Do More with Less: Designing With Power-Efficient Data Converters (.PDF Download)
No matter your target application, it’s desirable to make the design as “green” as possible in today’s world. That means meeting the required performance goals with the minimum power consumption.
In data-acquisition design, an analog-to-digital converter (ADC) is available for just about every application. However, there can be considerable overlap, and high performance, low power consumption, and small size are often conflicting goals.
For example, higher-performance converter architectures tend to require more silicon and consume more power, which leads to larger packages. Prioritizing low power consumption and small size may require compromising the performance, perhaps reducing the resolution or sample rate.
The power consumption of the data-acquisition signal chain also depends heavily on two additional factors: the power dissipated by the input driver and the efficiency of the power supply. This can be challenging for systems that require a combination of high performance and low power.
Let’s look at some power-efficient data-acquisition designs targeting three very different applications and performance levels, and examine what steps we can take to reduce power consumption while maintaining performance.
Low-Speed Applications
Many data-acquisition applications don't need blazing speeds because the physical quantities measured by the input sensors change relatively slowly. In this application space, battery-powered designs are common.
Examples of such systems include wearables (fitness bands, smart watches; CO2 detectors, smoke detectors, or smart thermostats in home automation); industrial modules (remote sensors or data loggers; glucose meters, cardiac monitors, and similar portable or implantable medical devices); and security equipment (cameras or motion detectors).
These systems often must run for extended periods—months or even years—on a single battery charge. To minimize power consumption, each electronic component in the design should consume as little power as possible when performing its necessary function and go into a low power state as often as possible. Reducing the power consumption translates into extended battery life and a market advantage.