Browse Topic: Transistors
Researchers at the University of California, Irvine, and New York’s Columbia University have embedded transistors in a soft, conformable material to create a biocompatible sensor implant that monitors neurological functions through successive phases of a patient’s development.
Boosting the performance of solar cells, transistors, LEDs, and batteries will require better electronic materials, made from novel compositions that have yet to be discovered.
A new low-cost, scalable technology can seamlessly integrate high-speed gallium nitride transistors onto a standard silicon chip. Massachusetts Institute of Technology, Cambridge, MA The advanced semiconductor material gallium nitride will likely be key for the next generation of high-speed communication systems and the power electronics needed for state-of-the-art data centers. Unfortunately, the high cost of gallium nitride (GaN) and the specialization required to incorporate this semiconductor material into conventional electronics have limited its use in commercial applications.
Researchers at Rice University have found a new way to improve a key element of thermophotovoltaic (TPV) systems, which convert heat into electricity via light. Using an unconventional approach inspired by quantum physics, Rice engineer Gururaj Naik and his team designed a thermal emitter that can deliver high efficiencies within practical design parameters.
Researchers at the University of California, Irvine and New York’s Columbia University have embedded transistors in a soft, conformable material to create a biocompatible sensor implant that monitors neurological functions through successive phases of a patient’s development.
United States microchip fab plants can cram billions of data-processing transistors onto a tiny silicon chip, but the “clock,” which times the transistors’ operations, must be made separately, which creates a flaw in chip security as well as the supply line. However, a new approach uses commercial chip fab materials and techniques to fabricate specialized transistors to serve as the building block of the timing device.
After announcing a ferroelectric semiconductor at the nanoscale thinness required for modern computing components, a University of Michigan team has demonstrated a reconfigurable transistor using that material. The study is featured in Applied Physics Letters.
A Northwestern University research team has developed a revolutionary transistor that is expected be ideal for lightweight, flexible, high-performance bioelectronics. The electrochemical transistor is compatible with blood and water and can amplify important signals.
Ultrafine particles, in particular solid sub-100 nm particles pose high risks to human health due to their high lung deposition efficiency, translocation to all organs including the brain and their harmful chemical composition; due to dense traffic, the population in urban environments is exposed to high concentrations of those toxic air contaminants, despite these facts, they are still widely neglected. Therefore, the EU-Commission set up a program for clean and competitive solutions for different problem areas which are regarded to be hotspots of such particles. HORIZON AeroSolfd is an EU project, co-funded by Switzerland that will deliver affordable, adaptable, and sustainable retrofit solutions to reduce exhaust tailpipe emissions from petrol engines, brake emissions and pollution in semi-closed environments. VERT, a Swiss based international industry organization, has a long research history in the field of nanoparticle filtration and it is in charge of reducing tailpipe emissions of gasoline vehicles by using the best available retrofit filtration technology (BAT). VERT will apply the newest high-efficient GPF technology in three high mileage fleets, in Germany, Switzerland and Israel. The project will also serve as a platform to continue research on PN emissions as well as on secondary emissions from GDI and PFI petrol engines. In addition, the “high emitter phenomena” will be further analysed with a NPTI testing campaign of 1000 gasoline vehicles, including GDI, PFI and GPF equipped vehicles.
In modern electronics, a lot of heat is produced as waste during usage — hence why in-use devices become excessively hot and require cooling solutions. Over the last decade, the concept of managing such heat via electricity has been tested, leading to the development of electrochemical thermal transistors.
The molecules in our bodies are in constant communication. Some of these molecules provide a biochemical fingerprint that could indicate how a wound is healing, whether or not a cancer treatment is working, or whether a virus has invaded the body. If we could sense these signals in real time with high sensitivity, then we might be able to recognize health problems faster and even monitor disease as it progresses.
Two-dimensional materials, which consist of just a single layer of atoms, can be packed together more densely than conventional materials, so they could be used to make transistors, solar cells, LEDs, and other devices that run faster and perform better. One issue holding back these next-generation electronics is the heat they generate when in use. Conventional electronics typically reach about 80 °C, but the materials in 2D devices are packed so densely in such a small area that the devices can become twice as hot. This temperature increase can damage the device.
