Pull Down Current In Linear Region Calculator

Formula Used:

\[ ID(linear) = \sum_{x=0}^{n} \left( \frac{\mu_n \cdot C_{ox}}{2} \right) \cdot \left( \frac{W}{L} \right) \cdot \left( 2 \cdot (V_{GS} - V_T) \cdot V_{out} - V_{out}^2 \right) \]

Number of Parallel Driver Transistors:

Electron Mobility:

m²/V·s

Oxide Capacitance:

Channel Width:

Channel Length:

Gate Source Voltage:

Threshold Voltage:

Output Voltage:

Linear Region Pull Down Current:

Unit Converter ▲

Unit Converter ▼

From:	To:

1. What is Linear Region Pull Down Current?

Linear Region Pull Down Current is the current through the resistor when a pull-down resistor is used with an N-channel MOSFET in linear mode. It represents the total current flowing through parallel driver transistors in the linear operating region of MOSFETs.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ ID(linear) = \sum_{x=0}^{n} \left( \frac{\mu_n \cdot C_{ox}}{2} \right) \cdot \left( \frac{W}{L} \right) \cdot \left( 2 \cdot (V_{GS} - V_T) \cdot V_{out} - V_{out}^2 \right) \]

Where:

\( n \) — Number of parallel driver transistors
\( \mu_n \) — Electron mobility (m²/V·s)
\( C_{ox} \) — Oxide capacitance (F)
\( W \) — Channel width (m)
\( L \) — Channel length (m)
\( V_{GS} \) — Gate source voltage (V)
\( V_T \) — Threshold voltage (V)
\( V_{out} \) — Output voltage (V)

Explanation: The formula calculates the sum of currents through all parallel driver transistors operating in the linear region, accounting for MOSFET characteristics and operating conditions.

3. Importance of Linear Region Current Calculation

Details: Accurate calculation of linear region current is crucial for MOSFET circuit design, power consumption analysis, thermal management, and ensuring proper switching characteristics in digital and analog circuits.

4. Using the Calculator

Tips: Enter all required parameters with appropriate units. Ensure positive values for physical quantities (n, μn, Cox, W, L, VGS). Threshold and output voltages can be positive or negative depending on circuit configuration.

5. Frequently Asked Questions (FAQ)

Q1: What is the linear region in MOSFET operation?
A: The linear region (also called ohmic or triode region) occurs when V_GS > V_T and V_DS < V_GS - V_T, where the MOSFET acts like a voltage-controlled resistor.

Q2: Why use multiple parallel driver transistors?
A: Parallel transistors increase current handling capacity, reduce on-resistance, and improve switching performance in power applications.

Q3: How does electron mobility affect the current?
A: Higher electron mobility allows electrons to move more easily through the channel, resulting in higher current flow for the same voltage conditions.

Q4: What factors influence threshold voltage?
A: Threshold voltage depends on oxide thickness, doping concentration, gate material, and temperature, among other factors.

Q5: When is this calculation most relevant?
A: This calculation is essential for analog circuit design, power MOSFET applications, and when designing circuits that operate MOSFETs in their linear region rather than saturation.