Leakage Current

Definition: Leakage current is the undesired flow of current in a transistor when it is supposed to be off.

Key Points:

  • Major contributor to static power consumption in modern CMOS technology
  • Increases as transistor sizes shrink and threshold voltages decrease
  • Main types: subthreshold leakage and gate oxide leakage
  • Worsens at higher temperatures

Mitigation Techniques:

  • Power gating
  • Use of high-k dielectrics
  • Multi-threshold CMOS (MTCMOS)
  • Reverse body bias

Impact:

  • Significant in deep submicron processes
  • Limits the scaling of supply voltage
  • Critical concern in battery-operated devices

Leakage current management is crucial in modern VLSI design for power efficiency.