A Four Quadrant Switch (FQS) provides bidirectional current carrying and bidirectional voltage blocking capability. Integrated FQS can enable significant size, complexity, and cost savings compared to traditional implementations that use multiple components resulting in limited performance and high cost. We demonstrate GaN based integrated FQS technology. The lateral GaN HEMT technology combined with a common drain configuration allows us to share the high-voltage region and results in a 40% reduction in the die size compared to two discrete GaN switches. The integrated FQS is a 60mOhm switch assembled in a TO247 package with a floating tab. We show excellent bidirectional current conduction and voltage blocking with symmetric current-voltage and capacitance-voltage behavior. The $R_{ON}$. $Q_{g}$ is 80% lower and $R_{ON}$. $Q_{rr}$ is 30% lower than state$- of- art SiC MOSF$ETs resulting in 60% lower switching losses.

BACKGROUND: Subjects with thoracic scoliosis were an important group in early studies of noninvasive ventilation (NIV). The aim of this study was to describe current rates of initiation of NIV and survival after initiation in this population. METHODS: This study included patients identified as having thoracic scoliosis and established between 1993 and 2018 on home NIV. Patients with scoliosis secondary to neuromuscular disease (other than poliomyelitis) were excluded. Survival rates were calculated for various time intervals up to 25 y. RESULTS: A total of 53 subjects with thoracic scoliosis were successfully established on NIV. P-aCO2 levels prior to starting NIV were 55 +/- 23 mm Hg. FVC was 0.5 +/- 0.1 L, 18.5 +/- 9% of predicted, with a Cobb angle of 101 +/- 3.5 degrees. The 5-, 10-, 15-, 20-, and 25-y survival rates were 96%, 88%, 61%, 46%, and 39%, respectively. At the time of death, subjects had been on home NIV for 9.2 +/- 5.1 y and were 75.5 +/- 9.2 y old. There was no significant correlation between mortality and age at time of commencing home NIV, initial arterial blood gas results, FVC, or Cobb angle. There was no significant difference in survival between those with and without poliomyelitis. In 8 of 10 of the most recent years of this survey, subjects with scoliosis have been commenced on home NIV. CONCLUSIONS: Small numbers of subjects with scoliosis continued to present with respiratory failure. Once established on home NIV, around 40% survived >= 25 y. Long-term care will be needed for many years to come for this patient population.

This manuscript proves maturity of GaN-on-Si technology for the world’s first highly reliable 650V GaN HEMT [2],[3],[4],[5],[6],[7],[8] by demonstrating three years of manufacturing data of since ramp. This technology was initially developed in a pilot line in Transphorm Goleta, CA and then later ported into a Si-CMOS compatible 6-inch foundry at AFSW(Aizu Fujitsu Semiconductor Wafers Solution Ltd). Data set generated from over three thousand wafers worth of data spread over three generations of technology nodes covering multiple products and packages post qualification is presented Silicon manufacturing processes are employed including gold- free, and avoiding the use of evaporation/liftoff typical to compound semiconductors. Best practice of defect detection, failure analysis and process control methods from Si manufacturing industry have been employed to maintain and improve yield for this new technology. Probe yield and line yield for the GaN process now matches that of mature Si-CMOS process running in the same fabrication facility[1]. Wide bandgap high-speed and high- voltage GaN devices significantly reduce the system size and improve energy efficiency of power conversion in all areas of electricity conversion, ranging from PV inverters to electric vehicles. The results below demonstrates that GaN high volume production is now a reality.

To facilitate development of tailored management strategies for bait species within Knysna Estuary (South Africa), demand for bait, harvesting activity and perceptions around conservation among recreational and subsistence bait fishers were investigated. In 2015 and 2016, bait collectors were interviewed (n = 84) and observed (n = 167) during low tides at six sites during peak and off-peak holiday periods. Significant associations among subsistence and recreational fishers and their favoured bait species, collecting spots and method, frequency of collection, views on regulations and desired daily limit for mudprawns suggest differences that may warrant different management strategies. Furthermore, observed methods and duration of bait collecting differed according to site, suggesting spatial variation in baiting pressures. Subsistence fishers potentially collect more mudprawns more frequently than do recreational fishers and consequently have a greater impact on mudprawn populations. By contrast, recreational fishers collect more polychaete worms, but because they are mainly active during holidays, their impact on these species may be localised and not yet critical. Most subsistence fishers would like increased daily bag limits, to sell bait and would welcome a rotational zonation scheme to replace the current permanent exclusion zone. The merits and disadvantages of these management options and suggestions are discussed.

