MOSFET High-Frequency Noise Control – Made in India Guide
High-frequency switching is what makes MOSFETs great for SMPS and motor drivers—but it also introduces unwanted noise, EMI (electromagnetic interference), and circuit instability. For Indian electronics enthusiasts and engineers, mastering noise control is critical for reliable, clean performance.
🔧 The Problem: High-Frequency Ringing and EMI
When a MOSFET switches rapidly (especially in MHz-range circuits), it can generate ringing and voltage spikes on the drain due to parasitic inductance and capacitance. This not only reduces efficiency but also affects nearby components like sensors and MCUs.
✅ The Solution: Add Gate Resistors and Snubber Circuits
To fix this, use a gate resistor (10–100Ω) to slow down the switching edges, and add a RC snubber across the MOSFET’s drain-source terminals to absorb transients. Also, ensure short PCB traces and proper grounding.
🔍 Practical Example: DIY Motor Driver
You’re building a 24V motor driver using an N-channel MOSFET. Without a gate resistor, your oscilloscope shows ringing over 10V during switching. By adding a 47Ω gate resistor and a 100nF/100Ω snubber, the spikes vanish—motor runs quietly and reliably.
🧮 Sample Calculation: Gate Resistor Power
Vgs = 10V, gate resistor = 47Ω, switching freq = 20kHz
Energy per switch ≈ ½ × Cg × V² = ½ × 100nF × 10² = 5µJ
Total power ≈ 5µJ × 20kHz = 0.1W → use 0.25W resistor.
🛒 Product Suggestion: Made in India Components
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