Dynamic power expression?

Dynamic power expression?

• A. Frequency, capacitance, and voltage squared.
• B. Leakage current.
• C. Ambient temperature.
• D. Idle time.

Answer: (A)

Dynamic power in digital circuits comes from charging and discharging capacitances each time signals toggle. The energy per toggle is proportional to C V^2, where C is the switched capacitance and V is the supply voltage. If these toggles occur at a rate f, the average power is proportional to f times C times V^2 (often written with an activity factor α: P_dyn ≈ α C V^2 f). So the dynamic power expression depends on frequency, capacitance, and the square of the supply voltage. That’s why the option listing frequency, capacitance, and voltage squared is the correct fit. Leakage current represents static power, not the dynamic switching power. Ambient temperature affects leakage, not the main dynamic-power relationship, and idle time relates to how often the circuit actually toggles (activity), which is captured by the activity factor but isn’t the primary form of the dynamic-power expression itself.

Dynamic power in digital circuits comes from charging and discharging capacitances each time signals toggle. The energy per toggle is proportional to C V^2, where C is the switched capacitance and V is the supply voltage. If these toggles occur at a rate f, the average power is proportional to f times C times V^2 (often written with an activity factor α: P_dyn ≈ α C V^2 f). So the dynamic power expression depends on frequency, capacitance, and the square of the supply voltage. That’s why the option listing frequency, capacitance, and voltage squared is the correct fit.

Leakage current represents static power, not the dynamic switching power. Ambient temperature affects leakage, not the main dynamic-power relationship, and idle time relates to how often the circuit actually toggles (activity), which is captured by the activity factor but isn’t the primary form of the dynamic-power expression itself.