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In this paper, prototypes of SC-cut resonators with 5 MHz resonant frequency are presented. The resulting short-term stability of some resonators has been measured lower than 8·10−-14 in terms of Allan standard deviation. The results are compared according to the overtone behavior on different vibrating modes to find a correlation with the intrinsic noise of the resonators. The comparison of these...
The application of the proposed mathematical tools, that can be used for signal processing self-generating transducers of physical quantities, are considered. Its operating mechanism is based on frequency modulation, when the frequency deviation depends on the intensity of exposure measurement parameter. It is shown that the action for leveling additive errors in the channel the signal generator is...
Considering the imminent migration of services to the Ka- and Q-bands, a payload dedicated to propagation measurements in these bands has become available from the Alphasat satellite under the coordination of the European Space Agency. This has strongly motivated the formation of many measurement campaigns across Europe in an effort to enhance the scientific databases with new, more reliable propagation...
An overview of ASKAP phased array feed (PAF) development is presented. New analytical and experimental techniques devised for ASKAP are described. Dedicated engineering test facilities are shown to be invaluable for system verification. Experience gained from PAF manufacture is compared with forecasts, and the importance of routine engineering demonstrated.
In this paper, we aim to present a surface potential based model for GaN High Electron Mobility Transistors. The analytical model is computationally efficient and can be accurately used for DC and RF predictions. It includes various effects of velocity saturation, access region resistance, temperature, gate current and noise.
In this paper we present a magnetic gradiometer based on a single core orthogonal fluxgate in fundamental mode. Contrarily to similar gradiometers based on detached sensor heads the use of a single core strongly reduces the offset instability of the output. The offset drift is caused by temperature variations and in a single ferromagnetic core the temperature is more uniform than in two detached cores...
We report the design of a 50 μW 1.2 MHz monolithic MEMS oscillator embedded in a standard 0.35 μm CMOS with dc-bias lower than 8V. This is the first-time demonstration for a sub-100 μW single-chip CMOS-MEMS oscillator operated in MHz range. To overcome the motional impedance R m > 8 MΩ under sub-10V dc-bias (VP), an ultra-low input referred noise (< 25 fA/rtHz), high gain integrator-differentiator...
The small signal levels provided by the limited size and inertial mass of miniature, open-loop MEMS accelerometers provide a challenging problem to achieve low noise and high stability needed for navigation and other applications. The challenge is made more difficult when different applications need to operate at a wide range of different peak g-levels. This paper discusses the performance achieved...
This paper deals with evaluation and simulation of direct detection radiometer, which operates in the W-frequency band. Radiometers can be used in wide range applications in industry, military and security as well. One of the possible applications where the radiometers can be used is scanning of concealed dangerous objects. Main part of the article deals with the theoretical analysis of the basic...
During the dynamic test of high power switching devices, it can be challenging to measure both high speed and low amplitude signals accurately. This paper uses fast response on-die temperature sensing as an example to investigate the electromagnetic interference control of a typical double pulse test (DPT) setup. Three common noise sources are identified: 1) Conductive common-mode noise caused by...
Recent experimental results for the sensitivity of aperture arrays at room temperature show 40 K array noise temperatures over the frequency range from 1000 MHz to 1500 MHz. Further reduction of array noise temperature is important to comply with the SKA sensitivity requirements at affordable cost. Furthermore the frequency range should be extended to a lowest frequency of 500 MHz, in order to meet...
Phased-array feeds (PAFs) can provide multi-beam capability for reflector antennas at microwave bands. For radio astronomy applications it is critical that the effective noise temperature of the PAF system be as low as practicable to be competitive with more conventional optimised single-beam systems. We describe our efforts to reduce the noise of a Vivaldi-element array by three means. The first...
Noise parameter measurements of six candidate transistors for a Square Kilometer Array (SKA) low-noise amplifier (LNA) are presented. They provide reliable data in the frequency range where some low-noise transistors are inadequately characterized. The results of these measurements inform the design of an LNA for SKA1-Survey Band 2 with measured minimum noise temperature of 21 K.
The SKA dishes will be used with single pixel feeds (resulting in a single on-axis main beam) as well as phased array feeds that will generate multiple offset beams. The final optics will be shaped to improve the performance of the single pixel systems. This shaping may, however, be to the detriment of the offset beams of the multi-beam systems. It is important to understand the extent of this. A...
The Ge0.9Sn0.1 photoconductor was fabricated with interdigitated structures on Si using a CMOS-compatible process. Temperature-dependent responsivity and specific detectivity were measured. The peak responsivity of 2.85A/W at 77K was achieved due to enhanced photoconductive gain.
Microwave radiometry is a novel method for monitoring contamination levels on high voltage insulators. The microwave radiometer described measures energy emitted from the contamination layer and could provide a safe, reliable, contactless monitoring method that is effective under dry conditions. The design of the system has focused on optimizing accuracy, stability and sensitivity using a relatively...
The ringing oscillation in turn-off of diode may induce electromagnetic interference (EMI) noise especially in fast switching operation. This study compares static and dynamic characteristics of a Si PiN diode and three type SiC Schottky barrier diodes, which have comparable voltage and current ratings, and focuses on the influence of diode characteristics on conducted emission of the continuous current...
A low-noise cryogenic phased array feed (PAF) is in development for the Green Bank Telescope (GBT). The feed consists of electrically small elements tuned to operate near 1.4 GHz and optimized for active impedance matching to cooled front end low noise amplifiers (LNAs). A prototype cryogenic PAF with analog fiber link, down-converters and streaming data acquisition system was recently tested on the...
We present a control system for a catalytic fuel reformer that optimizes economic performance. The control strategy is based on moving horizon estimation (MHE) and model predictive control (MPC). Particular features of the control strategy is the estimation of the energy content of the outlet gas mixture without direct measurements of outlet composition, the use of a metric for coking susceptibility...
This paper presents a digital bang-bang phase-locked loop that employs automatic loop gain control and loop latency reduction techniques to enhance the jitter performance. The chip is fabricated in a 40nm CMOS process. This bang-bang phase-locked loop achieves 290fsrms integrated jitter and reference spurs <-72.89dBc. It consumes 3.8mW from a 1.1V supply while operating at 3.96GHz. This translates...
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