MOSFET Calculator with Steps
Calculate Drain Current (ID) and identify the operating region.
What is a MOSFET Calculator?
A MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) calculator is a specialized tool used by electronics engineers and students to determine the electrical behavior of a MOSFET. By inputting parameters like the Threshold Voltage, Gate-Source Voltage, and Drain-Source Voltage, the calculator determines if the transistor is in the Cutoff, Triode (Linear), or Saturation region.
Operating Regions Explained
Understanding the regions is critical for circuit design:
- Cutoff Region: Occurs when VGS < Vth. The transistor is "OFF" and no current flows through the drain.
- Triode (Linear) Region: Occurs when VGS ≥ Vth and VDS < (VGS - Vth). In this state, the MOSFET acts like a voltage-controlled resistor.
- Saturation Region: Occurs when VGS ≥ Vth and VDS ≥ (VGS - Vth). This is used for amplification as the current remains relatively constant regardless of VDS.
How to Use This Calculator
To use this tool, simply input your transistor's specifications from its datasheet. Enter the Threshold Voltage (Vth), the applied voltages (VGS and VDS), and the transconductance parameter (kn). The tool will instantly provide the Drain Current (ID) and show you the exact mathematical steps taken to reach the result, including the Overdrive Voltage calculation.
FAQs
What is kn? It is the conduction parameter, often calculated as ½ μnCox(W/L) depending on the textbook convention. This tool treats kn as the multiplier used in the standard current equations.
Why is my Drain Current zero? If your VGS is lower than the Threshold Voltage, the channel has not formed, and the device is in the Cutoff region.