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Learning Lessons in Power and Portability

Power and portability for important concerns for electronic devices on the battlefield, just as they are in the consumer space.

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Power and portability often go together for an electronic device, especially when it comes equipped with a fully charged battery. But when the power runs out, it doesn’t matter how small or otherwise portable an electronic device might be, since it won’t be of much use. Batteries and power cells can be made to last longer, with increased capacities for greater portability. But this usually means larger batteries with an increase in size and weight—and a corresponding sacrifice in portability for the increase in power.

As in civilian life, the battlefield has been experiencing a growing reliance on electronic devices. Many of the portable electronic devices are tools meant to support a soldier, such as a two-way radio, a back-pack computer, or a GPS receiver for positioning and guidance. Some may be more elaborate electronic devices, such as signal activity receivers that detect and display RF/microwave signal activity with a certain frequency range and transmission distance.

However, in a growing number of cases, portable electronic technology is needed for “things,” such as the portable radars or surveillance systems that are installed in unmanned ground vehicles (UGVs) or unmanned aerial vehicles (UAVs). The effectiveness of a surveillance system on a UAV depends on running time, with the security and covertness of a particular mission often relying on having enough time in the field to gather meaningful data without being observed.

Whether for a soldier or a UAV, achieving longer running times with portable electronic devices is not simply a matter of using a larger battery, since the added weight can slow down both the soldier and the thing. In the commercial world, device and circuit designers faced with the growing number of Internet of Things (IoT) applications are learning how to develop more efficient electronic solutions that can operate with less current draw and at lower voltages. In doing so, there is no need to reach for a larger battery to gain longer running times.

In many portable tactical applications involving transmission and reception of RF/microwave signals, the power amplifier is one of the main culprits when it comes to power consumption. Amplifier designers have seen something of a parade of different semiconductor devices over the last few decades, from silicon bipolar transistors and GaAs MESFETs through the current generation of GaN device.

Some applications must balance signal linearity with efficiency, so that saving power becomes a challenge. A number of different amplifier architectures enable high efficiency, but amplifier efficiency also starts at the device stage. The development of new, lower-power-consumption active devices for portable electronics—whether for commercial or military use—will depend a great deal on learning from active device models and software simulation tools.

Power consumption in portable electronic devices is not just about the amplifier, of course, and the growing amount of digital content in battlefield electronics also requires taking an approach of designing for efficiency. The use of nanostructures an small-dimensioned digital circuits can help achieve some of the data conversion and signal processing functions needed from digital circuits without adding significantly to the power budget.

Electronic devices have become mainstays of both commercial and military life, and portability is often a key aspect of those devices. To ensure portability as functionality increases, power efficiency must be one of the main design requirements and not just a side-benefit or afterthought. Defense designers have learned how to scavenge and reuse power, from sunlight, wind, other RF sources. Nevertheless, designing for efficiency will help set the threshold for the amount of power needed for a device, and for how long it can be truly portable.

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