Texas Instruments (Germany)

In this work, detailed analysis and discussion on the design of state-of-the-art enhancement and depletion-mode (E/Dmode) GaN power switching transistors considering application and reliability are presented. Key challenges and issues during the development phase are elaborated with a summary of potential solutions at device and circuit system levels providing useful technical reference for a designer using GaN device for targeting power electronics application with high energy efficiency and robustness.

Abstract This chapter presents a comprehensive performance comparison between power converter ICs in GaN and silicon. Beginning with a comparison table of state-of-the-art monolithic high-voltage converter ICs the chapter investigates several different aspects. The GaN IC of this work shows the smallest die size with integrated HV power transistor and is even smaller than most silicon implementations of the controller only. A study explores the trade-off between efficiency and power density. It includes parameters such as switching frequency, inductor values, and ratings. With 95.6% the presented power converter ICs in GaN shows the highest peak efficiency of converters with a fully integrated power stage. Thanks to the fast-switching GaN integration the low component count and small passive component size results in a power density up to \({44 {\mathrm {W/}}{\textrm{in}}^3}\), which is the highest reported in comparison to the state-of-the-art in this voltage and power class. The results can be transferred to other GaN converters and applications spaces.KeywordsGaN vs. SiliconGaN integrationBuck converterLow-side buckLED driverEfficiencyLoss mechanismLoss comparisonSwitching lossesConduction lossesTurn-on energyLoss distributionPower inductorSwitching frequencyPower densityControl accuracyDesign trade-offBill of materials

Abstract This chapter describes the motivation, scope, and outline of the book. Gallium nitride (GaN) as a wide bandgap material enables compact and efficient power electronics. Since the GaN HEMT a lateral device, the high-voltage GaN switch can be combined with other passive and active devices on the same die. This will enable power management integrated circuits (PMICs) that combine power with sensing and control loop circuits. However, monolithic GaN technology is not yet mature in various aspects including parameter variations and analog performance (matching, etc.). As a main challenge, GaN technology lacks a suitable p-type device. The presented research contributes to the development of solutions for reducing the global electric power consumption as well as the overall cost of offline power converters. The book deals in detail with the following main topics: (1) Introduction into monolithic GaN process technology with a focus on the similarities and differences to traditional silicon technologies. (2) The gate loop challenge with GaN transistors due to tight gate voltage requirements and different approaches to ensure a safe operation. (3) Measurement-based characterization of technology properties for analog, digital, and mixed-signal circuit design. (4) Design and implementation of a monolithic buck converter IC in a 650V e-mode GaN technology. (5) Comparison between the designed GaN-based converter and a commercially available silicon converter based on comprehensive experimental characterization and analysis.KeywordsPower electronicsGaNOffline convertersPersonal electronicsWide bandgapGaN integrationMarket overviewShipping numbersHigh efficiencyGlobal energy consumptionUSB PD

This paper discusses several challenges in the design of non-inverting buck-boost regulators. These range from the design of control loop to operation in various regions and associated issues. Several novel schemes are introduced like a universal timer which could work in all the regions of buck-boost, an adaptive region detector which provides optimum point of region-transition independent of input and output voltage measurements or load current and a simple state machine controlled trapezoidal regulation which enables efficient switching. These enable a peak current mode control with adaptive off-time to be maintained throughout all the regions preventing control loop discontinuities. All the ideas presented here are realized on a silicon integrated circuit. Subsequently these concepts are validated and proven through rigorous LAB analysis leading to a commercially usable product which generates adjustable outputs in the range of 1.8V to 5.2V from input voltages in the range of 1.3V to 5.5V.

Regardless of its functionality, there is no IC-compatible process to pattern platinum. This can be attributed to the inertness of the noble metal. Pt survives extreme conditions, and is used in electrochemical, temperature, and gas sensors. In this paper, we introduce a process enabling Pt structures of 1 μm thickness and submicron feature size on 200mm wafers. It is the industry's first with focus on high process control while eliminating contamination issues. This is achieved by locally alloying the Pt with a sacrificial Al layer. The so-formed PtAl <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is then removed by a selective wet-etch, which leaves a uniform Pt structure. The process is VLSI compatible, and can be adapted to any semiconductor fab to have a platinum processing capability. Pt as a third metal besides Al and Cu is a significant enabler for IC sensor technology.

