12 research outputs found

    Novel substrate integrated waveguide filters and circuits

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    The main work in this thesis is to explore novel microwave filters with more compact size and improved performance by taking advantage of new substrate integrated waveguide (SIW) structures, such as the ridge substrate integrated waveguide, half mode substrate integrated waveguide (HMSIW) and SIW with complementary split ring resonators (CSRRs). This thesis therefore presents the following topics: 1. Development of a design strategy to convert from a conventional ridge waveguide configuration with solid walls to the SIW counterpart, and the design of a bandpass filter based on the ridge SIW with the proposed design method. 2. Development of a ridged HMSIW to reduce the physical size of the HMSIW by loading the HMSIW with a ridge, and application of the ridged HMSIW to the design of compact bandpass filters. 3. Development of a broadside-coupled complementary split ring resonator and a capacitively-loaded complementary single split ring resonator to reduce the size of SIW with conventional CSRRs, and application of the proposed modified structures in the design of SIW and HMSIW filters with improved compactness and performance. 4. Investigation of the application of the complementary electric-LC (CELC) resonator in SIW filters with improved stopband performance, and development of a cascaded CELC resonator to further enhance the out-of-band performance

    Theoretical and experimental study of noise behavior of microwave active filters.

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    Hil-Yee Chan, Walter.Thesis (M.Phil.)--Chinese University of Hong Kong, 2000.Includes bibliographical references (leaves 84-87).Abstracts in English and Chinese.Chapter Chapter 1 --- introduction --- p.3Chapter Chapter 2 --- Background Theory --- p.6Chapter 2.1 --- Maximally Flat Filter Response --- p.6Chapter 2.2 --- Equal-Ripple Filter Response --- p.8Chapter 2.3 --- Low-pass to Band-pass Transformation --- p.9Chapter 2.4 --- Impedance and Admittance Inverter --- p.10Chapter 2.5 --- Coupled-Resonator Filter --- p.14Chapter Chapter 3 --- Active Filter Employing Negative Resistance --- p.18Chapter 3.1 --- Lossy Coupled-Resonator Filter --- p.18Chapter 3.2 --- Common-source Capacitive Feedback Configuration --- p.21Chapter 3.3 --- Active LC-resonator --- p.23Chapter 3.4 --- Design Criteria of the Active Filter --- p.24Chapter Chapter 4 --- Intermodulation Analysis --- p.27Chapter 4.1 --- IM Distortion of the Negative Resistance Circuit --- p.27Chapter 4.2 --- Analysis of the Active Coupled-Resonator Filter --- p.30Chapter 4.3 --- IM Distortion Power of a Nth Order Active Filter --- p.32Chapter Chapter 5 --- Noise Analysis --- p.37Chapter 5.1 --- Noise Basics and Noise Figure --- p.37Chapter 5.2 --- Noisy Two-Ports --- p.41Chapter 5.3 --- Correlation Matrix Representation of Noisy Two-Ports --- p.44Chapter 5.4 --- Change of Representation --- p.46Chapter 5.5 --- Interconnection of Noisy Two-Ports --- p.47Chapter 5.6 --- Correlation Matrix of the Basic Two-Ports --- p.48Chapter 5.7 --- Extraction of the Noise Parameters of MESFET --- p.51Chapter 5.8 --- Noise Parameters of CFY30 --- p.53Chapter 5.9 --- Noise Figure of CFY30 --- p.56Chapter Chapter 6 --- Noise Analysis of Passive and Active Filter --- p.60Chapter 6.1 --- Noise Current Generated by the Negative Resistance Circuit --- p.60Chapter 6.2 --- Noise Figure of the Passive Filter --- p.63Chapter 6.3 --- Noise Figure of the Active Filter --- p.65Chapter 6.3.1 --- Noise Figure of a Second-order Active Filter --- p.65Chapter 6.3.2 --- Noise Figure of the Higher-order Active Filter --- p.68Chapter 6.4 --- Design consideration of Active Filter with Optimized Noise and Linearity Performance --- p.71Chapter Chapter 7 --- Design of 900MHz Hybrid Active Filter --- p.73Chapter 7.1 --- Schematic of Active Filter --- p.73Chapter 7.2 --- Design Variants --- p.75Chapter 7.3 --- Measurement Results --- p.75Chapter 7.3.1 --- Passive Filter --- p.75Chapter 7.3.2 --- Active Filter --- p.78Chapter Chapter 8 --- Conclusion and Future Work --- p.83Reference --- p.84Author's Publications --- p.8

