| Summary: | 碩士 === 國立交通大學 === 電控工程研究所 === 106 === The main measurement and positioning apparatus, according to the sensor type of encoder, besides the laser interferometer that is more high precision displacement measurement system, can be classified into two types, the optical and magnetic encoder. The encoder always employs sensor passing through periodic and equal distance grating and then generates periodic quadrature scaling signals for displacement measurement. The phase is relative to the movement. To improve encoder accuracy or resolution, electronic interpolation technique had been developed to subdivide the phase of quadrature scaling signals.
According to the trends, this thesis proposed a specific LUT with great noise immunity characteristic and a complete calibration process to improve the accuracy of system. And this chip was realized and involved 1024 and 2048 two different folds interpolation circuit. First, front-end circuits would adjust the sensor voltage. And the modulator of 14-bit Delta Sigma DAC dose the oversampling analysis. Next, do the decimation for dropping frequency by the decimator and output a digital signal. The digital signal would be adjusted by the calibration circuit. Last, system can obtain a high precision position and displacement with mathematical model and algorithm. This interpolation method satisfy the requirement of modern semiconductor and precision industry. The designed circuit has been successfully fabricated by using TSMC 0.18-μm CMOS process, where the active area is 1491 μm x 1488 μm. The power voltage is about 3.3 V. The clock is about 5.12 MHz. The measured power consumption of chip is about 0.292 mW. The accuracy of measurement system is 0.7 μm.
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