Design Of The Closed-loop Detection Circuit For MEMS Accelerometer

Precision MEMS accelerometer systems are highly desired components for a wide range of present-day military and civil applications including the automotive, industrial, consumer, satellite,rocket and missile systems for realizing real time tracking of position. A stable and low-noise interface electronics with high sensitivit- y is highly desirable component for precision inertial sensors.What we have done in this paper are as follows:First, we have a bief review of the development of MEMS technology, MEMS capacitive accelerometer and the CMOS interface circuit.This is helpful for us to make some useful change for interface circuit, in order to meet the requirements of the MEMS capacitive accelerometer closed-loop detection system.Sencond, after having a detail analysis of the two different MEMS capacitive accelerometer and 4 types of weak-signal detection ciucuit, we discussed the advantages and disadvantages between open-loop detection and closed-loop dection.Finally, we determined to choose Capacitive interface circuit and closed-loop detection as the actual program of this project.Third, according to the requirements of the sysytem, we disgned the closed-loop detection system for MEMS capacitive accelerometer. This system contains lots of circuit module, such as pre-amplifier, filter circuit, the ratio amplifier, bandgap reference, the clock oscillator and digital control circuit. With the help of Cadence simulation software, we simulated each of these circuit modules and the system. The reasults indicated that this interface ciucuit could meet the performance of the system.Then, we analyzed the noise mechanism of the MEMS capacitive accelerometer and CMOS interface circuits, as well as methords for the noise suppresion and elimination.At last, based on the MC3010 CMOS process of CETC 24, we designed the whole layout of the cirtuts, and passed through DRC and LVS examination.