(A) fast and accurate crosstalk-included eye-diagram estimation method considering data bus inversion (DBI) function in high bandwidth memory (HBM) channel

Abstract

In this research, a fast and accurate crosstalk-included eye-diagram estimation method considering Data Bus Inversion (DBI) function in High Bandwidth Memory (HBM) channel is proposed. HBM has 1024 I/Os to achieve TB/s data transmission, however, HBM can be suffered from the significant crosstalk effects. The proposed estimation method includes crosstalk effects from adjacent channels which can considerably degrade the transmitted signal. This method enables to estimate worst and statistical eye-diagrams in a short time with high accuracy. While PRBS (Pseudo Random Binary Sequence) simulation has been used for accurate estimation of the channel characteristics, it requires substantial amount of computational time and resources. Therefore, in order to reduce the eye-diagram estimation time, superposition and convolution of the 8 boundary responses of the channel is used. The proposed method is verified by time-domain simulations and measurements at data rates of up to 4 Gbps. According to the estimated crosstalk-included eye-diagrams, the proposed method reduces simulation time over 99% and shows a high accuracy of approximately 93%. In addition, the proposed method can consider Data Bus Inversion (DBI) function, which is used in HBM to reduce crosstalk effects. DBI function inverts the bit transition if the number of transition in a Byte, 8 bit channels, is more than 4. Then, the worst crosstalk effects will be reduced by 4. The proposed method reduces 77% simulation time and shows more than 92% accuracy in time-domain simulation results. Since the proposed method is based on the superposition and convolution of 8 boundary responses, it can be applied to various coupled channels. Thus, the proposed method is applied and compared the Single-ended/Differential Signaling and Silicon/Organic/Glass interposer. As a result, the proposed crosstalk-included eye-diagram estimation method considering DBI function can be used widely for high-speed and wide I/O interposer channel on 2.5D and 3D IC.