The Grainger College of Engineering at the University of Illinois at Urbana–Champaign was established in 1868. The department has historically spearheaded worldwide innovation in technology with inventions such as the transistor, the integrated circuit, the LED, the first web browsers (Mosaic and Netscape), and (JavaScript) — all produced by students, faculty, or alumni of the college.
Developers of aerospace and defense systems need RF power amplifiers (PAs) to perform much better across both existing and emerging applications such as military 5G and satellite communication. Systems need to meet higher gain targets but not if it comes with any increases in cost and complexity, or size and weight. As systems move to higher-order modulation schemes, they also must deliver adequate linearity and efficiency in an environment that is even more susceptible to distortion than was the case with earlier schemes. Reducing board space is another critical issue that has required challenging peak-to-average power ratio (PAPR) tradeoffs
Pulse shaping, as it is done today, is an effort to fix fidelity issues caused by the transmitting amplifier and is accomplished by a combination of imperfect methods, most external to the amplifier. This article will explain a new approach that matches input pulse signal shape, minimizing droop, overshoot, ringing, and rise and fall times.
A new composition of germanosili-cate glass created by adding zinc oxide has properties good for lens applications. The new family of zinc germanosilicate glass has a high refractive index comparable to that of pure germania glass. Samples showed high transparency, good ultraviolet-shielding properties, and good glass forming ability, making them suitable for lens applications. Germanosilicate glass is essential in the manufacture of optical amplifiers, waveguides, and solid-state lasers.
The insulated-gate bipolar transistor (IGBT) is the most important part of a power converter. The heat generated during operation will cause the junction temperature of the IGBT to rise above ambient temperature. The junction temperature must stay within its predefined limit to ensure reliable operation. A properly designed cooling system is crucial for the overall operation, and an accurate prediction of power loss is critical in the design of a good thermal system. In this paper, a pulse-width modulation (PWM) full-bridge converter is designed for free-piston engine generators (FPEGs), and a low-cost forced-air cooling system is used for heat dissipation. For the converter to choose the IGBT module or discrete IGBT as the switching device, loss and thermal analyses are carried out. The loss analysis model of the converter is established, which considers the influence of the IGBT parasitic capacitance and gate driver voltage on the switching losses. The accuracy of the loss analysis model is verified by comparison with experiments. The converter thermal analysis, in which a three-dimensional (3-D) thermal model is built and is carried out based on the loss analysis data. The results of loss analysis and thermal analysis show that, compared with discrete IGBT, the use of an IGBT module can improve the efficiency of the converter and is more conducive for heat dissipation.
Researchers devised and tested a highly sensitive method of detecting and counting defects in transistors — a matter of urgent concern to the semiconductor industry as it develops new materials for next-generation devices. These defects limit transistor and circuit performance and can affect product reliability.
Although wireless charging pads already exist for smartphones, they only work if the phone is sitting still. For cars, that would be just as inconvenient as the current practice of plugging them in for an hour or two at charging stations.
Researchers at Chalmers University of Technology have developed an optical amplifier that they expect will revolutionize both space and fiber communication. The new amplifier offers high performance, is compact enough to integrate into a chip just millimeters in size, and crucially, does not generate excess noise.
Electrically conducting polymers have made possible the development of flexible and lightweight electronic components such as organic biosensors, solar cells, light-emitting diodes, transistors, and batteries. The electrical properties of the conducting polymers can be tuned using a method known as “doping.” In this method, various dopant molecules are added to the polymer to change its properties. Depending on the dopant, the doped polymer can conduct electricity by the motion of either negatively charged electrons (an n-type conductor) or positively charged holes (a p-type conductor).
Ultrathin, flexible computer circuits have been an engineering goal for years but technical hurdles have prevented the degree of miniaturization necessary to achieve high performance. Now, researchers have invented a manufacturing technique that yields flexible, atomically thin transistors less than 100 nanometers in length — several times smaller than previously possible.