    Multi-passband filters and tunable filters design based on coupled resonator circuits

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    This thesis investigates multi-passband and tunable microwave filters, it includes a new generalised design technique for multi-passband filters and a new coupling tuning structure for tunable waveguide filters. The synthesis technique is an analytical approach and offers very fast solutions to the design once the desired filter specifications are given. The technique calculates the coupling matrix and external Q-factors for a wide range of filter specifications. The centre frequency and bandwidth of each passband, and the number of passbands can all be arbitrarily chosen. To verity the calculations, multi-passband filters are realised by using inverter coupled resonator sections. Two X-band waveguide multi-passband filter examples are given to validate the theory. Besides the innovation in synthesis technique, new designs of fully tunable waveguide filters are also presented. These filters are based on the new coupling tuning structure and a separate frequency tuning structure offering tuning in both centre frequency and bandwidth of the filter. One tunable bandpass filter and one tunable notch filter is implemented in X-band waveguide circuit

    Passive Microwave Components and Antennas

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    Decoherence And Defects In Cooper-Pair Boxes

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    This dissertation describes my detailed investigation of decoherence and defects in two Al/AlOx/Al Cooper-pair box (CPB) charge qubits. Both devices were coupled to thin-film lumped-element superconducting aluminum LC resonators at a temperature of 25 mK. Device 1 was previously found to have an exceptionally long energy relaxation time of T1=205 μs and a strong correlation between the lifetime T1 and the decoupling from the microwave drive line dVg,rms/dΩR,0. I determined the dephasing properties of this CPB though a series of experiments. I measured Ramsey fringes, extracted dephasing times Tφ in the range200-500 ns, and determined a corresponding bound of Sq(f=1 Hz)≤(3×10-3)2 e2/Hz on the amplitude of the 1/f charge noise affecting the qubit. I then carried out a spin echo experiment and found echo decay times Techo in the 2.4-3.3 μs range, implying a high frequency 1/f charge noise cutoff of ωc/2π≈0.2 MHz. I followed this up by fabricating and characterizing a nearly identical Device 2. This CPB had a reasonably long relaxation time T1≈4-30 μs and again the lifetime T1 and decoupling dVg,rms/dΩR,0 were correlated. Although the lifetime of Device 2 was shorter than that of Device 1, the results suggest that the exceptional relaxation time was somewhat reproducible and that this approach may lead to further improvements in qubit coherence. During my initial characterization of Device 2, I discovered that it displayed an anomalously twinned transition spectrum. I studied this feature in detail in parallel with my decoherence experiments. I found that above the resonator resonance at ω/2π=5.472 GHz the system spectrum was twinned but below it was quadrupled. This behavior was consistent with a pair of two-level systems (TLS) coupled non-resonantly to the CPB via both charge and critical current. I developed a model that matched this scenario and successfully fit the predicted spectrum to my data. Both the coherent non-resonant interaction and joint charge and critical current CPB-TLS coupling are novel observations. From the fits I extracted microscopic parameters of the fluctuators including the well asymmetry, tunneling rate, and a minimum hopping distance of 0.2-0.45 Å. I also found a large fractional change of the Josephson energy ΔEJ,k/EJ≈30-40%, consistent with a non-uniform tunnel barrier containing a few dominant conduction channels and a defect that modulates one of them

    NASA Tech Briefs, Fall 1976

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    Topics include: NASA TU Services: Technology Utilization services that can assist you in learning about and applying NASA technology; New Product Ideas: A summary of seloc.ted Innovations of value to manufacturers for the development of new products; Electronic Components and Circuits; Electronic Systems; Physical Sciences; Materials; Life Sciences; Mechanics; Machinery; Fabrication Technology; Mathematics and Information Sciences

