A digital CMOS IC operating at 10 MHz clock frequency consumes 100 mW power; the same IC operating at 15 MHz clock frequency consumes 140mW power. What is the static power consumption of the IC?

A digital CMOS IC operating at 10 MHz clock frequency consumes 100 mW power; the same IC operating at 15 MHz clock frequency consumes 140mW power. What is the static power consumption of the IC? Correct Answer 20 mW

Concept:

Static power is proportional to the static current, i.e. the current that flows regardless of gate switching.

Dynamic Power is related to the current that flows when switching takes place and is given by for CMOS as:

P = fCV²_cc

Or P = Kf (where K = V_cc²C)

Power consumed by CMOS = P_static + P_dynamic

Calculation:

For f₁ = 10MHz, P_consumed = 100 mW = P₁ (Let)

For f₂ = 15MHz, P_consumed = 140 mW = P₂

⇒ P₁ = P_static + P_dynamic

⇒ 100 mW = P_static + Kf₁

⇒ 100 mW = P_static + K(10 M) …1)

Similarly, P₂ = 140 mW = P_static + K(15 M) …2)

From equation (i) and (ii)