Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
Results
Showing 1 to 20 of 28 for “"Varactors."”.
-
Modelling and applications of MOS varactors for high-speed CMOS clock and data recovery
The high-speed clock and data recovery (CDR) circuit is a key building block of modern communication systems with applications spanning a wide range from wireline long-haul networks to chip-to-chip and backplane communications. In this dissertation, our focus is on the modelling, design and …
-
Tunable microwave filters using ferroelectric thin films
… microwave filters incorporating BST thin film varactors operating in a frequency range between 1 GHz and 25 GHz are designed, tested and analysed. A lumped element lowpass filter incorporating integrated meander line inductors and BST parallel plate capacitors is implemented on a high …
-
High-efficiency Waveguide Tunable Leaky-wave Antennas and Phase-shifters
… In the designed antenna, the power loss in the varactors on the tunable impedance walls is the least compared to the other loss mechanisms. This is because of locating the varactors where the electric field strength is reduced in the reconfigurable waveguide. Using the designed impedance …
-
EFFECTS OF GATE THICKNESS, GATE MORPHOLOGY, AND EMISSIVE MATERIAL ON ORGANIC LIGHT EMITTING VARACTOR CAPACITOR PERFORMANCE
… must be invented. Organic light emitting varactors (OLEVs) represent a promising future in this regard and are explored here. OLEVs are built similarly to OLEDs, with an added gate. Under AC driving, this gate allows control of current flow to yield a higher maximum efficiency than the …
-
Millimeter-Wave and Sub-Terahertz Parametric Harmonic Generation
… of symmetric antiparallel pair of series varactors to achieve about 24-dB conversion loss (CL), −8-dBm maximum output power (POUT), and 18% relative bandwidth (BW). Two reconfigurable frequency multipliers (RFMs) are designed based on antiparallel nMOS-varactor pairs (APNVP) and …
-
A Fully Monolithic 2.5 GHz LC Voltage Controlled Oscillator in 0.35 μm CMOS Technology
… varactor nonlinearity on VCO performance. I-MOS varactors are shown to have substantially improved tuning range (and tuning curve linearity) over conventional MOS varactors. Practical issues pertaining to CMOS VCO circuit design, layout, and testing are also discussed. The characterization of the …
-
Modeling of In(0.49)Ga(0.51)P/GaAs Heterojunction Bipolar Transistors for ADC and MMIC Circuit Design
… is described in detail. Several monolithic varactors are empirically assessed for their contribution to the phase noise. Preliminary results for coplanar resonator structures are presented. These are presented as a means to enhance the frequency stability of the circuit. Design architectures …
-
Controlling coupling in an electrically steerable parasitic array
… nulls by using variable passive elements like varactors, avoiding the cost and complexity of devices like phase shifters. Past attempts to design multi-band ESPARs have often superimposed multiple antenna arrays, each scaled for a different frequency band. This often results in large, …
-
A circular electrostatic zipping actuator for the application of a MEMS tunable capacitor
… such as MEMS switches, tunable capacitors (varactors) or resonators in general have lower loss and consume less power than their CMOS counterparts and have seen an increase of applications in high-value communication systems as well as low-cost commercial communication networks. Significant …
-
Ambient ZeroScatter: Ambient BPSK and QPSK Backscatter Communication using Existing Digital I/O Pins
… components such as RF FETs, PIN diodes, or varactors to perform the backscatter modulation function. We demonstrate that completely unmodied digital I/O pins on MCUs and FPGAs can be re-purposed as binary phase-shift keying (BPSK) backscatter modulators in the UHF and microwave bands with …
-
Microstructure, Tunable and Pyroelectric Properties of Laser-Ablated Ba (Zr0.25 Ti0.75) O3 Thin Films
Micro-devices such as tunable varactors and infrared sensors have been of great interest in many applications such as wireless communication and thermal imaging. Thin film capacitors made of ferroelectric materials have been widely studied for use as active elements in those devices due to their …
-
Wideband reconfigurable antennas
… are presented with PIN diode switches, varactors, fixed capacitor or hard wire switches. Measured and simulated results with a very good agreement are presented, thus verifying the proposed concepts.
-
An investigation of solid state high level upconverters using hybrid computing techniques
… are not normally associated with upconverter varactors. A simple design method is also presented which may be employed for either high efficiency or high power handling.
-
Antennas using left handed transmission lines
… By loading the loop with active components, varactors, a tunable left handed loop antenna with a switchable radiation pattern is implemented. The loop gives an omnidirectional pattern with a null to z axis while working in an n = 0 mode and can switch to a pattern with a null at phi = 45° in …
-
Microwave Overlay Capacitor Fabrication on Printed Circuit Boards
A technique for making varactors in the form of parallel plate overlay capacitors, using barium strontium titanate (BST): a ferroelectric, polymer composite thick film, has been developed in this work. BST was selected due to the commercial availability of powder. This involves the use of standard …
-
A Novel Variable Inductor-Based VCO Design with 17% Frequency Tuning Range for IEEE 802.11AD Applications
… The VID in the VCO tank eliminates the base node varactors and their fixed parasitic capacitance that degrades TR in conventional VCO designs, while the differential Colpitts configuration provides advantageous performance at mm-wave frequencies and high output power for real-world applications. …
-
Sputtered (Bax, Sr1-x)TiO3, BST, Thin Films on Flexible Copper Foils for Use as a Non-Linear Dielectric
… tunable Metal-Insulator-Metal (MIM) capacitors. Varactors can be used to change the resonance frequency of a circuit allowing high speed frequency switching intra- and inter-band. 2-D geometric arrays of circuitry, where resonant frequency is independently controlled by tunable elements in each …
-
Integrated Tunable LC Higher-Order Microwave Filters for Interference Mitigation
… scheme is proposed for large tuning ratio varactors to reduce the nonlinear contribution from the varactor substantially which improves the tunable LC BPF filter linearity. Second, parallel addition and subtraction techniques were proposed to realize tunable dual-band filters. The …
-
Piezoelectric, Dielectric and Ferroelectric Thin Films on Metal Substrates for Microelectronic Applications
… circuit board applications for capacitors, varactors, and sensors; multilayer PZT piezoelectric stacks; and multilayer lead magnesium niobate-lead titanate-based dielectric and electrostrictive devices. In the case of ferroelectric PZT films on Cu foil, the capacitors do not fatigue upon …
Page 1 of 2