MOSFET Threshold Voltage Calculator
Calculate MOSFET threshold voltage from device parameters
Volts (V) - typically -0.5 to 0.5 V
Volts (V) - typically 0.2-0.5 V
Note: This is a simplified calculation. Actual threshold voltage depends on many factors including oxide thickness, doping concentration, temperature, and body effect. Consult device physics textbooks for complete formulas.
How to Use This Calculator
Enter Flatband Voltage
Enter the flatband voltage (VFB) in volts. This accounts for work function differences and fixed oxide charges.
Enter Surface Potential
Enter the surface potential (|φ|) in volts. This is typically 0.2-0.5V for silicon devices.
Get Threshold Voltage
Click calculate to see the threshold voltage. This is a simplified estimate.
Formula
Vth = VFB + 2×|φ|
(Simplified formula)
Where:
- Vth = Threshold voltage (V)
- VFB = Flatband voltage (V)
- |φ| = Surface potential (V)
Complete Formula:
Vth = VFB + 2×|φ| + (√(2×εsi×q×Na×2×|φ|)) / Cox
This calculator uses a simplified version without the doping term.
Example:
VFB = -0.5 V, |φ| = 0.3 V
Vth = -0.5 + 2×0.3 = -0.5 + 0.6 = 0.1 V
About MOSFET Threshold Voltage Calculator
The MOSFET Threshold Voltage Calculator provides a simplified calculation of MOSFET threshold voltage (Vth). The threshold voltage is the minimum gate-source voltage needed to turn on the MOSFET and create a conducting channel. This is a fundamental parameter in MOSFET operation.
When to Use This Calculator
- Device Design: Estimate threshold voltage during MOSFET design
- Educational Purposes: Learn about MOSFET threshold voltage
- Circuit Analysis: Understand MOSFET switching characteristics
Why Use Our Calculator?
- ✅ Quick Estimates: Fast calculation for initial design
- ✅ Educational: Helps understand threshold voltage factors
- ✅ Free Tool: No registration required
Important Notes
Simplified Model: This calculator uses a simplified formula. Actual threshold voltage depends on many factors including:
- Oxide thickness (tox)
- Substrate doping concentration (Na or Nd)
- Body effect (substrate bias)
- Temperature
- Short-channel effects (for small devices)
Tips for Accurate Results
- This is a simplified estimate - actual values may vary
- Typical threshold voltages: 0.5-2V for enhancement mode
- Negative threshold = depletion mode MOSFET
- Consult device physics for complete calculations
- Check datasheet for actual measured values
Frequently Asked Questions
What is threshold voltage?
Threshold voltage (Vth) is the minimum gate-source voltage required to turn on a MOSFET and create a conducting channel between source and drain. Below this voltage, the MOSFET is off.
What is flatband voltage?
Flatband voltage (VFB) is the gate voltage at which there's no band bending in the semiconductor. It accounts for work function differences and fixed charges in the oxide.
What is surface potential?
Surface potential (φ) is the potential difference between the semiconductor surface and bulk. It's related to the energy needed to create an inversion layer.
Why is threshold voltage important?
Threshold voltage determines when a MOSFET turns on. It's critical for switching circuits, logic gates, and power electronics. Incorrect threshold voltage can cause circuit malfunction.