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ELEC 7770 Advanced VLSI Design Spring 2010 Interconnects and Crosstalk. Vishwani D. Agrawal James J. Danaher Professor ECE Department, Auburn University Auburn, AL 36849 vagrawal@eng.auburn.edu http://www.eng.auburn.edu/~vagrawal/COURSE/E7770_Spr10. Crosstalk.
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ELEC 7770Advanced VLSI DesignSpring 2010Interconnects and Crosstalk Vishwani D. Agrawal James J. Danaher Professor ECE Department, Auburn University Auburn, AL 36849 vagrawal@eng.auburn.edu http://www.eng.auburn.edu/~vagrawal/COURSE/E7770_Spr10 ELEC 7770: Advanced VLSI Design (Agrawal)
Crosstalk Signal noise due to coupling between interconnects. Victim – affected interconnect; Aggressor(s) – noise causing interconnect(s). Principal cause – capacitive coupling in long parallel wires. Transients behavior. Simulation for functional verification. Avoidance by physical design, perpendicular wires, shielding. ELEC 7770: Advanced VLSI Design (Agrawal)
Victim and Aggressors Ceff = Cg + 2C0 1 V 2 0→VDD 0V 0V C0 C0 Cg ELEC 7770: Advanced VLSI Design (Agrawal)
Victim and Aggressors Ceff = Cg 1 V 2 0→VDD 0→VDD 0→VDD C0 C0 Cg ELEC 7770: Advanced VLSI Design (Agrawal)
Victim and Aggressors Ceff = Cg + 4C0 1 V 2 0→VDD VDD→0 VDD→0 C0 C0 Cg ELEC 7770: Advanced VLSI Design (Agrawal)
Crosstalk Induced Capacitance ELEC 7770: Advanced VLSI Design (Agrawal)
Example • Time t < 0 • Victim at VDD, both neighbors at VDD • Charge on victim = Cg VDD • Time t = 0 • Both neighbors switch, VDD → 0 • Victim’s effective capacitance, Cg + 4C0 • Victim’s voltage = Cg VDD/(Cg + 4C0) < VDD • Time t > 0 • Victim charges to VDD ELEC 7770: Advanced VLSI Design (Agrawal)
Example (Cont.) VDD Victim’s voltage Cg VDD/(Cg + 4C0) 0 Time, t ELEC 7770: Advanced VLSI Design (Agrawal)
Reducing Crosstalk GND 1 VDD 2 GND ELEC 7770: Advanced VLSI Design (Agrawal)
References J. E. Ayers, Digital Integrated Circuits Analysis and Design, Second Edition, Boca Raton: CRC Press, 2010, Chapter 7. X. Chen and N. A. Touba, “Fundamentals of CMOS Design,” Chapter 2, L.-T. Wang, Y.-W. Chang and K.-T. Cheng (Editors), Electronic Design Automation, Morgan-Kaufmann, 2009. pp. 39-95. H. Grabinski, Interconnects in VLSI Design, Springer, 2000. ELEC 7770: Advanced VLSI Design (Agrawal)