38 research outputs found

    ์บ˜๋ฆฌ๋ธŒ๋ ˆ์ด์…˜์ด ํ•„์š”์—†๋Š” ์œ„์ƒ๊ณ ์ • ๋ฃจํ”„์˜ ์„ค๊ณ„

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    ํ•™์œ„๋…ผ๋ฌธ (๋ฐ•์‚ฌ)-- ์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› : ์ „๊ธฐยท์ปดํ“จํ„ฐ๊ณตํ•™๋ถ€, 2017. 2. ๊น€์žฌํ•˜.A PVT-insensitive-bandwidth PLL and a chirp frequency synthesizer PLL are proposed using a constant-relative-gain digitally-controlled oscillator (DCO), a constant-gain time-to-digital converter (TDC), and a simple digital loop filter (DLF) without an explicit calibration or additional circuit components. A digital LC-PLL that realizes a PVT-insensitive loop bandwidth (BW) by using the constant-relative-gain LC-DCO and constant-gain TDC is proposed. In other words, based on ratiometric circuit designs, the LC-DCO can make a fixed percent change to its frequency for a unit change in its digital input and the TDC can maintain a fixed range and resolution measured in reference unit intervals (UIs) across PVT variations. With such LC-DCO and TDC, the proposed PLL can realize a bandwidth which is a constant fraction of the reference frequency even with a simple proportional-integral digital loop filter without any explicit calibration loops. The prototype digital LC-PLL fabricated in a 28-nm CMOS demonstrates a frequency range of 8.38~9.34 GHz and 652-fs,rms integrated jitter from 10-kHz to 1-GHz at 8.84-GHz while dissipating 15.2-mW and occupying 0.24-mm^2. Also, the PLL across three different die samples and supply voltage ranging from 1.0 to 1.2V demonstrates a nearly constant BW at 822-kHz with the variation of ยฑ4.25-% only. A chirp frequency synthesizer PLL (FS-PLL) that is capable of precise triangular frequency modulation using type-III digital LC-PLL architecture for X-band FMCW imaging radar is proposed. By employing a phase-modulating two-point modulation (TPM), constant-gain TDC, and a simple second-order DLF with polarity-alternating frequency ramp estimator, the PLL achieves a gain self-tracking TPM realizing a frequency chirp with fast chirp slope (=chirp BW/chirp period) without increasing frequency errors around the turn-around points, degrading the effective resolution achievable. A prototype chirp FS-PLL fabricated in a 65nm CMOS demonstrates that the PLL can generate a precise triangular chirp profile centered at 8.9-GHz with 940-MHz bandwidth and 28.8-us period with only 1.9-MHz,rms frequency error including the turn-around points and 14.8-mW power dissipation. The achieved 32.63-MHz/us chirp slope is higher than that of FMCW FS-PLLs previously reported by 2.6x.CHAPTER 1 INTRODUCTION 1 1.1 MOTIVATION 1 1.2 THESIS ORGANIZATION 5 CHAPTER 2 CONVENTIONAL PHASE-LOCKED LOOP 7 2.1 CHARGE-PUMP PLL 7 2.1.1 OPERATING PRINCIPLE 7 2.1.2 LOOP DYNAMICS 9 2.2 DIGITAL PLL 10 2.2.1 OPERATING PRINCIPLE 11 2.2.2 LOOP DYNAMICS 12 CHAPTER 3 VARIATIONS ON PHASE-LOCKED LOOP 14 3.1 OSCILLATOR GAIN VARIATION 14 3.1.1 RING VOLTAGE-CONTROLLED OSCILLATOR 15 3.1.2 LC VOLTAGE-CONTROLLED OSCILLATOR 17 3.1.3 LC DIGITALLY-CONTROLLED OSCILLATOR 19 3.2 PHASE DETECTOR GAIN VARIATION 20 3.2.1 LINEAR PHASE DETECTOR 20 3.2.2 LINEAR TIME-TO-DIGITAL CONVERTER 21 CHAPTER 4 PROPOSED DCO AND TDC FOR CALIBRATION-FREE PLL 23 4.1 DIGTALLY-CONTROLLED OSCILLATOR (DCO) 25 4.1.1 OVERVIEW 24 4.1.2 CONSTANT-RELATIVE-GAIN DCO 26 4.2 TIME-TO-DIGITAL CONVERTER (TDC) 28 4.2.1 OVERVIEW 28 4.2.2 CONSTANT-GAIN TDC 30 CHAPTER 5 PVT-INSENSITIVE-BANDWIDTH PLL 35 5.1 OVERVIEW 36 5.2 PRIOR WORKS 37 5.3 PROPOSED PVT-INSENSITIVE-BANDWIDTH PLL 39 5.4 CIRCUIT IMPLEMENTATION 41 5.4.1 CAPACITOR-TUNED LC-DCO 41 5.4.2 TRANSFORMER-TUNED LC-DCO 45 5.4.3 OVERSAMPLING-BASED CONSTANT-GAIN TDC 49 5.4.4 PHASE DIGITAL-TO-ANALOG CONVERTER 52 5.4.5 DIGITAL LOOP FILTER 54 5.4.6 FREQUENCY DIVIDER 55 5.4.7 BANG-BANG PHASE-FREQUENCY DETECTOR 56 5.5 CELL-BASED DESIGN FLOW 57 5.6 MEASUREMENT RESULTS 58 CHAPTER 6 CHIRP FREQUENCY SYNTHESIZER PLL 66 6.1 OVERVIEW 67 6.2 PRIOR WORKS 71 6.3 PROPOSED CHIRP FREQUENCY SYNTHESIZER PLL 75 6.4 CIRCUIT IMPLEMENTATION 83 6.4.1 SECOND-ORDER DIGITAL LOOP FILTER 83 6.4.2 PHASE MODULATOR 84 6.4.3 CONSTANT-GAIN TDC 85 6.4.4 VRACTOR-BASED LC-DCO 87 6.4.5 OVERALL CLOCK CHAIN 90 6.5 MEASUREMENT RESULTS 91 6.6 SIGNAL-TO-NOISE RATIO OF RADAR 98 CHAPTER 7 CONCLUSION 100 BIBLIOGRAPHY 102 ์ดˆ๋ก 109Docto