To design better power converters with enhancement-mode Gallium Nitride high-electron-mobility transistor (eGaN HEMT) for emerging applications such as Electric Vehicles (EV), it is essential to model their switching transients and loss accurately. Analytical modeling has proved to be an effective approach to study the transistor’s dynamic behaviors and analyze the switching energy loss during the turn-on and turn-off transients. Furthermore, it helps to understand the essential factors that influence the switching transients and loss calculation. The accuracy of the analytical model mainly depends on the equivalent circuits and the parasitic parameters inside the transistor packaging and external circuits under different switching stages. It is always challenging to extract the parasitic parameters accurately due to its natural character of nonlinearity and complex correlation during the switching transients. In this article, a comprehensive analytical model is proposed considering both transistors in the same bridge-leg and all necessary parameters that potentially affect the switching transients, especially when the unique reverse conduction of eGaN HEMT happens. New parasitic extraction methods are utilized and evaluated within the proposed model. Detailed stages of turn-on and off transients are also presented and verified against simulation program with integrated circuit emphasis (SPICE) simulation and experiment. In the end, the proposed model is applied for accurate switching loss calculations.
Like commercial communications, radar and electronic warfare (EW) systems must now function successfully in an increasingly crowded and, therefore, unpredictable electromagnetic spectrum operations environment (EMSO). In fact, the radio frequency (RF) spectrum grows only more congested as these intentional aerospace defense systems intersect with everything else that might interfere, such as terrestrial broadcast signals, different generations of cellular communications, and satellite communications. Modern threats and countermeasures flood the modern EM spectral environment with thousands of emitters, including radios, wireless devices, and radar transmissions. This, in conjunction with advanced digital signal processing (DSP), creates a dramatically complex electromagnetic spectrum.
Performance of solar cells and other electronic devices, such as transistors, can be improved greatly if carrier mobility is increased. Si and Ge have Type-II bandgap alignment in cubically strained and relaxed layers. Quantum well and superlattice with Si, Ge, and SiGe have been good noble structures to build high electron mobility layer and high hole mobility layers.
NASA Glenn has developed a method to correct for variations in transistor threshold voltage due to die location on the wafer for silicon carbide (SiC) op amps, enabling improved electrical circuits for sensor signal conditioning in harsh environments. Important system-level benefits are enabled by improved performance data from sensor circuitry mounted within very hot gas turbine flows or the primary coolant loop of a nuclear reactor, for example.
Acoustical studies of atmospheric events like convective storms, tornadoes, shear-induced turbulence, micro-bursts, acoustic gravity waves, and hurricanes over the past 50 years have established that these events are strong emitters of infrasound. Current methods to forecast near-term weather phenomenon is electromagnetic (EM)-based radar and data from radiosondes.
Superconductors — materials that conduct electricity without resistance — provide a macroscopic glimpse into quantum phenomena, which are usually observable only at the atomic level. Superconductors are found in medical imaging, quantum computers, and cameras used with telescopes. But often, they are expensive to manufacture and prone to error from environmental noise.
All of our most-used electronic devices rely on increasingly smaller microchips. One of the biggest hurdles to putting more circuits and power onto a smaller chip is managing the heat. As chips become smaller, heat increases exponentially. Not only are there more transistors in a given area — which generates more heat in a small space — but they also are closer together, making it harder for heat to dissipate.
A hacker can reproduce a circuit on a chip by discovering what key transistors are doing in a circuit — but not if the transistor type is undetectable. Engineers have demonstrated a way to disguise which transistor is which by building them out of a sheet-like material called black phosphorus. This built-in security measure would prevent hackers from getting enough information about the circuit to reverse-engineer it.
The main objective of the RadCNT program was the characterization of fundamental mechanisms and charge transport phenomena governing the interactions between ionizing and non-ionizing radiation with carbon-based (nanotube and graphene) field-effect transistors (FETs) devices and integrated circuits (ICs). This effort was supported through the fabrication of aligned single-walled carbon nanotubes (SWCNT) FETs at the University of Southern California’s (USC) Nanotechnology Research Laboratory and through a collaboration with the Naval Research Laboratories (NRL) for radiation testing and expertise in radiation effects characterization.
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