Advancements in the fields of energy harvesting, sensor networks, building automation, and security systems are making tremendous strides due to recent innovations in precision circuit semiconductors. While developers seek integration for all four system categories, the precision semiconductor technology delivers markedly improved system sensitivity, reliability, stability, and functionality. Growth and interest in these systems has evolved to the point where the IEEE is developing protocols for a more integrated approach to sensor networks and building automation so that end solutions are more cost effective and energy efficient.
Industry standards for such systems are called for in a document entitled “Building lighting automation through the integration of DALI with wireless sensor networks.” The consumer electronics-focused Transactions journal published the paper on the integration of Digital Addressable Lighting Interface (DALI) devices in wireless sensor networks and explores possible improvements for the technology.
Since different manufacturers usually deal with one aspect of building automation — for example, heating ventilation and air conditioning, lighting control, different kinds of alarms, etc. — final building automation system has different subsystems that are finally taken to an integrated building management system.
An economical fully centralized system
Our main purpose is to provide the end consumer with an economical fully centralized system in which home appliances are managed by an IEEE 802.15.4-based wireless sensor network.
The case of building automation is ideal for demonstrating how advances in semiconductor technology enable breakthrough capabilities for these systems. Operators of large facilities such as office buildings and municipal complexes have made great strides in cutting cost and improving energy efficiency by using building automation and security in conjunction with energy-harvesting systems and wireless sensor networks.
Large office complexes use sensor networks to interface with building controls to turn on power, heating, and ventilation to individual offices and cubicles only when people are present. However, there is much room for improvement in such systems as anyone who has had their office lights shut off in the middle of the working day might attest. By improving the circuits of these systems, it’s possible to improve accuracy of the controls that activate building automations systems so that they more accurately respond to real-life situations for which they were intended.
In practical applications, the technology hasn’t always worked as designed. Systems set up to detect the presence of motion and temperature changes are limited in their capabilities and this has undesired results. That’s why lights turn off even when workers are present. The systems have limitations in accuracy, reliability, and sensitivity range. The goal of many in sensor network and building automation development is to improve the technology so that it truly matches the real-life situations for which they were designed.
Circuit design progress
One of the most important areas where designers are making progress is in the basic building blocks of circuit design. With better circuits that afford greater operating dynamics, building automation and security systems are finely attuned to real-life usage models. For example, greater sensitivity and reliability can prevent costly false alarms in building security.
Energy harvesting and ultra-low power are also important features that enable greater reliability and cost-effective wireless installation. In building a system, designers desire extremely low power circuits, so that as much energy as possible can be harvested, stored, and used for some other purpose. If the electronics consume a prohibitive amount of power, it is difficult to build high-efficiency systems.
It is important that these circuits consume as little energy as possible so that the current and voltage that is harnessed from an ambient source can be maximized to drive the electronic systems that they were intended to supply. Greater power ranges provide building automation system developers and end-users with greater flexibility and reliability to deploy improved solutions.
Today, energy harvesting is a growing field because it helps building operators with the ability to install automation controls with wireless networks. This helps eliminate cost and complexity for operators who want to improve the efficiency and reduce the operating cost of their facilities.
The research firm IDTechEx expects the total market of energy-harvesting devices to rise to more than $5 billion in 2022. In a report, the firm stated, “The technology has reached a tipping point, because the necessary lower power electronics and more efficient energy gathering and storage are now sufficiently affordable, reliable, and longer-lived for a huge number of applications to be practicable.”
An example of this type of advancement is the ALD210800 MOSFET array, with a gate threshold voltage is exactly 0.00-V ± 0.001 (±10 mV). This new category of device enables breakthrough analog circuit design parameters, such as:
• 100-mV minimum operating voltage
• 1-nA minimum operating current
• 1-nW minimum operating power
The ALD210800 is a basic building block in circuits to enable greater sensor sensitivity. Each MOSFET is enabled by fully independent input and output, source, and drain. Compared to previous generations, it increases current output by greater than an order of magnitude. It also reduces circuit size by 50%, which in turn helps decrease board real estate and cost.
The MOSFET array is designed to tap a number of energy-harvesting sources that have less than a 1-V supply voltage. The array also helps improve energy efficiency and extend battery life. Designed with precise specifications, this new category of device gives developers a new frontier of operating voltages, power consumption, and increased precision. In the analog world, precision is always welcome.
N-channel current source
Figure 1 depicts a circuit design for a very basic current source. Actual useful current and voltage ranges also depend on the device being used. The ALD 210800 offers the highest precision performance with the lowest current and voltage requirements. You can build this current source with any of the devices that are listed above or that are currently on the market. The difference is the actual specifications that can be achieved. This marks a new frontier for basic MOSFET circuits.
Fig. 1: Current-source circuit diagram constructed with precision semiconductor devices
With innovative materials like the new generation of ultra-precise semiconductors, developers of energy-harvesting systems and sensor arrays will be able to make improvements in building automation security, wireless networks, and building automation. Sensors will be given greater dynamic range to detect motion and heat. This will spur greater sensitivity to detect when people are present and when they are not, and afford operators finer granularity in controlling their facilities.
The new category of precision circuit semiconductors will enable the circuits supporting these systems to be more stable more reliable and more dependable. It also allows energy harvesting systems to make greater use of the ambient energy and store power when it is not needed so that systems are ready to be deployed when they are called into action.
About the author
Robert L. Chao, CEO of Advanced Linear Devices in Sunnyvale, CA, founded ALD in 1985 and has been a leading authority in the analog semiconductor industry for over 30 years. A founder of Supertex, Mr. Chao was instrumental in inventing the analog circuitry that enabled the home smoke detector.
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