Study And Design Of Signal Processing ASIC For MEMS Capacitance Sensor

Micro-machined sensors based on the MEMS technology are very important sensors. These sensors can be fabricated together with their interface circuit on the same silicon substrate. As a result, the cost can be lowered while the sensitivity and the resolution can be improved. A capacitive sensor includes a variable capacitor transducer which varies its capacitance according to the environmental parameter. They are widely used in the applications of parameter measurement such as pressure, humidity, temperature and acceleration, etc, comparing with other sensors , the capacitive sensors consume less power, have less temperature coefficient and higher sensitivity. MEMS capacitive sensors are studied actively since they own the advantages of both MEMS sensors and capacitive sensors.With the fast development of the design and manufacturing level of MEMS, the change of the sensor capacitance becomes much smaller along with the sensor capacitor, complicating the design of readout circuit. Since the sensitivity of the sensor highly depends on the readout circuit, we propose a ASIC for multi-dimension accelerator with low noise in this paper.The main work and achievement are as follows:1 Carefully study the working principle of the MEMS capacitive sensors, and determine the equivalent model. Determine the specification of the ASIC by input range and resolution requirements.2 Conduct literature review to determine the topology of this ASIC according to the specification.3 Design the low noise amplifier, timing control circuit, etc. complete the whole device level design.4 Layout of the whole circuit, do DRC/LVS and post-simulation. Extract the GDS file and tape out.5 Thoroughly analyze this circuit to find its drawbacks for further research.