Power dissipation

• Explain the static and dynamic power dissipation in CMOS circuits with necessary diagrams and expressions.
• What are the sources of power dissipation in CMOS and discuss various design techniques to reduce power dissipation in CMOS?
• Derive an expression for dynamic power dissipation.

The instantaneous power P (t) consumed by a circuit element is the product of the current and the voltage of the element

P (t ) = I (t )V (t )

The energy consumed over time interval T is the integral of the instantaneous power

• This is called the dynamic power because it arises from the switching of the load.
• Because most gates do not switch every clock cycle, it is often more convenient to express switching frequency fsw as an activity factor α times the clock frequency f.
• The dynamic power dissipation may be rewritten as