Ohmic Region Drain Current of FET Calculator

Ohmic Region Drain Current of FET Formula:

\[ I_d(fet) = G_o(fet) \times \left( V_{ds}(fet) + \frac{3}{2} \times \frac{( \Psi_0(fet) + V_{ds}(fet) - V_{ds}(fet) )^{3/2} - ( \Psi_0(fet) + V_{ds}(fet) )^{3/2} }{ ( \Psi_0(fet) + V_{off}(fet) )^{1/2} } \right) \]

Channel Conductance FET (G₀):

Siemens

Drain Source Voltage FET (Vds):

Volt

Surface Potential FET (Ψ₀):

Volt

Pinch OFF Voltage (Voff):

Volt

Drain Current FET (Id):

Unit Converter ▲

Unit Converter ▼

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1. What is the Ohmic Region Drain Current of FET?

The Ohmic Region Drain Current of FET represents the current flowing through the drain junction of a Field-Effect Transistor when operating in the ohmic (linear) region. This region occurs when the drain-source voltage is small compared to the gate-source voltage minus the threshold voltage.

2. How Does the Calculator Work?

The calculator uses the Ohmic Region Drain Current formula:

Where:

\( I_d(fet) \) — Drain Current FET (Ampere)
\( G_o(fet) \) — Channel Conductance FET (Siemens)
\( V_{ds}(fet) \) — Drain Source Voltage FET (Volt)
\( \Psi_0(fet) \) — Surface Potential FET (Volt)
\( V_{off}(fet) \) — Pinch OFF Voltage (Volt)

Explanation: The equation calculates the drain current in the ohmic region by considering the channel conductance, drain-source voltage, surface potential, and pinch-off voltage of the FET.

3. Importance of Drain Current Calculation

Details: Accurate drain current calculation is crucial for designing and analyzing FET-based circuits, determining operating points, and ensuring proper transistor biasing in the ohmic region.

4. Using the Calculator

Tips: Enter all values in appropriate units. Channel conductance in Siemens, voltages in Volts. All values must be positive or zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the ohmic region in FET operation?
A: The ohmic region (also called linear region) is when the FET operates like a voltage-controlled resistor, with Vds < Vgs - Vth.

Q2: How does channel conductance affect drain current?
A: Channel conductance directly proportional to drain current - higher conductance means more current flows for the same voltage conditions.

Q3: What is the significance of surface potential?
A: Surface potential determines the energy band bending at the semiconductor surface and influences the carrier concentration in the channel.

Q4: When does pinch-off occur in a FET?
A: Pinch-off occurs when the channel is completely depleted of carriers, typically when Vds = Vgs - Vth, marking the boundary between ohmic and saturation regions.

Q5: Can this formula be used for all types of FETs?
A: This specific formula is typically used for MOSFETs and similar FET structures operating in the ohmic region. Different FET types may have variations in their current equations.