Using Square Wave Input for Wireless Power Transfer

A wireless power transfer (WPT) circuit is composed of a transmitting circuit with an AC power supply and a receiving circuit with a load, and the circuits are wirelessly connected each other. Then a designer chooses the wave form of the AC power supply. Many papers about WPT adopt a sinusoidal wave as the input. The frequency of the sinusoidal wave is generally determined to the resonant frequency of the circuit for high power transfer. Since the number of circuit elements in the power supply to generate a square wave is much less than that of a sinusoidal wave, WPT with a square wave input should be treated. In fact, some papers about WPT adopt a square wave as the input, and adjust the frequency of the square wave to the resonant frequency of the circuit. In this paper, we examine how the frequency of a square wave input affects power and efficiency of WPT circuits, and propose a procedure how to determine the frequency of the input to improve power and efficiency. Finally we discuss which wave should be adopted as an input and how the frequency of the input should be determined, regardless of whether resonant phenomena occur or not

Digitally-Enhanced Software-Defined Radio Receiver Robust to Out-of-Band Interference

A software-defined radio (SDR) receiver with improved robustness to out-of-band interference (OBI) is presented. Two main challenges are identified for an OBI-robust SDR receiver: out-of-band nonlinearity and harmonic mixing. Voltage gain at RF is avoided, and instead realized at baseband in combination with low-pass filtering to mitigate blockers and improve out-of-band IIP3. Two alternative “iterative” harmonic-rejection (HR) techniques are presented to achieve high HR robust to mismatch: a) an analog two-stage polyphase HR concept, which enhances the HR to more than 60 dB; b) a digital adaptive interference cancelling (AIC) technique, which can suppress one dominating harmonic by at least 80 dB. An accurate multiphase clock generator is presented for a mismatch-robust HR. A proof-of-concept receiver is implemented in 65 nm CMOS. Measurements show 34 dB gain, 4 dB NF, and 3.5 dBm in-band IIP3 while the out-of-band IIP3 is + 16 dBm without fine tuning. The measured RF bandwidth is up to 6 GHz and the 8-phase LO works up to 0.9 GHz (master clock up to 7.2 GHz). At 0.8 GHz LO, the analog two-stage polyphase HR achieves a second to sixth order HR > dB over 40 chips, while the digital AIC technique achieves HR > 80 dB for the dominating harmonic. The total power consumption is 50 mA from a 1.2 V supply

On The Non-linear Distortion Effects in an OFDM-RoF Link

Radio over Fiber (RoF) system is a promising technique for microcell and picocell applications for deployment of future ubiquitous wireless data networks. However, the performance of RoF systems can be severely degraded due to non-linear effects in the channel. Also, Orthogonal Frequency Division Multiplexing (OFDM), as a standard for broadband wireless networks, is being proposed for deployment with RoF systems to facilitate the total performance of a system. In this research, at first, the performance of OFDM-based RoF link with Mach-Zehnder modulator distortion effects has been analyzed at 5.8 GHz. Evaluation of mean-squared error of the proposed OFDM-RoF system was carried out to compare with the conventional single carrier system based RoF link after the modulator distortion case and also for fixed Signal to Noise Ratio (SNR) of 20 dB using undistorted OFDM signal. Later, nominal and offset biasing pre-distortion techniques are applied in proposed system to linearize the OFDM-RoF link. Thus, finally a comparison between the aforementioned pre-distortion techniques applied showed important observation in terms of distortion-free dynamic range and SNR to choose offset pre-distortion technique for our proposed system

An Artificial Neural Networks based Temperature Prediction Framework for Network-on-Chip based Multicore Platform

Continuous improvement in silicon process technologies has made possible the integration of hundreds of cores on a single chip. However, power and heat have become dominant constraints in designing these massive multicore chips causing issues with reliability, timing variations and reduced lifetime of the chips. Dynamic Thermal Management (DTM) is a solution to avoid high temperatures on the die. Typical DTM schemes only address core level thermal issues. However, the Network-on-chip (NoC) paradigm, which has emerged as an enabling methodology for integrating hundreds to thousands of cores on the same die can contribute significantly to the thermal issues. Moreover, the typical DTM is triggered reactively based on temperature measurements from on-chip thermal sensor requiring long reaction times whereas predictive DTM method estimates future temperature in advance, eliminating the chance of temperature overshoot. Artificial Neural Networks (ANNs) have been used in various domains for modeling and prediction with high accuracy due to its ability to learn and adapt. This thesis concentrates on designing an ANN prediction engine to predict the thermal profile of the cores and Network-on-Chip elements of the chip. This thermal profile of the chip is then used by the predictive DTM that combines both core level and network level DTM techniques. On-chip wireless interconnect which is recently envisioned to enable energy-efficient data exchange between cores in a multicore environment, will be used to provide a broadcast-capable medium to efficiently distribute thermal control messages to trigger and manage the DTM schemes

