| As silicon based sensor technology continues to experience accelerating growth, there exists an obvious trend toward combining MEMS transducers with increasingly sophisticated circuits. In those integrated sensing systems, on-chip circuits can perform such operations as amplification, calibration, averaging and data translation of sensor output, greatly enhancing the overall integrity and modularity of the system output.; The goal of this work is to develop a single chip polysilicon strain sensing system with digital readout and on-chip self-test and self-calibration for structural health and usage monitoring. Polysilicon cantilever beam off surface strain sensor and polysilicon membrane type strain sensor fabricated by MEMS technology have been investigated. A low power CMOS sensor interface was developed based on experimental results.; In the sensor interface design, we implemented noise-immune digital readout of sensor output by 10-bit resolution 1Msample/sec successive approximation analog to digital converter. Because the sensor array consumed considerable chip area, an area-efficient successive approximation register was implemented with minimum flip-flops. To further minimize the chip area and power consumption, voltage-division segmented R-2R ladder digital to analog converter was designed as DAC core, which was fabricated in single poly, twin-well, CMOS process.; On-chip sensor self-test was developed for safety critical applications based on the built-in redundancy of strain sensor array and successive approximation measurement technique. A novel hardware implementation was developed to meet the random successive approximation requirements based on programmable DAC output. To improve the quality of digital subsystem concurrent error detection, we developed a noninvasive built-in current sensor for IDDQ testing based on Hall effect for I/V conversion.; Experimental results were presented and discussed, which compared favorably to other reported designs. |
PDF Full Text Request