    AUTONOMOUS SURFACE DETECTION AND TRACKING FOR FMCW SNOW RADAR USING FIELD PROGRAMMABLE GATE ARRAYS

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    Sea Ice in Polar Regions is typically covered with a layer of snow. The thermal insulation properties and high albedo of the snow cover insulates the sea ice beneath it, maintaining low temperatures and limiting ice melt, and thus affecting sea ice thickness and growth rates. Remote sensing of snow cover thickness plays a major role in understanding the mass balance of sea ice, inter-annual variability of snow depth, and other factors which directly impact climate change. Researchers at the Center for Remote Sensing of Ice Sheets (CReSIS) at University of Kansas have developed an ultra-wide band FMCW Snow Radar used to measure snow thickness and map internal layers of polar firn from low and high-altitude. This system has shown outstanding performance, but it has some limitations in terms of operational altitude and relies on the operator to make adjustments during surveys to capture radar echoes if the altitude changes significantly. In this thesis, an automated onboard real-time surface tracker for the snow radar is presented to detect snow surface elevation from the aircraft and track changes in the surface elevation. A common technique for an FMCW radar to have a long-range (high-altitude) capability relies on the systemโ€™s ability to delay the reference chirp signal used for de-chirping to maintain a relatively constant beat frequency. Currently, the radar uses an analog filter bank to condition the received IF signal over discrete altitude ranges and store the spectral power in each band utilizing different Nyquist zones. During airborne missions in Polar Regions with the radar, the operator has to manually switch the filter banks whenever there is a significant change in aircraft elevation. The work done in this thesis aims at eliminating the manual switching operation and providing the radar with surface detection, chirp delay, and a constant beat frequency feedback loop to enhance its long-range capability and ensure autonomous operation

