Blog Post: MOSFET Gate Noise Control – Made Simple!
🎯 The Problem: Gate Noise in MOSFETs
MOSFETs switch fast—but that’s also the problem! When the gate voltage changes too quickly, it creates electrical noise and ringing. This can cause false switching, EMI issues, or even damage other sensitive parts of your circuit.
🔧 The Solution: Gate Resistor to the Rescue
A simple and effective fix is to add a gate resistor (usually 10–100Ω) in series with the MOSFET gate. This slows the charging and discharging of the gate capacitance, dampening oscillations and reducing EMI. Bonus: It adds protection for your microcontroller or driver IC too.
🧪 Practical Example :
Let’s say you’re switching a motor with an IRF540N MOSFET, driven by a microcontroller. Without a gate resistor, you might notice erratic switching due to noise. Add a 22Ω gate resistor and the ringing is gone—your motor runs smoother and your system becomes more reliable.
🔢 Sample Calculation :
To limit the gate charge current:
Gate Charge (Qg) = 71nC,
This safely limits inrush and controls switching speed.
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