A Pull-in Operation Mode Accelerometer

In this paper an accelerometer, which measures the pull-in time to obtain the acceleration is presented. As the pull-in time is a semi digital signal, the output of the device can be measured with a full digital circuit. No analogue readout circuit is required. The sensitivity and nonlinearity are comparable with the differential capacitive sensing devices. The accelerometer has been fabricated by surface micromachining using Al as the mechanical layer and phosphosilicate glass as the sacrificial layer. The initial measurements have been performed.