    Emerging Prototyping Activities in Joint Radar-Communications

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    The previous chapters have discussed the canvas of joint radar-communications (JRC), highlighting the key approaches of radar-centric, communications-centric and dual-function radar-communications systems. Several signal processing and related aspects enabling these approaches including waveform design, resource allocation, privacy and security, and intelligent surfaces have been elaborated in detail. These topics offer comprehensive theoretical guarantees and algorithms. However, they are largely based on theoretical models. A hardware validation of these techniques would lend credence to the results while enabling their embrace by industry. To this end, this chapter presents some of the prototyping initiatives that address some salient aspects of JRC. We describe some existing prototypes to highlight the challenges in design and performance of JRC. We conclude by presenting some avenues that require prototyping support in the future.Comment: Book chapter, 54 pages, 13 figures, 10 table

    Self-Calibrated, Low-Jitter and Low-Reference-Spur Injection-Locked Clock Multipliers

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    Department of Electrical EngineeringThis dissertation focuses primarily on the design of calibrators for the injection-locked clock multiplier (ILCM). ILCMs have advantage to achieve an excellent jitter performance at low cost, in terms of area and power consumption. The wide loop bandwidth (BW) of the injection technique could reject the noise of voltage-controlled oscillator (VCO), making it thus suitable for the rejection of poor noise of a ring-VCO and a high frequency LC-VCO. However, it is difficult to use without calibrators because of its sensitiveness in process-voltage-temperature (PVT) variations. In Chapter 2, conventional frequency calibrators are introduced and discussed. This dissertation introduces two types of calibrators for low-power high-frequency LC-VCO-based ILFMs in Chapter 3 and Chapter 4 and high-performance ring-VCO-based ILCM in Chapter 5. First, Chapter 3 presents a low power and compact area LC-tank-based frequency multiplier. In the proposed architecture, the input signals have a pulsed waveform that involves many high-order harmonics. Using an LC-tank that amplifies only the target harmonic component, while suppressing others, the output signal at the target frequency can be obtained. Since the core current flows for a very short duration, due to the pulsed input signals, the average power consumption can be dramatically reduced. Effective removal of spurious tones due to the damping of the signal is achieved using a limiting amplifier. In this work, a prototype frequency tripler using the proposed architecture was designed in a 65 nm CMOS process. The power consumption was 950 ??W, and the active area was 0.08 mm2. At a 3.12 GHz frequency, the phase noise degradation with respect to the theoretical bound was less than 0.5 dB. Second, Chapter 4 presents an ultra-low-phase-noise ILFM for millimeter wave (mm-wave) fifth-generation (5G) transceivers. Using an ultra-low-power frequency-tracking loop (FTL), the proposed ILFM is able to correct the frequency drifts of the quadrature voltage-controlled oscillator of the ILFM in a real-time fashion. Since the FTL is monitoring the averages of phase deviations rather than detecting or sampling the instantaneous values, it requires only 600??W to continue to calibrate the ILFM that generates an mm-wave signal with an output frequency from 27 to 30 GHz. The proposed ILFM was fabricated in a 65-nm CMOS process. The 10-MHz phase noise of the 29.25-GHz output signal was ???129.7 dBc/Hz, and its variations across temperatures and supply voltages were less than 2 dB. The integrated phase noise from 1 kHz to 100 MHz and the rms jitter were???39.1 dBc and 86 fs, respectively. Third, Chapter 5 presents a low-jitter, low-reference-spur ring voltage-controlled oscillator (ring VCO)-based ILCM. Since the proposed triple-point frequency/phase/slope calibrator (TP-FPSC) can accurately remove the three root causes of the frequency errors of ILCMs (i.e., frequency drift, phase offset, and slope modulation), the ILCM of this work is able to achieve a low-level reference spur. In addition, the calibrating loop for the frequency drift of the TP-FPSC offers an additional suppression to the in-band phase noise of the output signal. This capability of the TP-FPSC and the naturally wide bandwidth of the injection-locking mechanism allows the ILCM to achieve a very low RMS jitter. The ILCM was fabricated in a 65-nm CMOS technology. The measured reference spur and RMS jitter were ???72 dBc and 140 fs, respectively, both of which are the best among the state-of-the-art ILCMs. The active silicon area was 0.055 mm2, and the power consumption was 11.0 mW.clos

