The Screening Method of Board-Level Decoupling Capacitors for Multi-Power Distribution Network

The simultaneous connection and disconnection of multiple transistors in the chip can cause voltage fluctuations in the power distribution network (PDN), known as simultaneous switching noise (SSN). Inserting decoupling capacitors into integrated circuits to lower circuit impedance is a common method to reduce SSN. While, these methods (such as the “Multipole” method and Big “V” method) still cannot reduce the power supply impedance well, leading to the unstable function of the circuit during operation. To address this issue, we propose a method to reduce voltage fluctuations of multi-power supply by screening the value of decoupling capacitors (Decaps) and then improving the multi-power distribution network to reduce the power impedance below the target impedance. For validation, a series of simulations are carried out in the board-level circuit, the experimental results demonstrate that the design scheme outperforms the mainstream Big “V” method and the “Multi-pole” method, which can reduce the highest impedance by about 19.8%~47.2% in the simulation frequency range.