Magnetic Current Imaging with Magnetic Tunnel Junction Sensors—Case Study and Analysis

We describe the use of magnetic tunnel junction (MTJ) sensors for the purposes of magnetic current imaging. First, a case study shows how magnetic and current density images generated using an MTJ sensor probe were used to isolate the root cause of failure in a newly-designed ASIC. We then give a brief introduction to the operation and construction of MTJ sensors. Finally, a full comparison is made between the three types of sensors which have been used for magnetic current imaging: giant magnetoresistive (GMR) sensors, superconducting quantum interference devices (SQUIDs), and magnetic tunnel junctions. These three technologies are quantitatively compared on the basis of spatial resolution, sensitivity, and geometry.