Power Dissipation

Question 1

What’s the general definition of power?

Answer 1

Rate (speed) of consuming (or generating) energy.

Question 2

What’s the general power equation, in different forms?

Answer 2

Power (watts) = Energy / Time
P = VI watts
P = I2R

Question 3

What are the two ways that CMOS logics consume power?

Answer 3

Static and dynamic

Question 4

1. What is the static power consumption of a CMOS logic?

2. What is the dynamic (or transient) power dissipation of a CMOS logic?

Answer 4

1. Solely due to leakage current.

2. Due to the switching of CMOS logics.

Question 5

For repetitive square waves, what is the dynamic power equation?

Answer 5

Dynamic power = CL * Vdd2 * F watts
= Load Capacitance * vdd2 * frequency watts
Dependent on the output loading (or fanout), the power supply voltage, and the operating frequency.

Question 6

What is a transfer curve?

Answer 6

Shows how an output voltage changes in response to an input voltage change.