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How to protect the skin from getting sun burnt? The sun can damage your skin e.g. skin cancer. But the sun has a positive effect to the human. The time in sun and the intensity are key values between enjoy the sunbath and having a negative effect to the skin. A smart device like a UV flower could help you to enjoy the sunbath. It measures the UV index around you and gives this information to a smartphone app. The development steps of such a device are described in this paper. The UV flower is made of textile fabrics.
This paper presents a digitally controlled boost converter IC for high output voltage and fast transient applications. Thus, it is well applicable in automotive and industrial environments. The 3V-to-6V input voltage, 6.3V output voltage, 1A boost converter IC is fabricated in a 180nm BCD technology. Digital control enables cost savings, advanced control concepts, and it is less parameter sensitive compared to common analog control. A 90 ns latency, 6-bit delay line ADC operates with a window concept, meeting high resolution requirements, e.g. in car battery applications. An output voltage live tracking is included for extending the ADC conversion window. A charge pump DAC provides high resolution, monotonicity, and short 128 ns conversion time. Further, a standard digital PI controller is enhanced by a simple but effective ΔV/Δt-intervention control. It results in 2.8x reduced output voltage deviations in case of load steps, scaling down the output capacitor value by the same factor.
Managers recognize that software development project teams need to be developed and guided. Although technical skills are necessary, non-technical (NT) skills are equally, if not more, necessary for project success. Currently, there are no proven tools to measure the NT skills of software developers or software development teams. Behavioral markers (observable behaviors that have positive or negative impacts on individual or team performance) are beginning to be successfully used by airline and medical industries to measure NT skill performance. The purpose of this research is to develop and validate the behavior marker system tool that can be used by different managers or coaches to measure the NT skills of software development individuals and teams. This paper presents an empirical study conducted at the Software Factory where users of the behavior marker tool rated video clips of software development teams. The initial results show that the behavior marker tool can be reliably used with minimal training.
The level shifter and the floating gate supply for high-side transistors are a major challenge in high-voltage DCDC converters. This paper presents a high speed and power-efficient level shifter for voltages of up to 50V, suitable for both PMOS and NMOS power FETs. A switching node falling edge detection allows both, a sensitive and safe signal detection. This enables a robust operation during steep dv / dt transitions and a power consumption as low as 4.1 pJ per switching cycle, which is a reduction of more than 40% compared to prior art. An active clamping circuit prevents common mode displacement currents into the high-side supply. The level shifter is implemented in a 180nm BiCMOS technology. Measurements confirm a 50V 120MHz high-speed operation of the level shifter with a rising / falling propagation delay of 1.45 ns / 1.3 ns, respectively. The dv / dt robustness has been confirmed by measurements for transitions up to 6V/ ns.
Size and cost of a switched mode power supply can be reduced by increasing the switching frequency. The maximum switching frequency and the maximum input voltage range, respectively, is limited by the minimum propagated on-time pulse, which is mainly determined by the level shifter speed. At switching frequencies above 10 MHz, a voltage conversion with an input voltage range up to 50 V and output voltages below 5 V requires an on-time of a pulse width modulated signal of less than 5 ns. This cannot be achieved with conventional level shifters. This paper presents a level shifter circuit, which controls an NMOS power FET on a high-voltage domain up to 50 V. The level shifter was implemented as part of a DCDC converter in a 180 nm BiCMOS technology. Experimental results confirm a propagation delay of 5 ns and on-time pulses of less than 3 ns. An overlapping clamping structure with low parasitic capacitances in combination with a high-speed comparator makes the level shifter also very robust against large coupling currents during high-side transitions as fast as 20 V/ns, verified by measurements. Due to the high dv/dt, capacitive coupling currents can be two orders of magnitude larger than the actual signal current. Depending on the conversion ratio, the presented level shifter enables an increase of the switching frequency for multi-MHz converters towards 100 MHz. It supports high input voltages up to 50 V and it can be applied also to other high-speed applications.
