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The reflected group delay method of designing filters is demonstrated for the first time on a four pole quasi-elliptic filter requiring cross coupling. A design procedure is proposed that involves creating optimization curves from a lumped element filter and involves using these curves to design a microstrip filter. To validate the proposed design procedure, a microstrip filter with a center frequency...
Conventional tunning mechanisms for evanescent-mode cavity resonators include changing a gap size through MEMS-based structures. In this paper, for the first time, we propose a technique for adjusting the resonant frequency of these resonators by using a nano-plasma region. For this aim, a sufficiently large DC field is applied which generates a nano-plasma layer inside the gap between the loading...
Millimeter wave mobile systems equipped with adaptive antennas show tremendous potential to provide much higher data rates than traditional cellular systems while offering comparable signal quality. This article presents channel measurement results obtained using a spread spectrum sliding correlator channel sounder at 28 GHz with an ultra-wide RF first null-to-null bandwidth of 800 MHz, collected...
This paper presents the design, implementation, and experimental evaluation of a high efficiency continuous Class BJ mode power amplifier, using a compact defected ground structure (DGS) to provide the necessary output matching and harmonic termination for broadband operation. Detailed consideration has been given to the DGS microstrip line impedance and corresponding equalization network, in order...
In this paper, the first fully integrated Optically Locked Voltage Controlled Oscillator (OL-VCO) is reported. The OL-VCO is locked to an RF source through a free-space optical link at λ=850nm. In the locked mode, the OL-VCO achieves an RMS jitter of 1.6psec with 16 averaging. It also improves the phase noise by 25dB at 100Hz offset frequency. The wireless synchronization is achieved at a distance...
This paper presents a frequency-tunable slot antenna which uses liquid metal to vary the electrical length of the radiating aperture. The liquid metal is driven by continuous electrowetting (CEW), a process by which motion is induced in a liquid-metal droplet through the application of a potential gradient across an electrolytic carrier fluid. The process is both fully reversible and repeatable, and...
In this paper, the authors present an embedded, low-cost packaging technique for high power gallium nitride devices. The package is based on flip-chip bonding to achieve a reduced parasitic inductance, easing the design for wideband amplifiers. The backside of the gallium nitride devices is connected to a heat sink by a second flip-chip process to improve thermal management. When realized on a low-cost...
A novel microfluidic-based approach for realizing highly reconfigurable bandpass filters is presented. The filter topology employs open loop resonators that are capacitively loaded with metallized glass plates. By using microfluidics, the metalized glass plates can be repositioned over the resonators to control the amount of capacitive loading and provide the frequency tuning capability. For the presented...
Quadrature receivers are employed in Doppler radar vital sign sensing to overcome position sensitivity issue of single channel receivers. However, quadrature architecture adds to the complexity of the system, and any imbalance between the two channels can introduce significant error in measurements. Pulse Doppler radar single channel receiver is investigated for extracting physiological signals. A...
A magnetic tunnel junction (MTJ)-based microwave detector is proposed and investigated. When the MTJ is excited by microwave magnetic fields, the relative angle between the free layer and pinned layer alternates, giving rise to an average resistance change. By measuring the average resistance change, the MTJ can be utilized as a microwave power sensor. Due to the nature of ferromagnetic resonance,...
In this paper, a novel positive transformer feedback down-conversion mixer is proposed to boost conversion gain. An ultra-wideband RF input is achieved by feeding RF signal at the emitter of the switching pair. Switching devices are biased so as to minimize LO input power. Area is minimized by means of transformer coupling and shielded transmission line for RF routing. The proposed mixer is implemented...
This paper presents a design method for resonator-type bandpass SAW filters that results in significantly larger bandwidth than what is currently possible with traditional SAW filter synthesis approaches. Unlike traditional lattice/ladder-type SAW filters, this method employs SAW resonators of a single resonant frequency and therefore reduces the complexity of SAW filter design. The proposed coupling-matrix-based...
This paper addresses the design and measurement results of two high frequency signal sources implemented in SiGe HBT technology. The 367 GHz signal source achieves a phase noise of −110 dBc/Hz at 10 MHz offset from the carrier and provides better than −8 dBm of output power. The 154 GHz signal source achieves a phase noise of −87 dBc/Hz at 1 MHz offset from the carrier and generates +7 dBm of differential...
A new method is presented for integrating high performance wire-based inductors into thin, planar, chip-scale formats. The method is designed for compatibility with commonly-used rapid prototyping tools, and fabrication can be automated for volume production. The chip-scale inductors are designed for inductances in the 1–10 nH range, self-resonant frequencies above 5 GHz, and quality factors exceeding...
Hetero junction Bipolar Transistor (HBT) and High Electron Mobility Transistor (HEMT) arrays are commonly used for RF and microwave high speed and high power applications. Thermoreflectance imaging can be utilized to understand the transient thermal characteristics of a GaN HEMT device. A time resolution of 50 ns clearly shows the thermal location-dependent time constants for the device, which could...
RTWO represents a transmission line based technology for clock generation providing low skew, low phase noise and multiphase signal. Compared to traditional LC oscillators, one major drawback in RTWO performance is high power consumption. To minimize power consumption, a half circuit implementation of gain stage is proposed. The concept is validated by X-band RTWOs using conventional and proposed...
The increasing industrial application of fiber reinforced plastics demands developments of new techniques for non-destructive testing. The sub-terahertz frequency band has proved to be a noteworthy option for this task. Composite structures or laminates can be inspected for foreign inclusions, delaminations, debonds, etc., using sub-terahertz sensors during the manufacturing process or maintenance...
This paper presents a 20 GHz low noise amplifier (LNA) with notch filtering from 27.5 GHz to 31 GHz in a 0.25 µm SiGe:C BiCMOS technology. Notch filters are proposed to be implemented at different stages to have minor impact on the noise figure (NF), while achieving high attenuation around 30 GHz. In comparison with a reference LNA without filtering, it achieves overall filtering of more than −30...
We present a photoconductive terahertz emitter that incorporates three-dimensional metallic nanostructures inside the device active area to offer record high optical-to-terahertz power conversion efficiencies. By use of three-dimensional metallic nanostructures the majority of photocarriers are generated within nanoscale distances from the photoconductor contact electrodes and drifted to the terahertz...
This paper presents the design of a graphene-based electronically tunable microstrip attenuator operating at the frequency of 5 GHz. The use of graphene as a variable resistor is discussed, and the modeling of its electromagnetic properties at microwave frequencies is fully addressed. The design of the graphene-based attenuator is described. The structure integrates a patch of graphene, whose characteristics...
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