ELECTRONICS.CA PUBLICATIONS announces the availability of a comprehensive global report on Surface Mount Technology (SMT) Equipment. The global market for Surface Mount Technology Equipment is projected to reach US$4.5 billion by 2020, driven by the strong demand for electronic products and the ensuing increase in production of Printed Circuit Boards (PCBs).
Circuit that reduces power leakage when transmitters are idle could greatly extend battery life
At this year’s Consumer Electronics Show in Las Vegas, the big theme was the “Internet of things” — the idea that everything in the human environment, from kitchen appliances to industrial equipment, could be equipped with sensors and processors that can exchange data, helping with maintenance and the coordination of tasks.
Realizing that vision, however, requires transmitters that are powerful enough to broadcast to devices dozens of yards away but energy-efficient enough to last for months — or even to harvest energy from heat or mechanical vibrations.
“A key challenge is designing these circuits with extremely low standby power, because most of these devices are just sitting idling, waiting for some event to trigger a communication,” explains Anantha Chandrakasan, the Joseph F. and Nancy P. Keithley Professor in Electrical Engineering at MIT. “When it’s on, you want to be as efficient as possible, and when it’s off, you want to really cut off the off-state power, the leakage power.”
This week, at the Institute of Electrical and Electronics Engineers’ International Solid-State Circuits Conference, Chandrakasan’s group will present a new transmitter design that reduces off-state leakage 100-fold. At the same time, it provides adequate power for Bluetooth transmission, or for the even longer-range 802.15.4 wireless-communication protocol.
“The trick is that we borrow techniques that we use to reduce the leakage power in digital circuits,” Chandrakasan explains. The basic element of a digital circuit is a transistor, in which two electrical leads are connected by a semiconducting material, such as silicon. In their native states, semiconductors are not particularly good conductors. But in a transistor, the semiconductor has a second wire sitting on top of it, which runs perpendicularly to the electrical leads. Sending a positive charge through this wire — known as the gate — draws electrons toward it. The concentration of electrons creates a bridge that current can cross between the leads.
But while semiconductors are not naturally very good conductors, neither are they perfect insulators. Even when no charge is applied to the gate, some current still leaks across the transistor. It’s not much, but over time, it can make a big difference in the battery life of a device that spends most of its time sitting idle.
Chandrakasan — along with Arun Paidimarri, an MIT graduate student in electrical engineering and computer science and first author on the paper, and Nathan Ickes, a research scientist in Chandrakasan’s lab — reduces the leakage by applying a negative charge to the gate when the transmitter is idle. That drives electrons away from the electrical leads, making the semiconductor a much better insulator.
Of course, that strategy works only if generating the negative charge consumes less energy than the circuit would otherwise lose to leakage. In tests conducted on a prototype chip fabricated through the Taiwan Semiconductor Manufacturing Company’s research program, the MIT researchers found that their circuit spent only 20 picowatts of power to save 10,000 picowatts in leakage.
To generate the negative charge efficiently, the MIT researchers use a circuit known as a charge pump, which is a small network of capacitors — electronic components that can store charge — and switches. When the charge pump is exposed to the voltage that drives the chip, charge builds up in one of the capacitors. Throwing one of the switches connects the positive end of the capacitor to the ground, causing a current to flow out the other end. This process is repeated over and over. The only real power drain comes from throwing the switch, which happens about 15 times a second.
To make the transmitter more efficient when it’s active, the researchers adopted techniques that have long been a feature of work in Chandrakasan’s group. Ordinarily, the frequency at which a transmitter can broadcast is a function of its voltage. But the MIT researchers decomposed the problem of generating an electromagnetic signal into discrete steps, only some of which require higher voltages. For those steps, the circuit uses capacitors and inductors to increase voltage locally. That keeps the overall voltage of the circuit down, while still enabling high-frequency transmissions.
What those efficiencies mean for battery life depends on how frequently the transmitter is operational. But if it can get away with broadcasting only every hour or so, the researchers’ circuit can reduce power consumption 100-fold.
This research was funded by Shell and Texas Instruments.
Written by Larry Hardesty, MIT News Office
Experiments at SLAC Show Potential for Graphene-based Organic Electronic Devices
Two leading standards for the electronics assembly industry have been revised. IPC J-STD-001F, Requirements for Soldered Electrical and Electronic Assemblies is recognized worldwide as the sole industry-consensus standard for soldering processes and materials. IPC-A-610F, Acceptability of Electronic Assemblies, is a post-assembly acceptance standard used to ensure electronics assemblies meet the most current acceptance requirements.
Some significant changes to IPC-J-STD-001F and IPC-A-610F standards include:
- Requirements added for two new SMT terminations
- P-Style terminations
- Butt/I terminations — Solder charged terminations
- Revised Class 2 plated-through hole vertical solder fill requirements
- Revised void criteria for BGA/CSP components
- Revised class 2 flux activity criteria
- Improved language for ease of readability and understanding
- Revised soldering requirements for plastic SMT components
- Expanded conformal coating section
- New photos added for clarity
- Simplified Imperial English dimensions utilized in the documents
- Explicit to IPC J-STD-001, revised appendices including guidelines for soldering tools and equipment and objective evidence on material compatibility
The changes listed above are only some of the highlights of J-STD-001F and IPC-A-610F. In order to stay current with best practices in the electronics assemblies industry you need the most current standards, J-STD-001F and IPC-A-610F.
Updated forecast expects robust 8.2% average annual semiconductor unit shipment growth through 2019.
Total semiconductor unit shipments (integrated circuits and opto-sensor-discrete, or O-S-D, devices) are forecast to continue their upward march through the current cyclical period and top one trillion units for the first time in 2017 according to IC Insights forecast presented in the 2015 edition of The McClean Report – A Complete Analysis and Forecast of the Integrated Circuit Industry. Semiconductor shipments in excess of one trillion units are forecast to be the new normal beginning in 2017. Read More