Signal Integrity Design and Analysis of Redistribution Layer Interposer Channel with Diagonal Meshed Ground in Memory Interface of High Bandwidth Memory

In this paper, we designed and analyzed redistribution layer (RDL) interposer channel with with diagonal meshed ground (dia-GND) in memory interface for high bandwidth memory (HBM). Therefore, the RDL interposer is emerged to solve cost and electrical performance. However, the RDL interposer memory channels have a critical signal integrity (SI) issue at high datarate. Specifically, RDL interposer channels with orthogonal meshed ground (ortho-GND) has impedance mismatch because of low channel capacitance which also causes severe overshoot voltage. To overcome this issues, we proposed dia-GND for RDL interposer channels. We analyzed SI of the proposed RDL interposer memory channels in the frequency and the time domain and compared with ortho-GND. As a result, it showed improved not only insertion loss (IL), return loss (RL) and crosstalk but also overshoot voltage which is improved 50% with dia-GND.