A Four Terminal Pair Digitally Assisted Impedance Bridge at TÜBİTAK UME

Capacitance and AC resistance comparisons at audio frequencies are being performed by using a four-terminal pair transformer-based coaxial AC bridge at TÜBİTAK UME. A four-terminal pair digitally assisted (DA) coaxial AC bridge has been developed in order to reduce the complexity of coaxial transformer AC bridges. This paper describes realization of four-terminal pair DA coaxial AC bridge using commercial DAQ modules and performance test measurements by using the transformer-based bridge. According to preliminary results, the bridge can be balanced automatically in less than 5 minutes. R-R and C-C comparisons at 1 kHz and 10 kΩ magnitude level give ratio errors of a few 10^-6. Further improvements for ratio errors and bridge balancing time will be performed.