What is activity factor in CMOS?

Activity factor indicates how frequently the output of a gate changes state. Every state change involves either the charging or the discharging of the load capacitor, leading to dynamic power consumption. Short-circuit power in a CMOS gate occurs when: a. The output of the gate changes state.

What is the power dissipation of CMOS?

The total power dissipation in a CMOS circuit can be expressed as the sum of three main components: Static power dissipation (due to leakage current when the circuit is idle) Dynamic power dissipation (when the circuit is switching) Short-circuit power dissipation during switching of transistors.

Which of the following is a factor in CMOS total power consumption?

The dynamic power consumption of a CMOS IC is calculated by adding the transient power consumption (PT), and capacitive-load power consumption (PL). Transient power consumption is due to the current that flows only when the transistors of the devices are switching from one logic state to another.

What is the activity factor of a signal?

Switching Activity Factor (A) of a circuit node is the probability the given node will change its state from 1 to 0 or vice versa at a given clock tick. Activity factor is a function of the circuit topology and the activity of the input signals.

How is activity factor calculated in CMOS?

Therefore, the probability of a 0->1 transition is 1/4 (probability of 0)*3/4 = 3/16. In this case, the load capacitance is charged and stores energy during 3/16 of all input transitions. This fraction is called the activity factor or alpha. With activity factor alpha, P is reduced to P = alpha*1/2*C*(V^2)*f.

Why is power dissipation important?

Power dissipation considerations have become important not only from reliability point of view, but they have assumed greater importance by the advent of portable battery driven devices like laptops, cell phones, PDAs etc. When power is dissipated, it invariably leads to rise in temperature of the chip.

What is power consumption in VLSI?

Abstract. Space, power consumption and speed are major design issues in VLSI circuit. The design component has conflicting affect on overall performance of circuits. It is found that algorithm based design reduce gate switching activity considerably and as result power consumption in multiplier is reduced.

What is the basis of power consumption in VLSI circuit?

The dynamic power consumption of the circuit directly depends on the physical capacitance being switched. So, over and above reducing voltage, reducing capacitance can be another way to achieve lower dissipation.