A high-voltage replica based current sensor is presented, along with challenges and design techniques which are rarely discussed in literature so far. The performance is evaluated by detailed small signal and large signal analysis. By dedicated placing of high-voltage cascode devices, while keeping as many low-voltage devices as possible, a high gain-bandwidth product is achieved. A decoupling and biasing circuit is introduced which improves the response time of the current sensor at on/off transitions by a factor of five. The current sensor is implemented in a 180nm HV BiCMOS technology. The sensor achieves a DC loop gain of 83 dB and a gain-bandwidth product of 7 MHz. With the proposed techniques, the gain-bandwidth product is increased by a factor of six. The measurable current range is between 60mA and 1.5 A. The performance is demonstrated in a 500 kHz buck converter at an input voltage of 40V. The overall circuit concept is suitable for 100V and beyond, enabling high performance power management designs including switched mode power supplies and motor applications.
A 3D face modelling approach for pose-invariant face recognition in a human-robot environment
(2017)
Face analysis techniques have become a crucial component of human-machine interaction in the fields of assistive and humanoid robotics. However, the variations in head-pose that arise naturally in these environments are still a great challenge. In this paper, we present a real-time capable 3D face modelling framework for 2D in-the-wild images that is applicable for robotics. The fitting of the 3D Morphable Model is based exclusively on automatically detected landmarks. After fitting, the face can be corrected in pose and transformed back to a frontal 2D representation that is more suitable for face recognition. We conduct face recognition experiments with non-frontal images from the MUCT database and uncontrolled, in the wild images from the PaSC database, the most challenging face recognition database to date, showing an improved performance. Finally, we present our SCITOS G5 robot system, which incorporates our framework as a means of image pre-processing for face analysis.
DC-DC-converters are used in many different applications. Specifying the switching frequency is the most important parameter to calculate component costs and required space. Especially automotive applications of small brushed- or brushless dc-motors and the increasing number of DC-DC-converters have high requirements on the structual space (low box volume). This is of particular importance for automotive converters for the new 48 V board net. Multiplying the frequency by two will reduce the size of the power inductor by half at a given specification for output-voltage ripple. Smaller power inductors result in reduced losses due to smaller series resistance and parasitic capacitance. Furthermore a larger switching frequency decreases the size of the DC link capacitors. The circuit will get more idealized. However, as the switching losses increase with frequency, a DC-DC-converter can only benefit from these advantages if the switching behavior can be improved.
This paper presents an optimization method to increase switching slope and switching frequency of a 3.6 kW 3-phase step-up converter by separating the design and layout process into two parts. The first part is the power stage which carries the load current. It contains the power inductance and the drain-source-channel of the power MOSFETs. The second part is the driver circuit which contains the driver ICs, the gate resistor and the gate input impedance. While the switching slope was measured to be improved by 50 % , the switching time decreased by 20 %. Hence, the switching frequency of the step-up converter could be increased from 100 kHz to 200 kHz without loss increase. By mounting the driver ICs in a piggyback configuration in close proximity to the power stage, the parasitics could be further reduced significantly and 500 kHz switching frequency could be achieved with 97.5 % efficiency.
A 20 V, 8 MHz resonant DCDC converter with predictive control for 1 ns resolution soft-switching
(2015)
Fast switching power supplies allow to reduce the size and cost of external passive components. However, the capacitive switching losses of the power stage will increase and become the dominant part of the total losses. Therefore, resonant topologies are the known key to reduce the losses of the power stage. A power switch with an additional resonant circuit can be turned on under soft-switching conditions, ideally with zero-voltage-switching (ZVS). As conventional resonant converts are only efficient for a constant load, this paper presents a predictive regulation loop to approach soft-switching conditions under varying load and component tolerances. A sample and hold based detection circuit is utilized to control the turn-on of the power switch by a digital regulation. The proposed design was fabricated in a 180 nm high-voltage BiCMOS technology. The efficiency of the converter was measured to be increased by up to 16 % vs. worst case timing and by 13 % compared to a conventional hard-switching buck converter at 20 V input voltage and at approximately 8 MHz switching frequency.
This paper presents an integrated synchronous buck converter for input voltages >12V with 10MHz switching frequency. The converter comprises a predictive dead time control with frequency compensated sampling of the switching node which does not require body diode forward conduction. A high dead time resolution of 125 ps is achieved by a differential delay chain with 8-bit resolution. This way, the efficiency of fast switching DCDC converters can be optimized by eliminating the body diode forward conduction losses, minimizing reverse recovery losses and by achieving zero voltage switching at turn off. The converter was implemented in a 180nm high-voltage BiCMOS technology. The power losses were measured to be reduced by 30%by the proposed dead time control, which results in a 6% efficiency increase at VOUT = 5V and 0.2A load. The peak efficiency is 81 %.
