MOSFET Gate Drive Power

Pd = Qg × Vgs × f

Quick answer

This calculator solves Pd = Qg × Vgs × f for Gate Drive Power. With Total Gate Charge 10 nC, Gate-Source Voltage 12 V, Switching Frequency 100 kHz, the result is 12 mW. It solves in 4 directions, so you can enter the values you have and get the one you need.

Calculator

Gate Drive Power (mW)
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Formula

Pd = Qg × Vgs × f

Description

Every switching cycle, the MOSFET gate capacitance must be charged to Vgs and then discharged back to zero. The energy per cycle is Qg × Vgs, and multiplying by the switching frequency gives the average power dissipated in the gate driver circuit. This power is independent of the drain current and is dissipated entirely in the gate driver (not in the MOSFET itself). At high switching frequencies with large MOSFETs (high Qg), gate drive losses can become significant and must be included in the total loss budget.

Variables

  • Pd — Average gate drive power loss (W)
  • Qg — Total gate charge per switching cycle (C)
  • Vgs — Gate drive voltage (V)
  • f — Switching frequency (Hz)

Practical Notes

Typical Qg values: small signal MOSFET 1-10 nC, medium power 10-50 nC, high power 50-500 nC. Gate drive power comes from the gate driver supply, not the power stage. Half-bridge gate drivers need bootstrap capacitors for the high-side gate. GaN transistors have much lower Qg than silicon for the same Rds(on), enabling higher switching frequencies.

Symbols and units

Symbol Meaning Default unit Accepted units
Pd Gate Drive Power mW µW, mW, W, kW
Qg Total Gate Charge nC pC, nC, µC, mC, C
Vgs Gate-Source Voltage V pV, nV, µV, mV, V, kV
f Switching Frequency kHz Hz, kHz, MHz, GHz

Step by step

  1. 1. What you know: Total Gate Charge 10 nC, Gate-Source Voltage 12 V, Switching Frequency 100 kHz
  2. 2. The relation: Pd = Qg × Vgs × f
  3. 3. Substitute: Qg = 10 nC, Vgs = 12 V, f = 100 kHz
  4. 4. Result: Gate Drive Power = 12 mW

Worked examples

Minimum range

Given: Total Gate Charge 100 pC, Gate-Source Voltage 0.33 V, Switching Frequency 100 Hz

Result: Gate Drive Power = 0.0033 µW

Low range

Given: Total Gate Charge 1 nC, Gate-Source Voltage 3.3 V, Switching Frequency 1 kHz

Result: Gate Drive Power = 3.3 µW

Typical

Given: Total Gate Charge 10 nC, Gate-Source Voltage 12 V, Switching Frequency 100 kHz

Result: Gate Drive Power = 12 mW

High range

Given: Total Gate Charge 100 nC, Gate-Source Voltage 0.23 kV, Switching Frequency 0.5 MHz

Result: Gate Drive Power = 11.5 W

Maximum range

Given: Total Gate Charge 1 µC, Gate-Source Voltage 2.3 kV, Switching Frequency 5 MHz

Result: Gate Drive Power = 11.5 kW

Solving for each variable

Solve for Gate Drive Power

Total Gate Charge 100 pC, Gate-Source Voltage 0.33 V, Switching Frequency 100 Hz → 0.0033 µW

Solve for Total Gate Charge

Gate Drive Power 100 µW, Gate-Source Voltage 0.33 V, Switching Frequency 100 Hz → 3.03 µC

Solve for Gate-Source Voltage

Gate Drive Power 100 µW, Total Gate Charge 100 pC, Switching Frequency 100 Hz → 10 kV

Solve for Switching Frequency

Gate Drive Power 100 µW, Total Gate Charge 100 pC, Gate-Source Voltage 0.33 V → 3.03 MHz

How Gate Drive Power changes with Total Gate Charge

Total Gate Charge (input) Gate Drive Power (result)
1 nC 1.2 mW
2.5 nC 3 mW
5 nC 6 mW
7.5 nC 9 mW
10 nC 12 mW
15 nC 18 mW
20 nC 24 mW
40 nC 48 mW
70 nC 84 mW
100 nC 120 mW

The same result in other units

Unit Value
µW 12000
mW 12
W 0.012

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Frequently asked questions

How do you calculate MOSFET Gate Drive Power?

Use Pd = Qg × Vgs × f. With Total Gate Charge 10 nC, Gate-Source Voltage 12 V, Switching Frequency 100 kHz, Gate Drive Power works out to 12 mW.

What is the formula for MOSFET Gate Drive Power?

The formula is Pd = Qg × Vgs × f. Every switching cycle, the MOSFET gate capacitance must be charged to Vgs and then discharged back to zero.

How do you find Total Gate Charge when you know the other values?

Rearrange for Total Gate Charge: with Gate Drive Power 100 µW, Gate-Source Voltage 0.33 V, Switching Frequency 100 Hz, Total Gate Charge is 3.03 µC.

How do you find Gate-Source Voltage when you know the other values?

Rearrange for Gate-Source Voltage: with Gate Drive Power 100 µW, Total Gate Charge 100 pC, Switching Frequency 100 Hz, Gate-Source Voltage is 10 kV.

What units does MOSFET Gate Drive Power use?

Gate Drive Power is shown in µW, mW, W. Values are held in SI base units internally, so you can mix prefixes without converting by hand.

Related Concepts

All Semiconductors formulas →
MOSFET Conduction Loss MOSFET Switching Loss BJT Total Dissipation Diode Power Loss Zener Regulation Resistor Transistor Current Gain (β) MOSFET Gate Drive Power MOSFET Rds(on) vs Temperature

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