The simulation of current generator design for multi-frequency electrical impedance tomograph.

In the development of new generation EIT systems, the design of a steady current generator with broad bandwidth is an important consideration. In this paper, the current generator is constructed by enhanced Howland circuit with high-speed operational amplifier. The electronic models of current generator built on Orcad PSpice 9.2 software are simulated to observe the output current stability at multi-frequencies. As results, the THS4021 model provides stable output current at the frequency ranging from 10 k to 1 MHz with the load for 200-2 kOmega. Furthermore, it also offers higher output impedance that equal to 2.1 MOmega at 1 MHz. The results of simulations provide useful approaches of current generator design for EIT system.