Experiences With a Two-Terminal-Pair Digital Impedance Bridge

This paper describes the realization of a two terminal-pair digital impedance bridge and the test measurements performed with it. The bridge, with a very simple architecture, is based on a commercial two-channel digital signal synthesizer and a synchronous detector. The bridge can perform comparisons between impedances having arbitrary phase and magnitude ratio: its balance is achieved automatically in less than a minute. R-C comparisons with calibrated standards, at kHz frequency and 100 k magnitude level, give ratio errors of the order of 10 6 , with potential for further improvements.