The power supply is one of the major challenges for applications like internet of things IoTs and smart home. The maintenance issue of batteries and the limited power level of energy harvesting is addressed by the integrated micro power supply presented in this paper. Connected to the 120/230 Vrms mains, which is one of the most reliable energy sources and anywhere indoor available, it provides a 3.3V DC output voltage. The micro power supply consists of a fully integrated ACDC and DCDC converter with one external low voltage SMD buffer capacitor. The micro power supply is fabricated in a low cost 0.35 μm 700 V CMOS technology and covers a die size of 7.7 mm². The use of only one external low voltage SMD capacitor, results in an extremely compact form factor. The ACDC is a direct coupled, full wave rectifier with a subsequent bipolar shunt regulator, which provides an output voltage around 17 V. The DCDC stage is a fully integrated 4:1 SC DCDC converter with an input voltage as high as 17 V and a peak efficiency of 45 %. The power supply achieves an overall output power of 3 mW, resulting in a power density of 390 μW/mm². This exceeds prior art by a factor of 11.
The presented wide-Vin step-down converter introduces a parallel-resonant converter (PRC), comprising an integrated 5-bit capacitor array and a 300 nH resonant coil, placed in parallel to a conventional buck converter. Unlike conventional resonant concepts, the implemented soft-switching control eliminates input voltage dependent losses over a wide operating range. This ensures high efficiency across a wide range of Vin= 12-48V, 100-500mA load and 5V output at up to 15MHz switching frequency. The peak efficiency of the converter is 76.3 %. Thanks to the low output current ripple, the output capacitor can be as small as 50 nF, while the inductor tolerates a larger ESR, resulting in small component size. The proposed PRC architecture is also suitable for future power electronics applications using fast-switching GaN devices.
In recent years, significant progress has been made on switched-capacitor DC-DC converters as they enable fully integrated on-chip power management. New converter topologies overcame the fixed input-to-output voltage limitation and achieved high efficiency at high power densities. SC converters are attractive to not only mobile handheld devices with small input and output voltages, but also for power conversion in IoE, industrial and automotive applications, etc. Such applications need to be capable of handling widely varying input voltages of more than 10V, which requires a large amount of conversion ratios. The goal is to achieve a fine granularity with the least number of flying capacitors. In [1] an SC converter was introduced that achieves these goals at low input voltage VIN ≤ 2.5V. [2] shows good efficiency up to VIN = 8V while its conversion ratio is restricted to ≤1/2 with a limited, non-equidistant number of conversion steps. A particular challenge arises with increasing input voltage as several loss mechanisms like parasitic bottom-plate losses and gate-charge losses of high-voltage transistors become of significant influence. High input voltages require supporting circuits like level shifters, auxiliary supply rails etc., which allocate additional area and add losses [2-5]. The combination of both increasing voltage and conversion ratios (VCR) lowers the efficiency and the achievable output power of SC converters. [3] and [5] use external capacitors to enable higher output power, especially for higher VIN. However, this is contradictory to the goal of a fully integrated power supply.
An integrated synchronous buck converter with a high resolution dead time control for input voltages up to 48V and 10MHz switching frequency is presented. The benefit of an enhanced dead time control at light loads to enable zero voltage switching at both the high-side and low-side switch at low output load is studied. This way, compact multi-MHz DCDC converters can be implemented at high efficiency over a wide load current range. The concept also eliminates body diode forward conduction losses and minimizes reverse recovery losses. A dead time resolution of 125 ps is realized by an 8-bit differential delay chain. A further efficiency enhancement by soft switching at the high-side switch at light load is achieved with a voltage boost of the switching node by dead time control in forced continuous conduction mode. The monolithic converter is implemented in an 180nm high-voltage BiCMOS technology. At V IN = 48V, V OUT = 5V, 50mA load, 10MHz switching frequency and 500 nH output inductance, the efficiency is measured to be increased by 14.4% compared to a conventional predictive dead time control. A peak efficiency of 80.9% is achieved at 12V input.
More and more power electronics applications utilize GaN transistors as they enable higher switching frequencies in comparison to conventional Si devices. Faster switching shrinks down the size of passives and enables compact solutions in applications like renewable energy, electrical cars and home appliances. GaN transistors benefit from ~10× smaller gate charge QG and gate drive voltages in the range of typically 5V vs. ~15V for Si.
