An iterative least-square based technique for high resolution source reconstruction with phaseless near field scan data

Due to continuous increasing operating frequency and shrinking component scale, considerable attention has been drawn to electromagnetic interference (EMI) and signal integrity (SI) problems in microelectronics. To solve these problems, near field scan (NFS) is adopted to locate radiating sources on devices under test (DUT). During the NFS process, ultra close-to-surface scan is required to enhance the resolution of scanned images due to the evanescing nature of electromagnetic fields. To compensate for the evanescence effect, recently inversion techniques have been employed. Inversion methods consider the radiating model of DUTs and reconstruct radiating sources based on scanned fields. The advantages of inversion methods including more flexibility for scan height and higher resolution on reconstructed images. However, conventional inversion methods require both magnitude and phase information of scanned fields. Obtaining phase information of near fields will dramatically increase the complexity and/or time of a NFS process. One possible way to overcome this problem is to utilize only the magnitude of radiated fields during inversion process. Unfortunately this attempt will result in solving a set of nonlinear equations which significantly increases the computational complexity of this problem.