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| Effect of Intermodulation on Bridge Balance and the Development of the Method for Its Restraint |
| LIU Jian-bo1,2,CHI Zong-tao1,ZHAO Jian-ting2,LU Yun-feng2,HE Qing2 |
1. Qingdao University, Qingdao, Shandong 266071, China
2. National Institute of Metrology, Beijing 100013, China |
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Abstract A detailed discussion is given of the effects of intermodulation caused by the nonlinearity in bridge null detector system. A resonant filter circuit with high Q value was designed and fabricated to restrain this effect. The required large inductances for the harmonic filter are realized by a winding on high-permeability porcelain jar cores,the highest Q value and lowest losses noise can be obtained by adjusting the gap of two porcelain jar. Experiment results shows that the input noise of the filter is less than 1nV/Hz, and the error caused by intermodulation distortion effect was reduced efficiently by more than two orders of magnitude.
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2011, Vol. 32 
