1. What is MOSFET Drain Current?

The drain current (I_d) in a MOSFET is the current that flows between the drain and source terminals when a voltage is applied to the gate. It's a fundamental parameter in MOSFET operation and circuit design.

2. How Does the Calculator Work?

The calculator uses the MOSFET drain current equation:

Where:

• \( I_d \) — Drain current (A)
• \( k \) — Transconductance parameter (A/V²)
• \( V_{gs} \) — Gate-source voltage (V)
• \( V_{th} \) — Threshold voltage (V)

Explanation: The equation shows that drain current depends on the square of the excess gate voltage (V_gs - V_th) and the device's transconductance parameter.

3. Importance of Drain Current Calculation

Details: Accurate drain current calculation is crucial for designing amplifiers, switches, and other electronic circuits using MOSFETs. It helps determine power consumption, gain, and switching characteristics.

4. Using the Calculator

Tips: Enter the transconductance parameter (k) in A/V², gate-source voltage (V_gs) in volts, and threshold voltage (V_th) in volts. All values must be valid (k > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the transconductance parameter (k)?
A: It's a device-specific parameter that depends on the MOSFET's physical characteristics, including channel dimensions and carrier mobility.

Q2: When is this equation valid?
A: This equation is valid when the MOSFET is in saturation region (V_ds > V_gs - V_th).

Q3: What are typical values for k?
A: For small-signal MOSFETs, k might be in the range of 0.001 to 0.1 A/V², while power MOSFETs can have much higher values.

Q4: How does temperature affect the calculation?
A: Temperature affects both threshold voltage and carrier mobility, which in turn affects drain current. This equation assumes constant temperature.

Q5: Can this be used for both NMOS and PMOS?
A: Yes, but for PMOS, voltages and current are negative, and the equation would use absolute values.