Impact of VLSI Technology

1
Impact of VLSI Technology

• Yu Hen Hu

2
Outline

• Scaling of VLSI Technology
• Scaling Effect on Circuit Parameters
• Scaling Effect on Programmable VSP Architecture

3
MOS Scaling Effect

• Devise dimensions
• Supply voltage
• Substrate doping
• Current per device
• Gate capacitance
• Transistor on-resistance
• Intrinsic gate delay
• Power dissipation per gate
• Area per device

• 1/s (sgt1)
• 1/s
• s
• 1/s
• 1/s
• 1
• 1/s
• 1/s2
• 1/s2

4
Video Signal Processing Architecture

• ASC (TI), IDSP (NTT)
• Multiple, pipelined arithmetic units,
• Interleaved dual-port memory.
• VSP1 (Philips)
• Crossbar connection of memory and Pes
• MVP (TI 32080)
• 1 RISC core (floating point), 4 DSP PEs with
  integer units, 4 memory modules.
• Crossbar interconnection switches.

5
Scaling Effects on Circuit/Architecture

• Interconnect cross section
• Long wire chip size
• Long wire delay
• short wire delay
• Processor delay
• Memory delay/Proc. delay

• 1/s2
• sm
• AsmB/s
• 1
• 1/s
• Cs D

6
Interconnection Delay

• Elmore delay
• t1 R1(C1C2C3C4)R2(C2C3C4)R3C3

OUT1
R1
R2
R3
C3
C2
C1
R4
C4
7
Interconnection Delay (2)

• R ? L/(WH) ? s
• C ? L (W/toxf H/Dh) ? 1/s
• Hence RC time constant is independent of scaling!
• However, as scaling factor s increases, often
  chip area does not descrease, and rather
  increases. Hence the global wires (e.g. clock)
  will have added delay (a factor sm) as a result
  of scaling!

8
Impacts on Architecture

• Processor delay reduces (1/s) since transistor
  gate delay smaller, clock higher, voltage lower
• Memory delay is determined by the BIT line. It
  should reduce if memory size unchanged. But will
  increase if memory size increases.
• Interconnection network delay will stay the same
  or larger (when larger network used)

9
Conclusion

• Scaling of device parameter will impact on
  circuit parameters (delay) which in turn impact
  on architectural decisions.
• As devices feature sizes continue to shrink, new
  architectural style must be developed to exploit
  most benefit from scaling.