1058 results found, displaying items 1 - 20

I n an idealized diode, no reverse current flows from cathode to anode when the device is reverse-biased. However, with real-world diodes, large amounts of stored charge can flow from the cathode—back through the anode— before the diode enters its blocking state. That stored charge is QRR, and it causes the reverse recovery current (IRR) that flows as the diode transitions from forward to reverse bias. For example, a...

Technological advances lead to tactical advantages. That’s why investments in electronic technology for military applications traditionally run high. Yet those investments can often yield useful breakthroughs as well as dramatic improvements in existing technologies. Military systems such as electronic warfare (EW), signal intelligence (SIGINT), and radar systems receive the most funding. Still, electronic building blocks such as amplifiers, display...

Okay, you want to design an electric car. Whatever kind of motor you decide on, you’re going to want to run it at a pretty high voltage. That means stacking many batteries in series to get to that voltage, which introduces interesting challenges in monitoring and charging circuits as potentials at the negative electrodes rise above system ground. This is not a new problem. But as long as it’s been confined to products like golf carts and nuclear submarines, ...

Switch-mode power supplies (SMPS) continue to replace linear-regulator types in a host of applications. As the need for more efficient electronics accelerates and as a result of their size, weight, and energy-saving advantages, SMPS are being widely used in applications such as LCD TV monitors, PC/ laptop displays, portable electronics chargers, printers, DVD recorders, and even automotive electronics and industrial. Yet because these new SMPS lack the...

Energy production requires state-of-the-art monitoring systems. Of course, these systems require energy of their own to operate. For example, GE Energy recently developed a system that monitors machinery conditions for a field trial at the Nyhamna gas plant in Norway. By harvesting the vibration energy from the machines it monitors, this system’s power supply is inexhaustible. This power supply uses a microgenerator to convert vibrational energy into usable electrical energy....

Once the staple of brute-force power supplies and large industrial and consumer power applications, ultracapacitors are now finding their way into products of all sizes, particularly portables. Also called supercapacitors, these components are notable for capacitance values ranging into the thousands of Farads and fast charge/discharge rates. With the ability to store massive amounts of energy for long periods of time, ultracapacitors behave more like a battery ...

The continuing growth of portable handheld devices has spawned a healthy selection of aftermarket battery pack suppliers. Yet aftermarket vendors may resort to activities that compromise the end-user experience or safety to make the battery packs inexpensive and attractive to those placing purchase orders for replacements. An analysis of several counterfeit batteries revealed a variety of manufacturing and design problems, and we can use these examples to answer...

The continuing evolution toward higher-performance microprocessor units (MPUs) has revolutionized the design of computers large and small. This evolution has generally followed Moore’s law—the semiconductor industry doubles transistor density every two years while increasing performance with each new generation. Increased performance has contributed to a rise in microprocessor chip power dissipation and power density. An example of the...

Imagine using your laptop, non-stop, flying from New York to Los Angeles and back on a single battery charge. Or, picture using your digital camera or mobile phone for days on end without recharging. QuantumSphere has just filed a patent for a nanotechnology that extends the capacity of lithium-ion (Li-ion) batteries up to five times. “We’re working on the anode side of the battery and will then begin work on the cathode side soon, with the production...

Getting high output power and excellent linearity in a millimeter-wave amplifier is no easy trick. But Avago has done it with its AMMC/P-6333 (see the figure). This high-performance driver amplifier offers high gain and power with excellent input and output return losses. It also targets the need for broadband and eliminates the need for a negative voltage. Primary...

International Rectifier Corp. has successfully developed a GaN-based (gallium-nitride) power-device technology platform. It’s expected to provide improvements in two key application-specific figures of merit, on resistance and gate charge, of up to a factor of 10 compared to state-of-the-art silicon-based technology platforms. On resistance relates to how much current you can process in a unit area. It also can be related to the cost per amp of...

One of the most popular sections of Electronic Design in both print and on the Web over the years has been Ideas for Design (IFDs). We’d like to celebrate this department by dedicating this entire issue to IFDs, including insightful commentary from our editors and contributors alike. First, we’ve asked some of the industry’s top engineers, who we like to call design gurus, to reflect and write about the circuits they’ve created over the ...

VOLTAGE REFERENCES GENERATE WIDEBAND noise spectrums. For most semiconductor devices, this spectrum usually has a wideband “white noise” component with relatively constant power density versus frequency, and a “pink noise” or “1/f noise” component that grows with the inverse of frequency.1,2 The pink noise component rises up from the relatively flat white noise level at a point somewhere between a few hundred hertz and a kilohertz, and it increases 3 dB ...

Solar-power researchers at the Massachusetts Institute of Technology (MIT) have been very busy in their labs lately, and not without significant fruits for their labors. Two projects promise to elevate solar power from an expensive and cumbersome alternative to an affordable and unlimited energy source. SOLAR POWER GOES GREEN-LITERALLY! Relying on the process of photosynthesis occurring in plants for inspiration, MIT...

Power designers often prefer particular power products or manufacturers. Some designers try to drive these preferences into every application. That’s not surprising. Such choices are usually based on successful relationships with specific manufacturers. The designers already know the products, or they can rely on a level of reliability, on-time delivery, or good prices. Many suppliers of dc-dc converters offer common input and output voltages, power levels, and features....

Ceramic capacitors are rapidly increasing in capacitance and volumetric efficiency (CV/cc) due to higher dielectric constants and smaller dielectric thickness as well as higher layer counts. To compete with ceramic capacitors and meet demands for miniaturization, tantalum (Ta) capacitors also need to increase their volumetric efficiency. Traditionally, the only way to increase CV/cc in Ta capacitors was to reduce particle size in the Ta powder, thereby...

With the mass proliferation of mobile devices and various computer and homeentertainment peripherals, most of us suffer from a bad case of wall warts. Doug Palmer, a principal development engineer at the San Diego division of the California Institute for Telecommunications and Information Technology (Calit2), uses the phrase “wall warts” to describe the plethora of external power supplies that vie for position in his and our wall sockets and power strips...

As digital-camera and phone-camera resolution increases, high-resolution image sensors require more light. Firstgeneration low-res camera phones provided barely adequate flash intensity for taking closeups of friends at parties. Even second-generation camera-phone flash is still unsuitable for image sensors with greater than 3-Mpixel resolution. And that’s just talking about still photography. Video requires in-phone camera lighting to provide...

The mobile version of the WiMAX broadband wireless technology is beginning to roll out as laptop manufacturers add it to their PCs and as other companies make wireless access points for the home and office. Now, all of these designers have access to a WiMAX power amplifier (PA) thanks to SiGe Semiconductor. The SE7262L is a 2.5-GHz PA for batterypowered devices. It delivers 28.5 dBm of output power (708 mW) with an efficiency of 20%—not bad...

A few engineers were having a debate. According to all the books, some of them said, op amps are supposed to have zero output impedance, or very low. That means the output voltage wonâ??t change, just in case the output current changes. Some older op amps had an output impedance of 600 ? or 50 ?. So, the gain of the amplifier wonâ??t change just because the load changes. That must be good. But a couple of other engineers pointed out that many modern op...

• Build A Smart Battery Charger Using A Single-Transistor Circuit
• Efficient DC-To-AC Inverters Charge Equipment Racks
• DC-AC inverter targets electroluminescent applications
• Easy-To-Build AC Power Meter
• Low-Dropout (LDO) Linear Regulators