1. Coupling and Cross-talk Analysis in High Speed Interconnects
Md Amimul Ehsan
Electrical Engineering and Computer Science Department,
University of Kansas
December 01, 2015

2. Outlines Motivation Introduction Signal/Ground Via
Near and Far end crosstalk
Optimized and non-optimized S/G Via
Conclusion

3. Motivation
Due to technology miniaturization, crosstalk is becoming increasingly becoming major concern in high speed designs.
Higher integration density, causes electromagnetic radiation in device space.
Merging process technology, mixed materials, system integration.
Coupling noise between the vias is a significant design consideration.

4. Objectives
Study on coupling and crosstalk which is critical for signal integrity.
Investigation of via physical dimensions on induced crosstalk.
Near end crosstalk (NEXT) and Far end crosstalk (EFXT) are analyzed for single ended and differential signal via.

5. Fig. 1: Examples of crosstalk; two conductors sharing same ground [1]
Introduction
Electromagnetic interference that disturbs neighbor is the crosstalk noise.
The time changing electric and magnetic field in signal conductor induce energy to propagate along victim conductor.
Fig. 1: Examples of crosstalk; two conductors sharing same ground [1] 2D

6. Impacts of Via Dimensions
Placement of signal and ground via.
Via radius.
Via pitch
Oxide insulator thickness (For TSV in 3D IC)

7. Signal/Ground Via Pattern
Fig. 2. Via arrangement 4 single ended signals with 12 grounds
Fig. 3. Via arrangement 4 single ended signals with 12 grounds (HFSS)

8. Single Ended Via Crosstalk
Fig. 4. Near End Crosstalk of single ended signal Via with different pitch
Fig. 5. Far End Crosstalk of single ended signal Via with different pitch

9. Differential Via Crosstalk
Fig. 6. Near End Crosstalk of single ended and differential Via
Fig. 7. Far End Crosstalk of single ended and differential Via

10. Optimized Differential S/G Via
Fig. 8. Differential signal assignment of non- optimized TSV
Fig. 9. Differential signal assignment of optimized TSV

11. Crosstalk Comparison V_NEXT (Volts) V_NEXT (Volts) Time (µs) Time (µs)
Time = nsec
V_NEXT = Max m1
Time = nsec
V_NEXT = Min
V_NEXT (Volts)
Time (µs) m2
Time = nsec
V_NEXT = Max m1
Time = nsec
V_NEXT = Min
Time (µs)
V_NEXT (Volts)
Fig Step response simulation in near end crosstalk for non-optimized TSV pattern
Fig Step response simulation in near end crosstalk for optimized TSV pattern

12. Conclusion
This work investigated the via crosstalk noise under high speed operations and discussed the impacts of various factors affecting crosstalk.
An analytical model can be proposed that could capture the induced coupling noise.
The coupling and crosstalk can be analyzed from the equivalent circuit of the differential pin pattern and can be applied for the design of crosstalk suppression.

13. References
A. W. Barr, “Analyzing Crosstalk and Ground Bounce in Multiconductor Systems Using SPICE Circuit Simulations,” AMP Journal of Technology, Vol. 3, Nov
Yi, Y., Liu, Y., Zhou, Y., Becker, W.D Minimizing crosstalk in high-speed differential buses by optimizing power/ground and signal assignment. In proc. of 18th IEEE Elect. Perform. Electron. Packag. Sys., Oct
He, X., W. Wang, and Q. Cao, "Crosstalk modeling and analysis of Through-Silicon- Via connection in 3D integration," PIERS Proceedings, , Taipei, Mar ,
Qian, L., Xia, Y., Liang, G Study on crosstalk characteristic of carbon nanotube through silicon vias for three dimensional integration. Microelectronics Journal, 46, 7, (July 2015), 572–580.
Engin, A.E.; Narasimhan, S.R., "Modeling of Crosstalk in Through Silicon Vias," in Electromagnetic Compatibility, IEEE Transactions on , vol.55, no.1, pp , Feb. 2013

14. Thank you