Taking advantages of the wide-band-gap properties and the manufacturability of Si wafers, GaN-on-Si power transistors have been a focus in power electronics because of the high conversion efficiency. After the initial production of GaN devices and related application adoptions in the commercial market, the efforts are extended to higher working voltages and higher quality levels. Here we report the latest progress of GaN power HEMTs at Transphorm Inc. For higher power applications, the first 900V GaN product has been developed and successfully passed JEDEC qualification with 720V HTRB. Meanwhile, 650V product has passed automotive AEC-Q101 qualification as the first in the industry. In the failure rate analysis, both voltage acceleration and temperature acceleration have been employed for characterization. The study of the early lifetime failure showed a PPM about 10 (an annual failure rate of 0.001%) at typical working condition of 480V and 100C. This quality level meets automotive application requirements.

Adoption of any semiconductor technology by the power conversion market requires the understanding of fundamental failure modes, acceleration factors and reliability statistics. This study shows how GaN products from Transphorm can meet this challenge, especially in the critical High Voltage Off State (HVOS) reliability stress test. The anticipated failure rate during a product's first 10 to 20 years of use is of particular interest as it has direct impact on warranty costs. This market requirement can be addressed by testing to failure statistically significant samples of devices, and analyzing the data with appropriate models. The methods developed for measuring GaN reliability on large samples will be discussed, which are wholly based on existing industrial and automotive standards. The resulting data can be used to supplement qualification testing results when the failure modes and acceleration factors are well understood.

Electroless nickel immersion gold (ENIG) has emerged as a leading surface finish for under bump metallization (UBM). An ENIG surface typically exhibits excellent planarity, good electrical characteristics, wettability for solder, and Al-wire bondability. Reliability and performance of ENIG systems have been extensively reported at temperatures below 250 degrees C, however information is not readily available about its reliability at higher temperatures. In this paper, thermal behavior of electroless Ni/Au and electroless Ni/Pd/Au during solder reflow processing at temperatures of up to 350 degrees C was characterized. Wafer level evaluations were completed using optical microscopy and FIB cross-sectional SEMs, while packaged devices were subjected to standard reliability tests. Electroless Ni began to exhibit signs of cracking when exposed to temperatures of 350 degrees C under certain conditions. Based on these findings, we propose ENIG material structures and maximum processing temperatures to eliminate cracking. Power devices manufactured with ENIG metallization can be capable of passing JEDEC qualification when implemented with these design parameters.

Adoption of any semiconductor technology by the power conversion market requires an understanding of fundamental failure modes, acceleration factors, and reliability statistics. In this paper we will show how GaN products from Transphorm can meet this challenge, especially in the critical High Voltage Off State (HVOS) reliability stress test. The anticipated failure rate during a product’s first 10 to 20 years of use is of particular interest as it has direct impact on warranty costs. This requires an understanding of both extrinsic and intrinsic failure rates. This market requirement can be addressed by testing to failure statistically significant samples of devices, and analyzing the data, with appropriate models. This paper will discuss the methods developed for measuring GaN reliability on large samples which are wholly based on existing industrial and automotive standards. Further, the paper will discuss how the resulting data can be used to supplement qualification testing results when the failure modes and acceleration factors are well understood. Keywords—GaN, reliability, power electronics, HEMT, FIT, acceleration factor, PPM

• Results• Failures seen in GaN HEMT only•> 99% were catastrophic failures (no increase in leakage)• Acceleration factor (α) is 0.026 V-1 𝑡𝑡𝑓∝ 𝑒− 𝛼𝑉

Bi-directional switches, also called four quadrant switches (FQS), are the basic building blocks in many power converter circuits, such as cyclo-converters, matrix converters etc. Conventional approaches to realize bi-directional switch involves combination of unidirectional controllable blocking device (IGBT or MOSFET) and diode. In this approach, current flows through multiple devices for any direction of current flow. This leads to higher conduction losses. Moreover, use of multiple devices increases system size. The die size and semiconductor losses can be reduced by realizing a bi-directional switch using a single die. Further improvement can be achieved by using Gallium Nitride (GaN) semiconductor. This paper discusses characterization of such a four quadrant GaN switch, made using a single die. Static characterization is performed, where the on-state resistances are obtained along with the output characteristics. A double pulse test setup has been built for characterizing FQS's and the experiments were performed to obtain the turn-on and turn-off switching energies.

