Design of an analog CMOS interface for resonant microsensors

Abstract

The aim of this thesis is to design a CMOS analog integrated circuit for conditioning a MEMS sensor frequency signal of up to 100 kHz, with an amplitude up to 1 μVP . The circuit is designed with the CMOS AMS® 0.35 μm technology process parameters. In order to facilitate the design process, a modular methodology is used. The design starts with the requirements of the complete system, such as gain, bandwidth, power dissipation, etc., and follows with the schematic design of each individual stage. The amplifier design is based on the synthesis of an OTA device which meets signal specifications of typical MEMS transducers for both, frequency and level voltage inputs, which are around 50 kHz, and 10 μVP, respectively. Analytical and simulation results show differences of less than 10 % in the instrumentation amplifier gain, less than 5 % in the gain bandwidth approximation, and less than 7 % in the slew rate parameter for the instrumentation amplifier and the associated devices of the frequency signal conditioning circuit designed for MEMS resonant sensors. The simulation analysis of all stages is performed in both, individual fashion and also in integrated form to verify the complete system operation of the frequency conditioning monitor circuit. Finally, this thesis develops the layout of the circuit, following the same modular methodology, and obtaining reusable modules of the synthesized CMOS stages.