    Optimised soft-core processor architecture for noise jamming

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    M.Ing. (Electrical & Electronic Engineering)Abstract: Noise jamming is a traditional electronic counter measure (ECM) that existed since the establishment of electronic warfare (EW). Traditional noise jamming techniques have been shown to be failing when interacting with intelligent Radar systems such as pulse Doppler radar. Hence there is a need to introduce new noise jamming techniques with digital architecture that will provide improved performance against smart pulse Doppler radar. The work is undertaken to investigate the feasibility of digitizing noise jamming. It focuses on analog-to-digital conversion optimization towards noise jamming architecture, as a result digitization will allow for an opportunity for adaptation of intelligent processing that previously didnโ€™t exist. In this dissertation, certain contributions to the field of noise jamming were made by introducing state of the art odd/even order sampling architecture by proving four case studies. Case study 1 experimentally investigates sample frequency behaviour. Case study 2 uses simulation to investigate step-size and dynamic range behaviour. Case study 3 uses FPGA implementation and SNR to investigate quantization error behaviour. Case study 3 also uses SNR to investigate superiority of proposed odd/even order sampling. Lastly case study 4 uses field measurements, FPGA implementation and SNR to investigate practical implementation of digitized noise jamming. The main contribution is concerned with an architecture that digitizes, reduces sample frequency, optimizes digital resource utilization while reducing noise jamming signal-to-noise ratio. The approach evaluates and empirically compares three sampling techniques from lecture Mod-ฮ”, Mod-ฮ” (Gaussian) and Mod-ฮ” (Sinusoidal) with proposed novel odd/even order sampling. Sampling techniques are evaluated in terms of quantization error, mean square error and signal-to-noise ratio. It was found that the proposed novel odd/even order sampling achieved most case SNR performance of 6 dB in comparison to 18 dB for Mod-ฮ”. Sampling frequency findings indicated that the proposed novel odd/even order sampling had achieved sampling frequency of 2 kHz in comparison to 8 kHz from traditional 1st order sigma-delta. Dynamic range findings indicated that the proposed odd/even order sampling achieved a dynamic range of 1.088 volts/ms in comparison to 1.185 volts/ms from traditional 1st order sigma-delta. Findings have indicated that the proposed odd/even order sampling has superior SNR and sampling frequency..