    Dispersion Engineered Real-Time Analog Signal Processing Components and Systems

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    Résumé Avec la demande croissante pour une plus grande efficacité d’utilisation du spectre de fréquences et l’émergence de systèmes à bande ultra large (UWB) qui en découle, l’analyse d’environnements RF en temps réel est devenue d’une importance capitale. Traditionnellement, ceci est fait en utilisant des techniques d’analyse des signaux en temps réel basées soit sur une approche digitale, soit sur une approche analogique. Les appareils digitaux sont plus attrayants aux basses fréquences à cause de leur grande flexibilité, de leur taille compacte, de leur faible coût et de leur grande fiabilité. Par contre, aux plus hautes fréquences, notamment aux fréquences micro-ondes, les appareils digitaux ont des problèmes fondamentaux tels des performances faibles, un coût élevé des convertisseurs A/D et D/A et une consommation de puissance excessive. À ces fréquences, des appareils et systèmes analogiques sont requis pour des applications d’analyse des signaux en temps réel. À cause de leur mode d’opération fondamentalement analogique, ces systèmes sont appel´es analyseurs analogiques de signaux, et l’opération qu’ils effectuent est appelée analyse analogique de signaux (ASP). Cette thèse présente les plus récentes avancées au niveau des ASP. Le concept d’ASP est introduit au chapitre 1. La contribution de cette thèse au domaine des ASP est également présentée au chapitre 1. Le cœur d’un analyseur analogique de signaux en temps réel est une structure de délai dispersive (DDS). Dans une structure dispersive, la vélocité de groupe vg est une fonction de la fréquence, ce qui cause une dépendance en fréquence du délai de groupe. Par conséquent, un signal à large bande qui se propage le long d’une telle structure est sujet à un espacement dans le temps puisque ses différentes composantes spectrales voyagent avec différentes vitesses de groupes, et sont donc réarrangées dans le temps. En exploitant ce réarrangement temporel, les différentes composantes spectrales d’un signal à large bande peuvent être directement transposées dans le domaine temporel et peuvent alors être analysées en temps réel pour diverses applications. Ce concept, qui constitue le fondement des techniques ASP, est décrit au chapitre 2. En se basant sur ces principes de dispersion, le présent travail contribue au développement de nouveaux systèmes et composantes ASP ainsi qu’au développement de nouvelles DDS.----------Abstract With the ever increasing demand on higher spectral efficiencies and the related emergence of ultra-wideband (UWB) systems, monitoring RF environments in real-time has become of paramount interest. This is traditionally done using real-time signal processing techniques based on either digital or analog approaches. Digital devices are most attractive at low frequencies due to their high flexibility, compact size, low cost, and strong reliability. However, at higher frequencies, such as millimeter-wave frequencies, digital devices suffer of fundamental issues, such as poor performance, high cost for A/D and D/A converters, and excessive power consumption. At such frequencies, analog devices and systems are required for real-time signal processing applications. Owing to their fundamentally analog mode of operation, these systems are referred to as Analog Signal Processors, and the operation as Analog Signal Processing (ASP). This dissertation presents the most recent advances in these ASP concepts which are introduced in Chapter 1 along with the contribution of this thesis in this domain. The core of an analog real-time signal processor is a dispersive delay structure (DDS). In a dispersive structure, the group velocity vg is a function of frequency, which results in a frequency-dependent group delay. Consequently, a wide-band signal traveling along such a structure experiences time spreading, since its different spectral components travel with different group velocities and are therefore temporally rearranged. By exploiting this temporal rearrangement, the various spectral components of a wideband signal can be directly mapped onto time domain and can then be processed in real-time for various applications. This concept is described in Chapter 2 which forms the background of ASP techniques. Based on these dispersion principles, this work contributes to the development of novel ASP systems and devices along with the developments of novel DDSs. Two types of DDSs are used in this work: a) Composite Right/Left-Handed (CRLH) transmission lines (TL), and b) all-pass dispersive structures. In particular, the all-pass dispersive delay networks are investigated in greater details based on C-section all-pass networks in various configurations along with novel synthesis procedures and electromagnetic analysis to synthesize arbitrary group delay responses of the DDSs

    Multichannel biomedical telemetry system using delta modulation

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    Telemetering of biomedical data from unrestrained subjects requires a system to be compact, reliable and efficient. A survey of the existing multi-channel biomedical telemetry showed that most of the systems employ analogue or uncoded (digital) techniques of encoding biomedical signals. These techniques are less reliable, employ wider bandwidth and are difficult to implement compared to the coded (digital) techniques of modulation. A theoretical study of the coded techniques of modulation for encoding biomedical signals showed-that pulse code modulation, though more efficient, calls for extensive circuitry and makes it expensive and difficult to implement. Delta modulation and delta sigma modulation were found to be simpler, easier to Implement and efficient. [Continues.
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