The digitization of factories will be a significant issue for the 2020s. New scenarios are emerging to increase the efficiency of production lines inside the factory, based on a new generation of robots’ collaborative functions. Manufacturers are moving towards data-driven ecosystems by leveraging product lifecycle data from connected goods. Energy-efficient communication schemes, as well as scalable data analytics, will support these various data collection scenarios. With augmented reality, new remote services are emerging that facilitate the efficient sharing of knowledge in the factory. Future communication solutions should generally ensure connectivity between the various production sites spread worldwide and new players in the value chain (e.g., suppliers, logistics) transparent, real-time, and secure. Industry 4.0 brings more intelligence and flexibility to production. Resulting in more lightweight equipment and, thus, offering better ergonomics. 5G will guarantee real-time transmissions with latencies of less than 1 ms. This will provide manufacturers with new possibilities to collect data and trigger actions automatically.
Software and system development is complex and diverse, and a multitude of development approaches is used and combined with each other to address the manifold challenges companies face today. To study the current state of the practice and to build a sound understanding about the utility of different development approaches and their application to modern software system development, in 2016, we launched the HELENA initiative. This paper introduces the 2nd HELENA workshop and provides an overview of the current project state. In the workshop, six teams present initial findings from their regions, impulse talk are given, and further steps of the HELENA roadmap are discussed.
The 21st century: an era where emojis and hashtags find their way into every sentence, where taking selfies, live tweeting and mining bitcoin are the norm, and where Insta-culture dictates what we say and do. This is the era into which the digital native was born. With so many changes in every aspect of our lives, how is it that one of the most influential aspects, our education, has remained unchanged? Our education system not only fails to appeal to today’s students, but more importantly, it fails to equip them with the skills required in the 21st Century. It is thus of no surprise that industries feel graduates entering the workplace lack skills in critical thinking, problem solving and self-directed learning. AI, machine learning and big data: Tools and mechanisms we so eagerly incorporate to create smart factories yet are hesitant to use elsewhere. Gamification and games have shown great results in education and training; with most research suggesting a stronger focus on personalization and adaptation. When combined with analytics and machine learning, the potential of games is yet to be realized. A real-time adaptive game would not only always present an appropriate degree of challenge for the individual but would allow for a shift in focus from the recitation of facts, to the application of information filtered to solve the particular problem at hand. South Africa, a country faced with a severe skills gap, could benefit greatly from games. If used correctly, they may just offer a desperately needed contribution toward equipping both current and future employees with the skills needed to survive in the 21st century. This paper explores the feasibility of using such games for enhanced knowledge dissemination and the upskilling of the workforce.
Modern power transistors are able to switch at very high transition speed, which can cause EMC violations and overshoot. This is addressed by a gate driver with variable gate current, which is able to control the transition speed. The key idea is that the gate driver can influence the di/dt and dv/dt transition separately and optimize whichever transition promises the highest improvement while keeping switching losses low. To account for changes in the load current, supply voltage, etc., a control loop is required in the driver to ensure optimized switching. In this paper, an efficient control scheme for an automotive gate driver with variable output current capability is presented. The effectiveness of the control loop is demonstrated for a MOSFET bridge consisting of OptiMOS-T2™devices with a total gate charge of 39nC. This bridge setup shows dv/dt transitions between 50 to 1000ns, depending on driving current. The driver is able to switch between gate current levels of 1 to 500mA in 10/15ns (rising/falling transition). With the implemented control loop the driver is measured to significantly reduce the ringing and thereby reduce device stress and electromagnetic emissions while keeping switching losses 52% lower than with a constant current driver.
Today 40 Gbps is in development at IEEE 802.3bq over four pair balanced cabling. In this paper, we describe a transmission experiment of 25 Gbps enabling either a single pair transmission of 25 Gbps over a 30 meter balanced cabling channel, or a 100 Gbps transmission via a four-pair balanced channel. A scalable matrix modeling tool is introduced which allows the prediction of transmission characteristics of a channel taking mode conversion into account . We applied this tool to characterize PCB-channels including the magnetics and PCB for a four-pair 100 Gbps transmission. We evaluated prototype cables and connecting hardware for frequencies up to 2 GHz and beyond. Finally we investigated possible line encoding schemes and provide measurement results of a transmission over 30 m with a data rate of 25 Gbps per twisted pair.