This study proposes a front-end readout circuit as an encoder chip for magneto-resistance (MR) linear scales. A typical MR sensor consists of two major parts: one is its base structure, also called the magnetic scale, which is embedded with multiple grid MR electrodes, while another is an “MR reader” stage with magnets inside and moving on the rails of the base. As the stage is in motion, the magnetic interaction between the moving stage and the base causes the variation of the magneto-resistances of the grid electrodes. In this study, a front-end readout IC chip is successfully designed and realized to acquire temporally-varying resistances in electrical signals as the stage is in motions. The acquired signals are in fact sinusoids and co-sinusoids, which are further deciphered by the front-end readout circuit via newly-designed programmable gain amplifiers (PGAs) and analog-to-digital converters (ADCs). The PGA is particularly designed to amplify the signals up to full dynamic ranges and up to 1 MHz. A 12-bit successive approximation register (SAR) ADC for analog-to-digital conversion is designed with linearity performance of ±1 in the least significant bit (LSB) over the input range of 0.5–2.5 V from peak to peak. The chip was fabricated by the Taiwan Semiconductor Manufacturing Company (TSMC) 0.35-micron complementary metal oxide semiconductor (CMOS) technology for verification with a chip size of 6.61 mm2, while the power consumption is 56 mW from a 5-V power supply. The measured integral non-linearity (INL) is −0.79–0.95 LSB while the differential non-linearity (DNL) is −0.68–0.72 LSB. The effective number of bits (ENOB) of the designed ADC is validated as 10.86 for converting the input analog signal to digital counterparts. Experimental validation was conducted. A digital decoder is orchestrated to decipher the harmonic outputs from the ADC via interpolation to the position of the moving stage. It was found that the displacement measurement error is within ±15 µm for a measuring range of 10 mm.
Since the 1990s, Taiwan has promoted the upgrading of industrial structure, and the financial crisis has brought about major economic shocks. After Taiwan became a World Trade Organization (WTO) member in 2002, the total trade volume increased significantly under the trade liberalization economic system. The trade sector has become the main source of Taiwan's economic growth. As energy consumption expands with economic growth, the instability of international energy prices has become an important factor hindering Taiwan's future economic development. Taiwan's energy demand is over 99% dependent on imports, making Taiwan's economic growth and energy consumption really closely related. This study has found that the source of growth has transformed from domestic final demand effect and exports effect to technical coefficients effect and self-sufficiency Coefficients effect. The financial crisis has increased the "self-sufficiency" coefficient effect and the technical coefficient effect, and all other industries except the "agricultural sector" have shown significant growth. On the other hand, the source of energy consumption has changed after the financial crisis. This also confirms that Taiwan's economic growth is closely related to energy consumption, indicating that energy shortage has indeed had an important impact on Taiwan's economic development.
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