A Programmable Current Source for MRCDI & MREIT Applications

In this study, a four-channel programmable current source, to be used in magnetic resonance current density imaging (MRCDI) and magnetic resonance electrical impedance tomography (MREIT) applications, is designed and implemented. The current source is composed of a microcontroller unit, a digital to analog convertor, a step-up DC-DC convertor, and a voltage to current (V-I) convertor with a current steering topology. TFT-LCD screen in the microcontroller unit provides a user-friendly graphical user interface (GUI), in which the amplitude, pulse-width, and application time of the output current can be adjusted for each channel. The step-up DC-DC convertor is used to satisfy the high voltage requirement of the current source. It operates with a feedback taken from V-I convertor in order to prevent excess-power consumption during the low level output current injection. The programmed output current is injected to the load by the V-I convertor with a current steering topology. The amplitude and temporal resolution of the output current are significantly high.