This letter introduces a fully integrated hybrid multiratio resonant dc-dc converter implemented in a 130-nm BCD process. With a 3.0-4.5 V input voltage range it is fully compatible with Li-ion batteries. It provides output voltages of 1.5-1.8 V with an output current range of 500 μA-120 mA, suitable for wearable applications. The proposed switch conductance regulation (SwCR) achieves a flat converter efficiency across the full load range together with a small output voltage ripple of <; 35 mV. The converter achieves 85% peak efficiency with a total flying capacitance of 2 nF, a 9-nH spiral inductance and 10-nF output capacitance (all onchip). With a small external 10-nH SMD inductance mounted on top of the die, 88.5% peak efficiency is achieved.

It is important to collect data about the risk of transformation of an actinic keratosis (AK) lesion into squamous cell carcinoma (SCC) after a single photodynamic therapy (PDT) with 5-ALA patch for a longer follow-up period under daily routine. The purpose of this non-interventional study (NIS) was to collect data on the frequency of occurrence of SCCs in the treated area during an interval of 2years after a single 5-ALA patch-PDT. This prospective observational case-only study included patients with mild AK lesions on the head and face treated with 5-ALA patch-PDT according to the Summary of Product Characteristics (SPC). In 370 patients, the risk of transformation of their treated AK lesion into SCC was 0.073% with its exact 95% confidence interval using the Poisson distribution of [0.009%, 0.262%]. The rate of complete clinical clearance on lesion basis after 3months was 84.3%. The efficacy and the safety results show no observation of an increased risk for conversion of an AK into a SCC 2years after a single 5-ALA patch-PDT. Additionally, the high clinical complete remission rate under routine conditions is comparable to the rates observed in the approval trials.

Despite substantial and successful projects for structural genomics, many proteins remain for which neither experimental structures nor homology-based models are known for any part of the amino acid sequence. These have been called "dark proteins," in contrast to non-dark proteins, in which at least part of the sequence has a known or inferred structure. It has been hypothesized that non-dark proteins may be more abundantly expressed than dark proteins, which are known to have much fewer sequence relatives. Surprisingly, the opposite has been observed: human dark and non-dark proteins had quite similar levels of expression, in terms of both mRNA and protein abundance. Such high levels of expression strongly indicate that dark proteins-as a group-are important for cellular function. This is remarkable, given how carefully structural biologists have focused on proteins crucial for function, and highlights the important challenge posed by dark proteins in future research.

This paper presents a temperature-insensitive magnetic sensor system for contactless current measurements. To simultaneously achieve wide bandwidth and low noise, the proposed system employs a multi-path structure with a set of spinning current Hall sensors in its low-frequency path and a set of pick-up coils in its high-frequency path. The Hall sensors and pick-up coils are used in a differential sensing arrangement that naturally rejects common-mode magnetic field interference, e.g., due to the earth’s magnetic field. A common-mode ac reference field can then be used to continuously stabilize the sensitivity of the Hall sensors, which, unlike that of the pick-up coils, is quite temperature dependent. In this design, the ripple reduction loops in the Hall sensor readout are implemented in a discrete-time manner, and so occupy 20% less area than a previous continuous-time implementation. Over a −45 °C to 105 °C temperature range, the proposed system reduces the Hall sensor drift from 22% to 1%, which corresponds to a temperature coefficient of 76 ppm/°C.

Microcontrollers (MCUs) serve a central role in the design of IoT leaf nodes. A typical microcontroller comprises of a processing core, program and data memory, serial communication interfaces, general purpose IO (GPIOs) ports, comparators and ADCs, clock generation and power regulators. Microcontrollers have modest clock frequencies and memory capacities, keeping the IC cost low. High level of integration helps improves performance, lowers power and helps achieve a small form factor. All of these are critical in the design of ICs for IoT applications. This chapter focuses on the design of low power microcontrollers using two Texas Instruments (TI) microcontrollers as examples. Both microcontrollers feature embedded Ferro-electric RAM (FRAM) as a low power non-volatile unified data and program memory. Low write power non-volatile memory with high write endurance (number of write cycles) is critical in IoT applications that feature data logging. FRAM has low power writes at 1.5 V, practically unlimited write endurance (>1015), and high yields with millions of shipped parts. In the following sections we describe analog, digital and system design techniques that help achieve the low power metrics in TI microcontrollers.