Smart metering technology is being implemented in an effort to be more energy efficient. Traditional electromechanical meters operate by counting the revolutions of a metal disc, which rotates at a speed proportional to the power passing through the meter. The number of revolutions is proportional to the energy usage. Smart meters, however, are able to remotely communicate directly with the energy supplier, enabling the company to have an accurate meter reading. Advanced metering infrastructure (AMI) is an integrated system of smart meters, communications networks, and data management systems that enables two-way communication between utilities and customers. Utility companies and energy regulators are looking to leverage this technology to improve energy conservation by implementing the Smart Grid, which is a newer and more efficient version of the current electric grid system. A Smart Grid  gathers information in an automated fashion about the behavior of suppliers and consumers in order to improve the efficiency, reliability, economics, and sustainability of the production and distribution of electricity. AMI and Smart Grid technology are both seen as important technologies to improve energy efficiency.

Power Amplifier Technology Targets Efficiency, Fig. 2

RF Micro Devices, Inc. (RFMD) is committed to developing products for smart energy/AMI applications. The company recently unveiled the RFFM6403 (Fig. 2) highly integrated front-end module (FEM), which is intended for use in smart energy/AMI applications. The RFFM6403, which operates in the 405 to 475 MHz frequency range, is designed for AMI systems with high efficiency requirements.

RF Energy Harvesting

Ambient RF energy is everywhere in today's wireless world, and is available from sources such as mobile telephones, handheld radios, mobile base stations, and television broadcast stations. Energy harvesting technology is enabling low-power devices to be charged wirelessly by capturing ambient RF energy from these sources. This harvested RF energy can be converted and stored for use in other applications. Harvested RF energy, which is basically free energy, can eliminate battery replacement or extend the operating life of systems using disposable batteries. A power-generating circuit, which is linked to a receiving antenna, is used to convert RF energy into usable DC voltage. The converted power can be stored directly in a battery or accumulated in a capacitor. Although the power available from ambient RF energy is very low, it has proven to be sufficient for applications such as RF identification (RFID) tags, wireless sensor networks, and more recently, smartphones. The markets for wireless charging by means of RF energy harvesting are only expected to grow.

Powercast Corp. is recognized as one of the leading vendors of RF power harvesting technology. The company develops wireless power and RF energy harvesting solutions to provide power-over-distance transfers for low-power applications. Powercast's patented technology enables devices that typically operate on batteries to benefit from high-efficiency RF energy harvesting technology. The company's Powerharvester receivers (Fig. 3) are designed into low-power wireless products, as embedded wireless power sources that deliver renewable energy by converting radio waves to DC power, which can be stored directly in a battery for short-range applications. Powercast has partnered with a number of electronic-products providers to deliver comprehensive development kits. Powercast and Microchip Technology, Inc. have partnered to provide the Lifetime Power Energy Harvesting development kit, which is based on Microchip's low-power microcontrollers and Powercast's Powerharvester receivers. This complete development kit enables remote electronics, such as sensors and input devices, to be wirelessly powered from RF/microwave power sources at distances as far as 40 feet.

Power Amplifier Technology Targets Efficiency, Fig. 3NXP is also introducing a portfolio of RF power transistors designed to enable RF energy to be used as a clean and highly efficient power source. The company is offering the BLF2425M and BLF25M series of RF power transistors, which are optimally matched to the 2.45-GHz industrial, scientific, and medical (ISM) band. This transistor portfolio was developed with the intention of using RF-powered solutions for home appliances, medical devices, and automotive engines. The potential energy savings that could be realized using RF power are very large.