A new FPGA-based Detection Method for Spurious Variations in PCBA Power Distribution Network

Nowadays, increasing demand for High-Performance Systems produces significant growth in usage of Field Programmable Gate Arrays (FPGAs) for different applications thanks to their flexibility and high level of parallelism. Such systems rely on complex multi-layer Printed Circuit Board Assemblies (PCBA)with a few dozens of hidden layers, stacked microvias and high-density interconnects. Along with creating new test challenges, the increasing PCBA complexity elevates the criticality of defects in various subsystems. One of such sub-systems is a Power-Delivery-Network (PDN) with operating margin progressively reduced due to increasingly strict requirements of High-Performance applications. As a consequence, Marginal Defects and process variations in a PDN may create latent problems that will manifest in a particular condition thus compromising the overall system performance and causing malfunctions. In this paper we propose a new FPGA-based non-intrusive method to detect Marginal Defects in a PCBA PDN. The method is based on a monitoring circuit that measures signal delays caused by PDN variations and thus detects relevant anomalies. Additional ad-hoc PDN stress circuits have been developed to validate the measurement technique. Experimental results demonstrating the consistency of the proposed approach are obtained by comparing stress and non-stress scenarios.