Design And Implementation Of Low Power Two-Order Sigma-Delta Modulator Based On MEMS Geophone

Geophones play a role in detecting and receiving seismic wave data in seismic exploration.The working efficiency and the amount of data collected directly affect subsequent data analysis and processing.Unlike the moving coil sensors used in traditional geophones,MEMS geophones use capacitive sensors inside,which have a wider dynamic range.And the MEMS geophone integrates an analog-to-digital conversion module to directly output digital signals,which avoids the loss of analog signals during transmission.The new MEMS geophone can meet the needs of future digital seismic exploration,but its internal analog-to-digital conversion module needs to be powered up,and seismic exploration requires long-term stable work to obtain enough information samples for subsequent Analytical processing,so the low-power MEMS geophone is a research hotspot.This thesis studies the Sigma-Delta modulator in the analog-to-digital converter of MEMS geophone.Including the research and design and debugging of each sub-circuit module inside the Sigma-Delta modulator,and performing circuit-level simulation;the circuit-level debugging simulation is followed by the layout,and the post-simulation of the layout level is completed;The chip of the Sigma-Delta modulator is streamed,and finally the chip-level test is performed after the chip returns.Design each sub-circuit module of the Sigma-Delta modulator,including designing and debugging the bandgap voltage reference,clock generation circuit,amplifier,integrator and one-bit quantizer circuit.A low-power bandgap voltage reference and a first-stage amplifier are designed for low-power requirements.Considering the nonlinear factors of the integrator,a linearity integrator structure is designed.Perform layout drawing of the circuit layout and optimize it in layout layout.After the layout is completed,the final pin is optimized by the DRC,LVS,and PEX tests to optimize the layout PAD;the metal density of the layout is optimized to meet the processing requirements;and the ESD protection module is added in consideration of the chip processing slicing problem.Finally,the film was dropped to the Microelectronics Institute of the Chinese Academy of Sciences,and was submitted to the SMIC manufacturer by the Institute of Microelectronics of the Chinese Academy of Sciences.After the chip returns,the chip-level test is carried out.The chip die is protected by a bit and then packaged on the PCB test board.The external power supply and the input signal filter circuit are used to build the test platform for chip measurement.This design completes the circuit design,layout drawing and final tape chip test of the two-stage Sigma-Delta modulator under the SMIC 0.18 um process and 1.8V power supply voltage.The results show that the designed Sigma-Delta modulator consumes only 3.05 mW.