Design and development of automatic level control for indigenous MRI

A Radio Frequency amplifier (RFA) with fully integrated automatic level control is designed for indigenous Magnetic Resonance Imaging (MRI). Automatic Level Control module for RFA using ARM cortex-M4 controller is presented in this work. Out of various control mechanism, peak detection technique is chosen for this experiment. To regulate RFA output at constant level, ALC loop use controller (TM4C123 Board) which tracks the variation in input voltages by means of detecting peak value of input voltages and comparing this with reference voltage, difference will give error voltage that will be given back to attenuator. Depending upon error voltage generated, input voltage will be attenuated to maintain constant non fluctuating power at output of RFA with given timing constraints. Also to ensure proper functioning of RFA, its different parameter like forward power, reflected power, current etc should be monitor at particular level. To monitor and control these parameters Graphical User Interface (GUI) has been developed using LABVIEW.