| Summary: | 碩士 === 國立交通大學 === 電機學院IC設計產業專班 === 96 === Due to low-amplitude and non-stationary properties of biomedical signals, high resolution and low-power consumption are necessary for the analog-to-digital (A/D) convector. Based on the above reason, the sigma-delta modulator (SDM) which has well performance in the resolution and power consumption is chosen. To deal with different biomedical signals and offering different resolution, this thesis proposes a reconfigurable sigma-delta modulator. The advantage of design is to use three built-in modulators to implement hardware reconfiguration and to achieve transformation of high resolution via digital switching control. Compared with the traditional method, the proposed design has higher efficiency and saves chip area. There are two kinds of operating modes. One is two first-order SDMs used to low resolution. The other is the second-order SDM which is reconfigured by two first-order SDMs, and it is suitable for higher resolution.
The proposed sigma-delta modulator fabricated in TSMC 0.35um 2P 4M CMOS technology consumes 3 mW at 256 KHz. The SNR of the first-order and the second-order modulator can reach 66 dB and 86 dB, respectively, within 1 kHz of signal bandwidth and 128 times sampling rate. The resolutions are 10 bits and 14 bits with the respective to the first-order and the second-order modulator. Most importantly, the core area of the proposed one can be saved around 30% compared with area of two first-order and one second-order sigma-delta modulators without reconfigurability.
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