MOSFET Inversion Charge Calculator
Estimate the magnitude of the strong-inversion sheet charge from oxide capacitance and overdrive voltage using |Qinv| = Cox·Vov.
Description
Estimate the magnitude of the strong-inversion sheet charge from oxide capacitance and overdrive voltage using |Qinv| = Cox·Vov.
MOSFET Inversion Charge Calculator is a focused tool for the following task. Estimate the magnitude of the strong-inversion sheet charge from oxide capacitance and overdrive voltage using |Qinv| = Cox·Vov. It reports |Qinv| from the values you provide rather than inventing measurements, coefficients, or professional judgment that are not part of the input.
When to use MOSFET Inversion Charge
Use this semiconductor calculation for first-order device, material, fabrication, interconnect, packaging, or reliability estimates when every coefficient and unit convention is known.
- Cox (fF/µm²)
- Required number in fF/µm². Gate oxide capacitance per unit area. Must be greater than 0 fF/µm².
- Overdrive (V)
- Required number in V. Gate voltage above threshold. Must be greater than 0 V.
The cited overview of MOSFET supplies background for the terminology and domain context used by this tool.1
How MOSFET Inversion Charge works
Estimate the magnitude of the strong-inversion sheet charge from oxide capacitance and overdrive voltage using |Qinv| = Cox·Vov. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.
- |Qinv| (µC/cm²)
- Returned number in µC/cm². Magnitude of the ideal strong-inversion charge per unit gate area; the electron charge itself is negative for an n-channel MOSFET.
Limitations and assumptions
- Material composition, geometry, process history, temperature, electric field, bias, interfaces, parasitics, and fitted parameter ranges can invalidate a compact semiconductor model.
- Cox must be at least 5e-324.
- Overdrive must be at least 5e-324.
- Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.
Alternative or Complementary approaches
Compare the estimate with measured process data, current device documentation, and a higher-fidelity circuit, field, thermal, quantum, or TCAD model when the decision requires it.
References
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MOSFET — Wikipedia contributors
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