Motion-Measuring Circuit for a Vibratory Capacitive Sensor

The figure illustrates an improved electronic circuit that generates a signal proportional to either the instantaneous vibrational velocity or the instantaneous position (equivalently, the instantaneous vibrational displacement) of a vibratory capacitive sensor of the type discussed in the three preceding articles. This circuit offers some advantages over circuits designed previously for the same purpose; in particular, there is no need for a reference capacitor, and the circuit is insensitive to capacitive loading of its sensing amplifier.