MOSFET Calculator
Calculate MOSFET drain current and determine operating regimes (cutoff, triode, saturation)
Calculate MOSFET Parameters
Minimum gate voltage to turn on the MOSFET
MOSFET transconductance parameter
Voltage between gate and source terminals
Voltage between drain and source terminals
MOSFET Analysis Results
Current Equation: ID = 0 (Device OFF)
Regime Conditions: Vgs < VT
Operating Regime Analysis
Example: BS170 N-Channel MOSFET
Typical Parameters
Threshold Voltage (VT): 2.0 V
K Parameter: 0.05625 A/V²
Maximum Drain Current: 500 mA
Maximum VDS: 60 V
Saturation Regime Example
Given: VGS = 8.0 V, VDS = 10.0 V
Since VGS > VT and VDS > (VGS - VT):
ID = K(VGS - VT)² = 0.05625 × (8.0 - 2.0)²
ID = 2.025 A
MOSFET Operating Regimes
Cutoff
VGS < VT
Device is OFF
Triode
VGS ≥ VT, VDS ≤ (VGS - VT)
Variable resistor
Saturation
VGS ≥ VT, VDS > (VGS - VT)
Current source
MOSFET Applications
Digital logic circuits and processors
Power switching and motor drives
RF amplifiers and mixers
Voltage regulators and converters
Battery management systems
Mobile device power management
Understanding MOSFET Operation
What is a MOSFET?
MOSFET stands for Metal-Oxide-Semiconductor Field-Effect Transistor. It's a type of transistor that controls current flow through an electric field rather than current. MOSFETs are the fundamental building blocks of modern digital electronics.
Key Characteristics
- •High input impedance (gate is isolated)
- •Fast switching speeds
- •Low power consumption
- •Voltage-controlled device
Current Equations
Cutoff: ID = 0
Triode: ID = 2K[(VGS - VDS/2 - VT) × VDS]
Saturation: ID = K(VGS - VT)²
K: Transconductance parameter (A/V²)
VGS: Gate-to-source voltage
VDS: Drain-to-source voltage
VT: Threshold voltage
ID: Drain current
K Parameter: K = ½ × (W/L) × μN × Cox
where W/L is channel aspect ratio, μN is electron mobility, and Cox is oxide capacitance.