Example Data Table
| Case |
Vdd |
Capacitance |
Frequency |
Activity |
Leakage Current |
Total Power |
| Low power block |
0.9 V |
8 pF |
250 MHz |
0.18 |
4 µA |
About 296 µW |
| Balanced logic |
1.1 V |
20 pF |
500 MHz |
0.25 |
12 µA |
About 3.86 mW |
| Fast core path |
1.2 V |
45 pF |
1 GHz |
0.35 |
30 µA |
About 25.45 mW |
Formula Used
Dynamic switching power: Pdyn = α × Ctotal × Vdd² × f × Dactive.
Clock network power: Pclock = αclock × Cclock × Vdd² × f × Dactive.
Short-circuit power: Pshort = Pdyn × short-circuit percent ÷ 100.
Leakage power: Pleak = Vdd × Ileak × leakage multiplier × Dleak.
Total power: Ptotal = Pdyn + Pclock + Pshort + Pleak.
Energy: E = Ptotal × runtime.
How To Use This Calculator
- Enter the supply voltage used by the circuit.
- Add switched capacitance per node and the node count.
- Enter activity factor, frequency, and active duty.
- Add clock capacitance percentage if clock loading matters.
- Enter leakage current and its temperature multiplier.
- Press calculate to view power, energy, shares, and heat rate.
- Use CSV or PDF export for reports and design notes.
Understanding Dynamic And Leakage Power
Modern digital circuits consume power in several ways. Dynamic power appears when internal nodes charge and discharge. It depends strongly on supply voltage, switched capacitance, activity, and frequency. Voltage is especially important because it is squared in the formula. A small voltage reduction can cause a large power drop. Frequency also matters. Faster clocks cause more switching events each second. Capacitance matters because every loaded node stores energy before it changes state.
Why Leakage Matters
Leakage power is different. It exists even when logic is not switching. It comes from small currents through transistors, gates, and reverse biased junctions. Leakage grows in smaller technology nodes. It also rises with temperature. That is why the calculator includes a leakage multiplier. You can use it for corner studies, hot silicon checks, or standby comparisons. Leakage duty helps model sleep states, gated domains, and partial shutdown modes.
Clock And Short-Circuit Effects
Clock networks often use large capacitance. They switch regularly, so their power can be high. This tool separates clock power from general dynamic power. That makes the result easier to audit. Short-circuit power is also included. It represents brief current flow during input transitions. It is entered as a percentage of dynamic power. This simple method works well for early estimates.
Design Use
Use this calculator during architecture planning, lab estimates, and teaching work. Compare several voltage and frequency points. Then watch how each share changes. A high dynamic share suggests voltage, frequency, activity, or capacitance optimization. A high leakage share suggests power gating, body biasing, lower temperature, or better standby design. The result is still an estimate. Real chips need simulation, layout extraction, and measurement. Yet this method gives a clear first view. It also supports quick reports with export buttons. Designers can document assumptions and compare cases before detailed signoff.
FAQs
What is dynamic power?
Dynamic power is the switching power used when circuit nodes charge and discharge. It depends on activity factor, capacitance, voltage squared, frequency, and active duty.
What is leakage power?
Leakage power is static power caused by leakage current. It can exist even when no useful switching happens. Temperature and process corners can increase it.
Why is voltage squared in the formula?
Charging a capacitor stores energy proportional to voltage squared. Because digital nodes charge repeatedly, dynamic power also follows the squared supply voltage term.
What activity factor should I use?
Use 1 for a node switching every cycle. Use lower values for realistic logic. Common early estimates use values between 0.05 and 0.30.
Why include clock power separately?
Clock trees can switch every cycle and drive large capacitance. Separating clock power helps show whether clock distribution dominates total power.
What is short-circuit power?
Short-circuit power occurs during switching transitions. For a short time, pull-up and pull-down devices can conduct together. This calculator models it as a percentage.
Can this replace circuit simulation?
No. It is best for estimates and comparisons. Final design work should use transistor simulation, extracted capacitance, timing data, and silicon measurements.
Why use a leakage multiplier?
The multiplier lets you model hot temperature, slow process, aging, or standby assumptions. It scales leakage current before leakage power is calculated.