Design and Implementation of a Read-Out Circuit for MEMS Capacitive Accelerometer

 In this project, a Read-Out circuit is designed and implemented to read the capacitive change of an accelerometer designed in the urmia micromachine center. This sensor has a differential structure. Hence, the Read-Out circuit is designed to read the specified accelerometer with required offset cancelation and noise reduction capabilities. This IC is implemented in 0.35um CMOS which gives a 1V/pF electrical scale factor and a dynamic range of about 83dB in the first run. A PTAT circuit is also included for subsequent temperature compensation which works perfectly. The clock is generated internally and the differential output has a swing of 4V peak-to-peak swing.

Accelerometers have versatile applications in today's technology ranging from consumer electronics to space and military applications. Among the important parameters of these sensors are: dynamic range, scale factor, output swing, offset cancelation, and .... To get to the specified requirements, different structures are studied and a simple correlated double-sampling circuit with some modifications is used. The circuit is designed for a specific sensor, and all element values and connections are adopted to gain the specified specifications. The circuit is designed and implemented in 0.35um CMOS technology, the circuit is wholly worked at the first run and almost all specs are achieved.