Taking the Strain: Integrating precision strain gage measurements into a programmable SoC

摘要

Many pressure and force sensors rely on resistive sensing elements connected in some variant of the so-called bridge configuration. In the electrical context, a 'bridge' is a common topology in which four two-terminal devices are connected in a loop. Think of the ubiquitous 'bridge rectifier' - if you are reading this article, chances are that you have used one of those in a power supply design. When the two-terminal devices are impedances whose values can be changed by some external influence, you get an incredibly versatile sub-circuit. If you mix impedances with difference frequency behaviors, you can create interesting filter and oscillator circuits- you've probably heard of the Wien Bridge oscillator , which relies on the frequency-dependent transfer properties of Figure 1.