    Investigative Development of an UWB Radar for UAS-borne Applications

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    The engineering ethos of the last decade has been miniaturization. Progress in various industries like material design, semiconductor technology, and digital signal processing has resulted in low-profile electrical systems. This has facilitated the means of integration onto platforms. Sensors such as radars are typically large, heavy, and consume a lot of power. Miniaturization of radars can enable important applications like remote sensing the various aspects of the Earth System from Unmanned Aerial Systems (UAS). Information about natural topography like ice sheets, vegetation cover, and ocean currents can improve our understanding of the natural processes and continued measurements offer insight into the changes over time. Soil plays a vital role in the Earthโ€™s hydrological cycle. The moisture in soil influences the weather, vegetation, and human endeavors like construction. Models are built using an extensive set of temporal soil moisture data to predict natural disasters like droughts, floods, and landslides. It plays a central role in the areas of agriculture and water resource management and hence can influence policy making and economic decisions. In this work, an investigative approach to the design, build, and test of a 2 โ€“ 18 GHz Frequency Modulated Continuous Wave radar for snow and soil measurements is reported. The radar system is designed to be integrated to the Vapor 55 rotorcraft, which is a Group 1 UAS. The radar can operate as a scatterometer to measure backscatter signatures in all four combinations of vertical and horizontal polarizations; or as a nadir-looking sounder for fine-resolution snow thickness measurements. One of the primary contributions of this work is the exploration of a single-module that integrates the radarโ€™s RF transmitter, RF receiver, receiverโ€™s IF section, wideband sweep generator, and the DC bias circuitry for the active components. The sweep generator is based on a phase-locked loop and frequency multiplication/translation stage. The compact assembly is in the form of two multilayer Printed Circuit Boards (PCB) merged together and it occupies an area of nearly 170 cm2. This thesis describes the design, construction, and testing of the module, along with recommendations for future revisions. A commercially off-the-shelf module (Arena series by Tomorrow.io, formerly Remote Sensing Solutions) is the digital backend and it consists of an Arbitrary Waveform Generator (AWG) and a data acquisition system capable of sampling up to 250 MSPS. The module is low-profile with dimensions of 7.6 cm x 19.3 cm x 2.3 cm and weighs less than 400 g including the separate aluminum enclosure intended to be integrated with the radarโ€™s RF and mixed-signal sections. A second contribution of this work is the design of a prototype antenna front-end, which consists of four four-element antenna arrays housed in a Delrin plastic fixture and are fed using custom-designed microstrip power dividers. The dimensions of the fixture are 13.7 cm x 5.9 cm x 5.5 cm and the uniform elemental distance is 2.5 cm. The arrays are fastened to a metal sheet and a custom-designed four-layer fiberglass composite fairing protects the arrays. The entire front-end is integrated on the rotorcraft and measured in an anechoic chamber. The measured, fully integrated return loss of each array covers 2 โ€“ 18 GHz and the highest value is -7.22 dB at 5.23 GHz. The radiation pattern shows a distinct nadir-pointing main lobe for nearly the entire bandwidth, however the effects of the platform increase the average side-lobe levels to less than 10 dB for 12 โ€“ 18 GHz. The measured maximum nadir gain is 15.88 dB at 10 GHz and there is a greater than 6 dB variation in magnitude within the bandwidth. This variation is compensated by processing the backscatter data over distinct sub-bands that have a maximum nadir gain variation of 6 dB. Lastly, the thesis describes two system tests conducted to evaluate the effectiveness of a prototype radar with soil as the target. These are proof-of-concept measurements to detect differences in backscatter signatures between dry and wet soil. Gravimetric measurements of collected soil samples indicate an average change of 9.5% between the two moisture states. The antenna front-end is exclusively characterized using a Vector Network Analyzer and measurements are recorded for both co- and cross-polarization at three look angles of nadir, 15ยฐ, and 30ยฐ. The relative measurements are repeated on the same patch of land with a 1U version of the miniaturized radar. There are distinct differences in relative received power and backscatter profile for all four polarizations and at each look angle. It is observed that vertical polarization indicates a change in moisture content by an increase in the relative received power over an extended range beyond the primary backscatter signal. The horizontal polarization results in a greater peak received power for the primary backscatter signal, relative to the vertical polarization. The degradation in backscatter profile for vertical polarization is higher than horizontal polarization as a function of angle and this is observed for both dry and wet soil.The ETD Release form has been added to this record as a License bitstrea

    Photonic Time-Stretch Enabled High Throughput Microwave and MM-Wave Interferometry Applied to Fibre Grating Sensors and Non-Contact Measurement