Long-term non-invasive ventilation (NIV) was introduced in the 1980s, initially mainly for patients with poliomyelitis, muscular dystrophy (MD) or scoliosis. The obesity-hypoventilation syndrome has since become the commonest reason for referral to most centres providing home-NIV. Patients with MD are numerically a much smaller part of the workload, but as their disease progresses the need for ventilatory support changes and they require regular comprehensive assessment of their condition. We have examined the trend in MD use of home-NIV in our unit over the last 25 years. The number of new referrals appears to be stabilizing at around 20-25 over a 5-year period, equivalent to approximately 0.5 per 100,000 of population per year. The mean age at commencement of home-NIV is now 37.5 years, with 5-year survival rates of 70-75%. Ten-year survival rates are just over 40%. The distance of usual place of residence from our unit is fairly stable, currently at a mean of 27 km. Excellent survival rates mean that patients with MD, while numerically small, are likely to remain an important part of the workload of centres providing home-NIV. Our data should prove useful in the planning of future services for this group of patients.

During non-invasive ventilation (NIV), tidal volume (V-t) will depend upon the difference between inspiratory and expiratory positive airway pressure (IPAP and EPAP, respectively), provided the respiratory muscles are relaxed and the lungs and chest wall therefore move along their passive pressure-volume curves. To test this hypothesis, we studied the effect of increasing EPAP during pressure-controlled modes of NIV in 30 long-term ventilator users (10 each with scoliosis, obesity hypoventilation or neuromuscular disorders). While maintaining the same IPAP, addition of 5 cmH(2)O of EPAP reduced mean V-t by 167 ml; 10 cmH(2)O reduced V-t by 367 ml. This pattern was seen in all three patient groups. EPAP has several potential advantages, for example maintaining upper airway patency, preventing basal atelectasis and facilitating triggering. EPAP does, however, appear to reduce V-t. Decreasing EPAP is an alternative to increasing IPAP if measurements of gas exchange during NIV indicate that ventilation is inadequate.

Manufacturing readiness of the world's first highly reliable 650V GaN HEMT is demonstrated with high process capability (CpK>1.6) for leakage and on resistance. This technology was developed in a Si-CMOS compatible 6-inch foundry and has been demonstrated with over one thousand wafers worth of data spread over two generations of technology nodes covering multiple products and packages collected during ramp up post qualification. Silicon manufacturing processes are employed including gold-free processes that avoid the use of evaporation/liftoff typical to compound semiconductors. Probe yield and Line yield for the GaN process now matches mature Si-CMOS process running in the same fabrication facility. Extended qualification results beyond JEDEC standard are also shown for GaN products for the first time. Products in cascode configuration were tested. Wide bandgap high speed and high voltage GaN devices significantly reduce the system size and improve energy efficiency of power conversion in all areas of electricity conversion, ranging from PV inverters to electric vehicles making the above results significant and making GaN high volume production a reality.

Objectives: Cardiac involvement and/or macroglossia with soft tissue deposits are risk factors for central sleep apnoea (CSA) and obstructive sleep apnoea (OSA), and common features of systemic AL amyloidosis. Little data exist on the occurrence of sleep-disordered breathing (SDB) or recurrent nocturnal hypoxia in amyloidosis, which this study sought to investigate.Methods: A total of 72 consecutive patients with systemic amyloidosis (mean age 69 years and mean BMI 25) were evaluated for occurrence of SDB, by overnight continuous pulse oximetry, and completed Epworth Sleepiness Score (ESS) and STOPBANG questionnaires. Patients included: AL cardiac (AL-C), AL macroglossia (AL-M), AL both (AL-CM) and transthyretin (ATTR).Results: Mean overnight oxygen saturations were 93% (SD +/- 2, 95% CI 87-96) with abnormal oximetry (4% oxygen desaturation index (ODI) >5/hour): AC-C 84%, AL-M 57%, AL-CM 62% and ATTR 47%. NYHA class directly correlated with a higher 4% ODI, NYHA class I vs 3, (p = 0.01). Two-thirds of patients had STOPBANG scores >3 and abnormally high ESS scores (>10) were seen in up to 30% of patients.Conclusion: Recurrent nocturnal hypoxaemia, suggestive of sleep-disordered breathing, is frequent in systemic AL amyloidosis. The higher incidence in cardiac amyloidosis highlights CSA and recurrent hypoxia as possible mechanisms for morbidity/mortality in these cases. A detailed polysomnography study is planned to clarify and further investigate these findings. (C) 2016 Published by Elsevier B.V.

