A Micro-Resistance Measurement Based Design Approach of Digital Micro-Ohmmeter

This paper presents a novel design solution of digital micro-ohmmeter based on the micro-resistance measurements. Through the system analysis, two key factors which have impacts on the measurement accuracy are identified: constant-current source circuit and A/D converter. Therefore, we suggest a design approach to improve the common constant-current source circuit to obtain enhanced system linearity, stability, precision and robustness and use high resolution A/D converter to ensure converting accurately. The proposed design approach is assessed and demonstrates that the load disturbance can be limited to 0.05%, and the measurement precision could reach 0.2% ranging from 20mΩ to 20Ω and 1.0% below 20mΩ.

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