An Analysis on the Effectiveness of 2 and 3 Terminal Capacitors in PDN Design

The parasitic inductance of a capacitor depends on its physical structure. Due to the geometry of 3-terminal capacitors, they boast a lower parasitic inductance compared to 2-terminal capacitors of the same and possibly smaller package sizes. While the parasitic inductance of a single 3-terminal capacitor may be lower, using multiple 2-terminal capacitors may result in similar performance. In this work, the inductance of 2-terminal (0201, nominal 2.2 uF) and 3-terminal (0402, nominal 4.3 uF) capacitors is extracted and compared through measurements. From our de-embedding method and characterized capacitors, the inductance of 2-terminal capacitors is only about ~20 pH higher than the characterized 3terminal capacitor. On a power net of a real product, 3-terminal capacitors of the same type as characterized were replaced with 2-terminal capacitors of the same type as characterized. From measurement results, the measured inductance at 100 MHz is lower by only about 3.45 pH, or 2.62%, when using 3-terminal capacitors.