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52 DESIGN007 MAGAZINE I JULY 2022 Feature Article by Heidi Barnes KEYSIGHT TECHNOLOGIES Electromagnetic (EM) solvers based on Maxwell's equations have proven invaluable in the advancement of digital electronics and wireline communications. Plain and simple, electrical engineers need to know what a cir- cuit or electrical interconnect will do when excited by a dynamic or varying signal. In the signal integrity world, an interconnect that passes a DC connectivity check can completely fail at higher frequencies. In the power integ- rity world, a power rail that measures the cor- rect DC voltage could easily go into oscillation when a dynamic load is applied. Learning the basic skills to fire up an EM simulator, obtain qualitative answers in minutes, and higher fidel- ity answers in a few days, can be the difference between sleepless nights of product failures vs. robust designs with wide design margins. The Practical Side of Using EM Solvers Figure 1: 3D EM simulators like PathWave ADS SIPro and PIPro make it easy to select nets and auto assign ports for fast EM setup and simulation. EM current density results on the right for a DDR4 DIMM board show how the power delivery at 10 kHz comes from the J1 edge connector, but at the higher 10 MHz frequency the power is being delivered by the on-board capacitors.