Fig. 1. Basic architecture of the 400 Gbit/s QSFP-DD optical module

Fig. 2. Simulation model and equivalent circuit

Fig. 3. The influence of the radius of each layer back pad of differential hole on the transmission performance

Fig. 4. Simulation model of the inner BGA connection structure

Fig. 5. Influence of inner BGA connection structure anti pad on transmission performance

Fig. 6. Five different anti pad shapes and vias places of the inner BGA connection structure

Fig. 7. 7　SDD₂₁ simulation results of the inner BGA connection structure with five different anti pad shapes and vias places

Fig. 8. Simulation model of optical module PCB high-speed channel

Fig. 9. Mixed-mode S-parameters of 3 groups of high-speed channel on optical module PCB

Fig. 10. Simulated eye diagram results of optical module PCB high-speed channel

Fig. 11. Test platform of optical module

Fig. 12. SDD₁₁ test results of optical module in high speed channel

Fig. 13. Comparison of simulation and test results of impedance distribution in high speed channel of optical module