초록
A inductive voltage divider(IVD) is widely used as a ratio arm of precise impedance measurement bridges at low frequencies of audio frequency range and a well fabricated IVD has ratio error of $10^{-7}$ order without any calibration. Recently, the order of $10^{-8}$ of the best measurement uncertainty is needed for calibration and maintenance of impedance standards as national standards. In order to achieve that uncertainty, the IVD which is used for a ratio arm of precise impedance measurement bridge should be calibrated within the uncertain of order of $10^{-8}$ For this purpose, a ratio calibration bridge for IVDs has been developed. The measurement uncertainties of both inphase and quadrature of the bridge are analyzed less then $3{\times}10^{-8}$ respectively at 1 kHz and 25 V.