Novel ring resonator-based integrated photonic beamformer for broadband phased array receive antennas - part I: design and performance analysis

A novel optical beamformer concept is introduced that can be used for seamless control of the reception angle in broadband wireless receivers employing a large phased array antenna (PAA). The core of this beamformer is an optical beamforming network (OBFN), using ring resonator-based broadband delays, and coherent optical combining. The electro-optical conversion is performed by means of single-sideband suppressed carrier modulation, employing a common laser, Mach-Zehnder modulators, and a common optical sideband filter after the OBFN. The unmodulated laser signal is then re-injected in order to perform balanced coherent optical detection, for the opto-electrical conversion. This scheme minimizes the requirements on the complexity of the OBFN, and has potential for compact realization by means of full integration on chip. The impact of the optical beamformer concept on the performance of the full receiver system is analyzed, by modeling the combination of the PAA and the beamformer as an equivalent two-port RF system. The results are illustrated by a numerical example of a PAA receiver for satellite TV reception, showing that—when properly designed—the beamformer hardly affects the sensitivity of the receiver

Damage identification in structural health monitoring: a brief review from its implementation to the Use of data-driven applications

The damage identification process provides relevant information about the current state of a structure under inspection, and it can be approached from two different points of view. The first approach uses data-driven algorithms, which are usually associated with the collection of data using sensors. Data are subsequently processed and analyzed. The second approach uses models to analyze information about the structure. In the latter case, the overall performance of the approach is associated with the accuracy of the model and the information that is used to define it. Although both approaches are widely used, data-driven algorithms are preferred in most cases because they afford the ability to analyze data acquired from sensors and to provide a real-time solution for decision making; however, these approaches involve high-performance processors due to the high computational cost. As a contribution to the researchers working with data-driven algorithms and applications, this work presents a brief review of data-driven algorithms for damage identification in structural health-monitoring applications. This review covers damage detection, localization, classification, extension, and prognosis, as well as the development of smart structures. The literature is systematically reviewed according to the natural steps of a structural health-monitoring system. This review also includes information on the types of sensors used as well as on the development of data-driven algorithms for damage identification.Peer ReviewedPostprint (published version

Modeling and Control of a 7-Level Switched Capacitor Rectifier for Wireless Power Transfer Systems

Wireless power continues to increase in popularity for consumer device charging. Rectifier characteristics like efficiency, compactness, impedance tunability, and harmonic content make the multi-level switched capacitor rectifier (MSC) an exceptional candidate for modern WPT systems. The MSC shares the voltage conversion characteristics of a post-rectification buck-boost topology, reduces waveform distortion via its multi-level modulation scheme, demonstrates tank tunability via the phase control inherent to actively switched rectifiers, and accomplishes all this without a bulky filter inductor. In this work, the MSC WPT system operation is explained, and a loss model is constructed. A prototype system is used to validate the models, showing exceptional agreement with the predicted efficiencies. The modeled MSC efficiencies are between 96.1% and 98.0% over the experimental power range up to 20.0 W. Two significant control loops are required for the MSC to be implemented in a real system. First, the output power is regulated using the modulation of the rectifier\u27s input voltage. Second, the switching frequency of the rectifier must exactly match the WPT carrier frequency set by the inverter on the primary side. Here, a small signal discrete time model is used to construct four transfer functions relating to the output voltage. Then, four novel time-to-time transfer functions are built on top of the discrete time model to inform the frequency synchronization feedback loop. Both loops are tested and validated in isolation. Finally, the dual-loop control problem is defined, closed form equations that include loop interactions are derived, and stable wide-range dual-loop operation is demonstrated experimentally

Wireless Charging of Mobile Systems

This project designs and implements a wireless charging system for small industrial mobile applications. A quick, efficient charging system allows for maximum resource utilization and minimized down time. Resonant inductive power transfer is demonstrated for this purpose. The efficiency of such a system is analyzed, and the results are promising, however there are significant opportunities for improvement