Signal Gain
Relationship between a physical displacement and the resulting change in electrical potential defines the transducer efficiency. Capacitive sense gain determines how many volts are produced per unit of capacitance change in a micro-machined sensor. Transducer factor dictates the minimum detectable signal for the entire system.
Scaling Accuracy
Precise calibration of the amplifier circuit ensures that the output voltage accurately represents the movement of the proof mass. High gain settings increase sensitivity but also amplify the electronic noise floor of the front-end electronics. Choosing the optimal balance depends on the dynamic range requirements of the application.
Noise Impact
Thermal noise from the feedback resistor and the input stage of the amplifier limits the resolution of the measurement. As capacitive sense gain increases, the signal-to-noise ratio must remain high enough to distinguish real motion from random fluctuations. Shielding the sense traces prevents external electromagnetic interference from degrading the output quality.
Temperature Sensitivity
Variations in ambient temperature alter the dielectric constant of the gap and the mechanical properties of the electrodes. These changes shift the gain over time, necessitating the use of internal compensation algorithms or stable reference capacitors. A drift of several parts per million can lead to measurement errors if the system is not properly characterized across the full operating range.
Performance verification usually occurs at the package level before the sensor is integrated into a larger assembly. Characterization curves are used to program the temperature compensation registers in the digital controller.