Background Varying rates of oesophageal adenocarcinoma (OAC) complicating Barrett’s oesophagus (BO) have been reported. Recent studies and meta‐analyses suggest a lower incidence, questioning the value of endoscopic surveillance. Aim We aimed to retrospectively examine the rate of OAC, risk factors and causes of death in a prospectively recruited BO cohort. Methods Data from patients with BO from a cohort from 1982–2007 were studied. Patients were subdivided into surveyed, failed to attend surveillance and unfit for surveillance. Standardised mortality ratios (SMR) were calculated for common causes of death. Cox proportional hazards models were used to determine which factors were associated with progression to OAC. Results In total, 671 BO patients (61% male) were studied; 37 (76% male) were diagnosed with OAC. OAC incidence was 0.47% per annum and stable across three decades (1982–1991 0.56%, 1992–2001 0.46%, 2002–2012 0.41% ( p = 0.8)). All‐cause mortality was increased for the whole cohort (SMR 163(95% CI 145–183)). Mortality from OAC appeared higher in patients who failed to attend surveillance (SMR 3216(95% CI 1543–5916)) compared with surveyed (SMR 1753(95% CI 933–2998)) and those unfit for surveillance due to co‐morbidity (SMR 440(95% CI 143–1025)). Multivariable analysis identified low‐grade dysplasia (HR 4.4(95% CI 1.56–12.43), p = 0.005) and length of BO (HR 1.2(95% (1.1–1.3)), p < 0.001)) as associated with OAC. Conclusions Progression to OAC appeared stable over three decades at 0.47% per annum. Patients with BO had a modest increase in all‐cause mortality and a large increase in OAC mortality, particularly if fit for surveillance. Low‐grade dysplasia and the length of the BO segment were associated with developing OAC.

The reliability of 600 V GaN power switches, fabricated in a silicon CMOS foundry, has been demonstrated. JEDEC qualification of cascode packages and the long term reliability of GaN power switches has been estimated for the first and shown to be greater than a million hours. Excellent switched/dynamic on-resistance up to 1000 V and breakdown voltage over 1500 V indicate the suitability of these devices for switching up to 480 V. Detailed data of high temperature reverse bias (HTRB) test is shown. High temperature DC stress test and high voltage off-state stress tests also corroborate the high reliability of these devices. This suite of initial, JEDEC & accelerated stress tests show that GaN-on-silicon power switches are ready for many commercial and industrial applications, would significantly reduce switching losses and system size and will impact all areas of electricity conversion, ranging from tablet chargers to photovoltaic inverters and electric vehicles.

In this paper, we demonstrate 600 V highly reliable GaN high electron mobility transistors (HEMTs) on Si substrates. GaN on Si technologies are most important for the mass-production at the Si-LSI manufacturing facility. High breakdown voltage over 1500 V was confirmed with stable dynamic on-resistance (RON) using cascode configuration package. These GaN HEMT on Si based cascode packages have passed the qualification based on the standards of the Joint Electron Devices Engineering Council (JEDEC) (1-5) for the first time. High voltage acceleration test was performed up to 1150 V. Even considering most conservative failure mechanism, mean time to failure (MTTF) of over 1×107 hours at 600 V was predicted at 80°C. Additional conclusion is that conventional packages such as TO-220 are still suitable for high speed circuit application without using a specific gate driver. Ultimately GaN will significantly reduce conversion losses endemic in all areas of electricity conversion, ranging from power supplies to PV inverters to motion control to electric vehicles, enabling consumers, utilities and governments to contribute towards a more energy efficient world.

With its proven ability to reduce size (form factor) and save energy (high efficiency) Gallium Nitride (GaN) is now no longer a nice to have, it is a must-have for power conversion. In applications ranging from sub 100 watt ultra-compact high frequency adapters to multi kilowatt highly efficient PV inverters, GaN makes it possible to do what Silicon cannot. High voltage GaN on Silicon HEMT switches are now a reality, following successful completion of JEDEC qualification as well as establishment of a high voltage lifetime of >10M hours. A large area (6inch) GaN on Si technology and the ability to manufacture in existing high volume Si foundries makes GaN commercially attractive. We will discuss the commercialization of the 600V GaN HEMT at Transphorm enabled by a superior product, strong IP across the full value chain and a team with deep rooted experience in GaN technology and business. Ultimately GaN will significantly reduce conversion losses endemic in all areas of electricity conversion, ranging from power supplies to PV inverters to motion control to electric vehicles, enabling consumers, utilities and governments to contribute towards a more energy efficient world.