Static vs dynamic contrast.

Static vs dynamic contrast.

• A. Static power is consumed in idle due to leakage; dynamic power is consumed during switching.
• B. Static power is due to charging; dynamic power is leakage.
• C. Static power scales with f; dynamic power scales with leakage.
• D. Static power is zero when powered.

Answer: (A)

Static power vs dynamic power describes two ways a digital circuit uses energy. Static power is the energy drawn even when nothing is changing, coming mainly from leakage currents that flow through transistors while the circuit is idle. Dynamic power, on the other hand, is the energy spent when signals actually switch, as the circuit’s capacitive loads must be charged and discharged with each transition. Why the correct description fits: static power being consumed in idle due to leakage captures the reality that circuits keep drawing current even when no activity is happening. Dynamic power being consumed during switching reflects that every time a node toggles, power is used to move charge onto and off of those capacitive loads, with the energy per transition roughly proportional to C·V², and the total dynamic power proportional to how often switching occurs (frequency) and how active the circuit is. Context to help understanding: static power is roughly I_leak·V and is present whenever the circuit is powered, regardless of how fast it runs. dynamic power is mostly about switching activity and scales with frequency and voltage, since more frequent toggling and higher voltages mean more charging/discharging events. The other statements mix up where leakage and charging occur and misstate how power depends on frequency and leakage, so they don’t align with how static and dynamic power behave.

Static power vs dynamic power describes two ways a digital circuit uses energy. Static power is the energy drawn even when nothing is changing, coming mainly from leakage currents that flow through transistors while the circuit is idle. Dynamic power, on the other hand, is the energy spent when signals actually switch, as the circuit’s capacitive loads must be charged and discharged with each transition.

Why the correct description fits: static power being consumed in idle due to leakage captures the reality that circuits keep drawing current even when no activity is happening. Dynamic power being consumed during switching reflects that every time a node toggles, power is used to move charge onto and off of those capacitive loads, with the energy per transition roughly proportional to C·V², and the total dynamic power proportional to how often switching occurs (frequency) and how active the circuit is.

Context to help understanding: static power is roughly I_leak·V and is present whenever the circuit is powered, regardless of how fast it runs. dynamic power is mostly about switching activity and scales with frequency and voltage, since more frequent toggling and higher voltages mean more charging/discharging events.

The other statements mix up where leakage and charging occur and misstate how power depends on frequency and leakage, so they don’t align with how static and dynamic power behave.