Differential and common mode offset correction in read out circuits for open loop half bridge capacitive MEMS accelerometers: Theoretical survey

Capacitive sensors are applied for measurement of a wide range of physical parameters like Position, displacement, vibration, humidity, and acceleration. In Micro electromechanical systems (MEMS) based sensors, the physical parameter to be measured displaces the suspended proof mass between static frames. This displacement alters the distance between the plates or overlap area between plates. The change in capacitance between suspended proof mass and static frames will be proportional to physical parameter to be measured. In some cases, the physical quantity to be measured alters the dielectric property of the material and the physical quantity is measured by measuring the change in capacitance. In the ideal case, capacitive sensors do not consume of generate electrical energy, which makes them practically noise-free. MEMS sensors suffer from production mismatches. Mismatches significantly reduce the dynamic range of the measurement especially in high sensitive capacitance measurements. So techniques to compensate these mismatch errors are explored by various research work. This paper presents the basics of the capacitance measurement using Read out integrated circuits (ROIC), problems with capacitance mismatch errors, various methods and topologies of mismatch correction and compensation in ROIC.