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    The research presented in this thesis is focused towards developing real-time, high-speed applications, employing ultrafast optical microwave generation and characterisation techniques. This thesis presents a series of experiments wherein mode-locked laser pulses are utilised. Photonics-based microwave and MM-Wave generation and detection are explored and employed for applications pertaining to fibre grating sensors and non-contact measurement. The application concepts leverage techniques from optical coherence tomography and non-destructive evaluation of turbid media. In particular, I use the principle of dispersion-induced photonic Time-Stretch to slow down high-speed waveforms to speeds usable by state-of-the-art photo-detectors and digital signal processors. The concept of photonic time-stretch is applied to map instantaneous microwave frequency to the time instant of the signal, which in turn is related to spatial location as established by the space-wavelength-time conversions. The experimental methods applied throughout this thesis is based upon Michelson interferometer architecture. My original contribution to knowledge is the realisation of Photonics-based, single tone, and chirped microwave and MM-Wave pulse generation applied to deciphering physical strain profile along the length of a chirped fibre Bragg grating employed in a Michelson interferometer configuration. This interrogation scheme allows intra-grating high-resolution, high-speed, and temperature independent strain measurement. This concept is further extended to utilise photonic generation of microwave pulses to characterise surface profile information of thin film and thin plate infrared transparent slides of variable thickness setup in a Michelson interferometer architecture. The method basis for photonically generated high-frequency microwave signals utilises the principle of photonic Time-Stretch. The research was conducted in the Photonics Lab at the University of Kent. In addition, the photonically generated microwave/ MM-Wave pulses is utilised as a potential broadband frequency-swept source for non-contact measurement of turbid media. Investigation of the proof-of-concept based on an MM-Wave coherence tomography set-up is implemented at Vrije Universiteit Brussel (VUB), Department of Electronics and Informatics (ETRO)

    Enabling Technology in Optical Fiber Communications: From Device, System to Networking

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    This book explores the enabling technology in optical fiber communications. It focuses on the state-of-the-art advances from fundamental theories, devices, and subsystems to networking applications as well as future perspectives of optical fiber communications. The topics cover include integrated photonics, fiber optics, fiber and free-space optical communications, and optical networking

    Superconducting Nonlinear Kinetic Inductance Devices

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    We describe a novel class of devices based on the nonlinearity of the kinetic inductance of a superconducting thin film. By placing a current-dependent inductance in a microwave resonator, small currents can be measured through their effect on the resonatorโ€™s frequency. By using a high-resistivity material for the film and nanowires as kinetic inductors, we can achieve a large coefficient of nonlinearity to improve device sensitivity. We demonstrate a current sensitivity of 8 pA/&#8730;Hz, making this device useful for transition-edge sensor (TES) readout and other cutting-edge applications. An advantage of these devices is their natural ability to be multiplexed in the frequency domain, enabling large detector arrays for TES-based instruments. A traveling-wave version of the device, consisting of a thin-film microwave transmission line, is also sensitive to small currents as they change the phase length of the line due to their effect on its inductance. We demonstrate a current sensitivity of 5 pA/&#8730;Hz for this version of the device, making it also suitable for TES readout as well as other current-detection applications. It has the advantage of multi-gigahertz bandwidth and greater dynamic range, offering a different approach to the resonator version of the device. Finally, we also demonstrate a transmission-line resonator version of the device that combines some of the advantages of the nanowire resonator and the traveling-wave device. This version of the device has high dynamic range but can also be easily multiplexed in the frequency domain. A lumped-element resonator similar to the first device can be placed in a loop configuration to make it sensitive to magnetic fields. We demonstrate an example of such a device whose sensitivity could ultimately reach levels similar to those of state-of-the-art DC SQUIDs, making it potentially useful for many magnetometry applications given its ease of multiplexing. Finally, a similar microwave resonator is shown to exhibit parametric gain of up to 29 dB in the presence of a strong pump tone. The noise performance of this parametric amplifier approaches the quantum limit, making it useful for applications in quantum information and metrology.</p
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