Monolithic CMOS Readout Circuit Design For A MEMS-Based Electrostatic Field Sensor

Readout circuit design for MEMS-Based sensors combines knowledge both insensor and microelectronics. This thesis focuses on the output signal of theMEMS-Based Electrostatic Field Sensor and gives a in-depth research into its readoutcircuit design, setting a bridge for the sensor and the digital world and paving the wayfor the integrated design of the sensor and the following microelectronics circuit.The output signal characteristic of the MEMS-Based Electrostatic Field Sensor isfirstly analyzed. According to the working principle of the sensor, mathematicalmodel and equivalent circuit are established for each excitation mode (single-endedexcitation and double-ended excitation). which should provide guidance to design ofthe the following signal detection circuit.Some new ways of current to voltage converter are presented, either using thelong channel MOSFET working in linear region or the output resistance of transistorsthemselves. A new digitalized peak detector is suggested. This peak detector focusesonly on the peak point of the sine wave signal, simplifying the sample-and-holdrequirement. Taking advantage of voltage to time conversion (or voltage to duty cycleconversion), the resolution is determined by the input clock frequency and thereforecould be very high. Combined with integrated digital circuit, it could output ten bitdigital signal.The above designed circuits are taped-out in Chartered 0.35um CMOS process.The fabricated chips are tested.