Can digital pressure sensors get you ahead of the game?
We live in an analogue world. To give the electronic systems we design the ability to detect changes to what is around them we need analogue sensors. But the processing that sits behind those sensors is in almost every case going to be in the digital domain.
Although there are some processing techniques that may be more energy efficient in the analogue domain, conversion to digital provides the greatest flexibility and opens up the true potential of the IoT.
It is not just the conversion to digital numbers that unlocks the power of the IoT; it is the ability to tag those values with additional metadata. The value of a pressure sensor, for example, is only useful if we know when and where that reading was taken so we can correlate it with information from other sensors. By working with the data in combination with the metadata we can gain a better understanding of what is happening around us and then take action. For example, pressure sensors are now being incorporated into smartphones. One of the applications is to use changes in environmental air pressure to confirm the position of the device in the world.
There are multiple markets that need to collect, interpret, process and deliver digitised data from the real world. Connected home appliances can combine information on air pressure with temperature and other environmental signals to optimise the pumping action of heating and air-conditioning systems. In the industrial environment, time-series pressure data can reveal important information about the operation of the system. For example, in oil drilling the changes in pressure over time can reveal leaks and other problems. The information the sensors provide can be used by remote servers to update preventive maintenance applications, which are increasingly making use of machine-learning techniques to identify problems before they become critical. The ability to provide both data and metadata, such as the time and pump conditions during each reading, is vital to ensure each of the target systems understands the proper context.
There are other more subtle advantages to digitising data. Through Moore’s Law scaling, we have seen the energy required per calculation fall year on year. And we can look forward to another decade’s worth of digital scaling at least. We can also take advantage of improvements in circuit innovation and digital design to reduce the voltages at which the processing takes place. As power consumption has a quadratic relationship to supply voltage, every fraction of a volt our circuits are able to shave off leads to a much greater benefit in energy saved.
The question then is where does the analogue-to-digital conversion take place? Traditionally, it has been the job of the system designer to take an analogue-output sensor and add the various signal-conditioning, amplification and conversion components to their board design. This provides them with the flexibility to match...