Analysis and optimization of multibranch interconnect architecture based on multi-port transfer matrix

Abstract

Multi-branch interconnect architecture (MBIA) is an effective way to achieve ultra-high-speed and ultra-high-integration 
electrical systems. However, the increasing frequency and complexity of operation result in critical signal integrity (SI) issues. 
The majority of existing studies focuses on modeling and analyzing the architecture itself but ignore corresponding termination 
effects thereby resulting in inaccurate analysis and ineffective 
optimization. To analyze and optimize MBIA accurately and effectively, the present study proposed a multi-port transfer matrix 
(MPTM) that considered termination effects into account, and a 
hybrid time-frequency domain strategy based on MPTM was also 
developed. First, MBIA was modeled as two cascaded generalized 
multi-port networks that respectively represented MBIA and its 
terminations. Second, MPTM was defined and MPTM-based strategy was derived. Finally, the principle and performance of the 
proposed strategies were demonstrated through an eight-DDR3 
address interconnect of fly-by topology with a line rate of up to 
667 Mbps. The simulation results verifies that the proposed MPTM 
represents a complete MBIA by considering termination effects 
and provides effective bias for analysis and optimization. According to the MPTF-based analysis and optimization strategy, by adding a specific capacitor near the transmitter output, the simulated 
eye height of the address signal attains an average growth rate of 
80% of the original design, and this optimaizaiton aslo achieves 
steady performance in real projects. The results obtained in this 
study can be applied to obtain the optimal performance and stability of electrical systems involving MBIA.
Keywords: Multi-branch interconnect, multi-port, transfer 
function,scattering matrix, termination effects.