High-linearity fully differential digital micro-accelerometer interface circuit system

Abstract

The invention belongs to the field of MEMS (Micro-Electro-Mechanical Systems) inertia devices, and particularly relates to a capacitance type micro-accelerometer digital output fully differential digital micro-accelerometer interface circuit system. The system comprises a drive signal generating part, a fully differential charge integrator, a fully differential post-amplifier, a fully differential pre-distorter, a relative dual-sampling and sampling retaining circuit, a fully electric integrator, a dynamic comparator, a D / A (Digital / Audio) converter and an electrostatic force feedback device. The system improves the linearity of an accelerometer system, effectively lowers the quantization noise of D / A conversion, restrains zero shift, reduces common mode interference generated by switching charge injection and a substrate noise, improves power supply rejection ration (PSRR), and reduces harmonic distortion.

Description

technical field [0001] The invention belongs to the field of MEMS inertial devices, and in particular relates to a fully differential digital accelerometer interface circuit system with digital output of a capacitive micro accelerometer. Background technique [0002] MEMS (Micro Electromechanical System) is developed on the basis of microelectronics technology. Devices made with MEMS technology are widely used in aerospace due to their advantages of miniaturization, intelligence, integration, and high reliability. , automobiles, biomedicine, environmental monitoring and almost all fields that people come into contact with. Micromachined accelerometers are one of the most important MEMS devices, second only to pressure sensors in terms of market sales. Micro-accelerometers have the advantages of small size, low power consumption, good stability, high reliability, and convenience for mass production, and are widely used in the automotive industry, aerospace fields, and consum...

AI Technical Summary

Problems solved by technology

[0005] However, for the fully differential ΣΔ signal processing structure, there is a main problem: in the differential structure, the driving signal is applied to the active electrode, so the feedback voltage can only be applied to the fixed electrode. When feedback, the active electrode is grounded, and the two fixed electrodes One of the boards is connected to the feedback voltage V fb , and the other is also connected to 0 potential to form an electrostatic force opposite to the inertial force. The resultant electrostatic force on the active electrode and the feedback voltage have a quadratic relationship, which reduces the linearity of the system.

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