A new high output impedance wideband AC current source with high current swing authority for electrical impedance tomography applications

Abstract

The Electrical impedance tomography (EIT) is a relatively new technical imaging method for industrial applications, medical imaging and relative researches. The most important part of this system is an AC current source. Its characteristics have efficient effects on the performance of EIT systems. The AC current source must have constant current amplitude over the load and frequency ranges in related applications. In this paper, we could by designing a new topology of current source circuit achieving a current source with higher output impedance in comparison with other current sources which are mostly used in EIT applications. In the new designed current source, the output impedance of old current source will be multiplied by limited gain of second op-amp. Also in new topology, the output voltage and current swing are doubled in comparison with modified Howland current source; because, the load impedance seen from the output leg of second op-amp is decreased.