Interview Question - Low power design

As temperature increases, does the power consumed by a typical combinational circuit increase, stay the same, or decrease? Briefly justify your answer.

Sol:
Short circuiting power will increase because:

• As temperature increases, atoms vibrate more, and so have greater probability of colliding with electrons flowing with current.
• This increases resistivity, which increases delay.
• Signals will rise and fall more slowly, which will increase the short circuiting time, and hence increase short circuiting power

Switching power will increase because of increased resistivity