltmaktadır. Bu problemi aşmak için bu tezde yeni bir yapı önerilmiş ve kazanç-frekans performansının iyileştirilmesi için çözümler üretilmiştir. Ayrıca bu tezde önerilen negatif direnç devresi yüksek frekans davranışını iyileştirmek üzere kullanılmıştır. Böylece band geçiren filtre yapılı yeni bir dağılmış parametreli kuvvetlendirici devresi elde edilmiştir. Diğer taraftan CDA’ya göre çok daha yüksek kazanç verebilen CSSDA’nın kazanç frekans performansı incelenmiş ve yapay hatlarının alçak geçiren yerine bant geçiren tipte tasarlanması durumunda bant genişliğinin arttığı gösterilmiştir. Dağılmış parametreleri kuvvetlendiriciler en çok kullanılan geniş bantlı kuvvetlenidirici devrelerden olup avantajları bu tezde verilen çalışmalarla daha da artmaktadır.Many works have been made to lessen the losses of conventional distributed amplifier. Compensation of the losses by means of negative resistance circuits is one of these works. But the output of the negative resistance circuit proposed in the literature is the drain port. This case is a disadvantage on the compactness of the CDA. Therefore a new negative resistance circuit the output of which is the gate port, has been obtained and basic design features have been given in this thesis. One of the methods to increase the upper frequency limit of the CDA is to use bandpass filter structured artificial lines. The bandpasss structure proposed in the literature causes the gain-bandwidth to be lower than that of a lowpass structured DA. In this thesis a CDA with a different BP structure has been presented to remove this problem and methods have been given to improve its frequency behaviour. Also, the negative resistance circuit given in this thesis has been used to improve the high frequency performance. As a result, a new bandpass filter structured distributed amplifier circuit has been obtained. Then, the gain-frequency performance of the CSSDA which can give higher gain than the CDA, has been investigated and it is shown that the bandwidth of the CSSDA using BP structured lines in place of LP structured lines, is wider than that of the CDA. The distributed amplifiers are of the most effective circuits for wide band amplification and their advantages increase by means of the works given in this thesis.DoktoraPh

Designing a new high Q fully CMOS tunable floating active inductor based on modified tunable grounded active inductor

A new Tunable Floating Active Inductor (TFAI) based on modified Tunable Grounded Active Inductor (TGAI) is proposed. Multi regulated cascade stage is used in TGAI to boost gain of input impedance and inductor value thus the Q factor enhancement obtained. The arrangement of Multi-Regulated Cascade (MRC) stage is caused the input transistor which determines AI self-resonance frequency to be as small as possible and it is free of body effect which is crucial in sub-micron technology. Compared to traditional CMOS spiral inductors, the active inductor proposed in this paper can substantially improve its equivalent inductance and quality factor. This TFAI was designed using the AMS 0.18 um RF CMOS process, which demonstrates an adjustable quality factor of 10∼567 with a 6∼284 nH inductance. The Q factor and value of active inductor is adjusted with bias current and flexible capacitance (varactor), respectively. The self-resonance frequency for both grounded and floating AI is about 6.2 GHz. The proposed active inductor also shows wide dynamic range and higher quality factor compared to conventional floating active inductor circuits.Publisher's Versio

A low loss, low voltage and high Q active inductor with multi-regulated cascade stage for RF applications

Numerous structural planning of active inductors have been proposed as of not long ago in literature which showing tuning conceivable outcomes, low chip area and offering integration facility, they constitute promising architecture to replace passive inductors in RF circuits. The modified of a conventional active inductor based on Gyrator-C topology consisting of both transconductance stages realized by common-source configuration with multi-regulated cascade stage is presented. The Q factor and value of active inductor is adjusted with bias current and flexible capacitance, respectively. Multi regulated cascade stage is used to boost gain of input impedance and inductor value and decrease series resistance of designed inductor witch caused loss. The circuit is suitable for low voltage operation, high quality factor and low power dissipation. Simulation results are provided for 90 nm TSMC CMOS process with 1 V supply voltage. Self-resonance frequency and power consumption of active inductor is 8.9 GHz and 1.2 mW, respectively.Publisher's Versio

CMOS high-performance UWB active inductor circuit

In order to maximize efficiency of the designed gyrator-based active inductor, advanced circuit techniques are used. Loss and noise are most important features of the AIs, where they should be low enough to have high-performance device. The gyrator-C topology is used to design a new low-loss and low-noise active inductor. The gyrator-C topology is potentially high-Q and all transistors are utilized in common-source configuration to have high impedance in input-output nodes. All transistors are free of body effect. The p-type differential pair input transistors and the feed forward path are employed to decrease noise of the proposed circuit. Additionally, inductance value and quality factor are adjusted by variation bias current which gives to the device tunable capability. HSPICE simulation results are presented to verify the performance of the circuit, where the 180 nm CMOS process and 1.8 V power supply are used. The noise voltage and power dissipation are less than 2.8 nV/ √ Hz and 1.3 mW, respectively.Publisher's Versio

