Topic: Digital Electronics
A digital CMOS IC operating at 10 MHz clock frequency consumes 100 mW power; the same IC operating at 15 MHz clock frequency consumes 140 mW power. What is the static power consumption of the IC?
- A. 10 mW
- B. 15 mW
- C. 20 mW
- D. 40 mW
Answer: C. 20 mW
Explanation: Total power $P = P_{static} + P_{dynamic}$. Dynamic power is proportional to frequency ($P_{dynamic} = Kf$).
At $10\text{ MHz}$: $100 = P_{static} + 10K$ (Eq. 1)
At $15\text{ MHz}$: $140 = P_{static} + 15K$ (Eq. 2)
Subtracting Eq. 1 from Eq. 2 gives $40 = 5K \Rightarrow K = 8$.
Substitute $K$ back into Eq. 1: $100 = P_{static} + 10(8) \Rightarrow P_{static} = 100 - 80 = 20\text{ mW}$.