A Comparative Study on Power Delivery Network (PDN) Using Several Capacitor-Embedded Substrates for Next Generation Power Supply Applications

Power delivery network (PDN) performance of two types of embedded Multi-Layer Ceramic Capacitor (eMLCC) substrates and an embedded multi-array capacitor substrate called capacitor-type integrated Package Solution (iPaS) have been compared to reveal their suitability for power supply applications. This work greatly contributes on selecting the optimal solution depending on the application systems. In this paper, the results of PDN impedance simulation on each substrate model and transient response simulation using them will be described, and their suitability for power supply applications is discussed with the consideration of their features. For eMLCC, two types of substrates have been studied: a model in which output current goes through the external electrodes of MLCCs (eMLCC Type-A) and a model in which output current does not go through those of MLCCs (MLCC Type-B). From the comparison of the frequency dependence of impedance on these two substrates, it is confirmed that eMLCC Type-A shows lower impedance in all frequency bands. When comparing eMLCC substrates with an iPaS substrate, the impedance of eMLCC, which can be placed a large capacitance, is lower in the low frequency band, while the impedance of iPaS shows the lowest in the high frequency band of over 10 MHz. Since it depends on the application performance which band of impedance reduction is most important, transient response simulations have been performed for the power supply module constructed using these substrates under various load slew rate conditions. As a result, it is clarified that the eMLCC is suitable for applications with low slew rate because the effect of impedance in the low frequency band is dominant to the voltage-droop in that case. On the other hand, in applications with high slew rate and large current volume, the impedance in the high frequency band affects a lot to the voltage-droop, and iPaS is found to be the most effective solution. This study makes it possible to select the optimal solution depending on the application system's performance and will open the door to the next generation high-performance power supply systems.