An accurate CMOS interface small capacitance variation sensing circuit for capacitive sensor applications

In this paper, an accurate front-end CMOS interface circuit for sensing very small capacitance changes in capacitive sensors is presented. The proposed structure scales capacitance variation to the sensible impedance changing. The scaling factor of the circuit can be easily tuned by adjusting bias points of the transistors. In order to cancel or decrease the parasitic components, the RC feedback and input transistor cascading techniques are employed in the design. To simulate the circuit, HSPICE simulator is utilized to verify the validity of the theoretical formulations in 0.18 mu m technology. According to schematic and post-layout simulation results, input impedance changes linearly versus capacitance variations up to 0.7 GHz, while the sensor capacitance changing is varied between 0 and 200 fF. According to the simulation results, total dc power consumption is obtained as low as 1 mW with 0.9 V power supply.Publisher's Versio

A new high performance CMOS active inductor

A new high-performance active inductor with ability to tune its self-resonance frequency and quality factor without affecting each other is presented in this letter. Using the input transistor of active inductor in cascoding configuration gives this property to designed circuit. Furthermore, the input transistor topology make the device robust in terms of its performance over variation in process and temperature. On the other hand, RC feedback is used to cancel the parasitic components in input node of the active device, which results to improve circuit performance. Schematic and post-layout simulation results shows the theory validity of the design. Monte Carlo and temperature analysis is done to show structure robustness in PVT variation. Inductive behavior frequency range of suggested structure is 0.3-11.4 GHz. Maximum quality factor is obtained as high as 3.7k at 6.3 GHz. Total power consumption is as low as 1mW with 1.8 V power supply.Publisher's Versio

Design of a new low loss fully CMOS tunable floating active inductor

In this paper, a new tunable floating active inductor based on a modified tunable grounded active inductor is proposed. The multi regulated cascade stage is used in the proposed active structure to decrease the parasitic series resistance of active inductor, thus the Q factor enhancement is obtained. Furthermore, the arrangement of this stage leads to the smaller input transistor which determines active inductor’s self-resonance frequency and to be free of body effect which is crucial in sub-micron technology. Symmetrical design strategy has enabled both ports of the proposed floating active inductor to demonstrate the same properties. The Q factor and active inductor value are tuned with bias current and flexible capacitance (varactor), respectively. The self-resonance frequency of floating active inductor (~6.2 GHz) is almost the same as grounded prototype. In addition, the proposed active inductor also shows higher quality factor and inductance value compared to the conventional floating active inductor circuits. To show the performance of suggested circuit, simulations are done by using a 0.18 µm CMOS process, which demonstrates an adjustable quality factor of 10–567 with an inductance value range of 6–284 nH. Total DC power consumption and occupied area are 2 mW and 934.4 µm2, respectively.Publisher's Versio

Low-loss active inductor with independently adjustable self-resonance frequency and quality factor parameters

This work presents a new low-loss active inductor whose self-resonance frequency and quality factor parameters can be adjusted independently from each other. In order to achieve this property, a new input topology has been employed which consists of cascode structure with a diode connected transistor. Furthermore, the proposed input topology makes the device robust in terms of its performance over variation in process, voltage and temperature. Additionally, RC feedback is used to cancel series-loss resistance of the active inductor, which allows self-resonant enhancement as well. Schematic and post-layout simulation results show the theoretical validity of the design. To validate the design feasibility for process, voltage and temperature changes, Monte Carlo and temperature analysis are done. Suggested structure shows inductor behavior in the frequency range of 0.3–11.3 GHz. Maximum quality factor is obtained as high as 2.1k at 5.9 GHz. Total power consumption is as low as 1 mW with 1.8 V power supply.Publisher's Versio

High Efficiency Wideband Power Amplifier with Class-J Configuration

The design and implementation of a high efficiency Class-J mode RF power amplifier (PA) for wireless communications applications is described here. In this study, a broadband class-J power amplifier with GaN HEMT transistor is designed to achieve 40 dBm output power and 10 dB gain, high efficiency and linearity performance in the 2.5-3.5 GHz frequency band. Experimental results indicate good agreement with simulations verifying and demonstrating the class-J mode operation. The obtained power added efficiency (PAE) is above 68% and the output power is 39.84 dBm at an input drive of 30 dBm. High efficiency is achieved in the frequency range from 2.5 GHz to 3.5 GHz. Simulation and experimental results show that the class-J RF power amplifier can be realized more effectively in terms of a better compromise between power and efficiency trade-offs over a significant RF bandwidth than conventional class-AB/B operations. the ACPR value for the linearity measurement was found to be around -30 dBc