Output Current of Small Signal Calculator

Formula Used:

\[ I_{out} = (g_m \times V_c) \times \left( \frac{R_d}{R_L + R_d} \right) \]

Transconductance (g_m):

Siemens

Critical Voltage (V_c):

Volt

Drain Resistance (R_d):

Ohm

Load Resistance (R_L):

Ohm

Output Current (I_out):

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1. What is the Output Current Formula?

The Output Current formula calculates the current flowing through the drain terminal of a MOSFET when a voltage is applied at the gate terminal. This formula is essential for analyzing small signal amplifier circuits.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ I_{out} = (g_m \times V_c) \times \left( \frac{R_d}{R_L + R_d} \right) \]

Where:

\( I_{out} \) — Output Current (Ampere)
\( g_m \) — Transconductance (Siemens)
\( V_c \) — Critical Voltage (Volt)
\( R_d \) — Drain Resistance (Ohm)
\( R_L \) — Load Resistance (Ohm)

Explanation: The formula calculates the output current by multiplying the transconductance and critical voltage, then scaling it by the voltage divider ratio formed by the drain and load resistances.

3. Importance of Output Current Calculation

Details: Accurate output current calculation is crucial for designing and analyzing MOSFET amplifier circuits, determining gain, and ensuring proper circuit operation in small signal applications.

4. Using the Calculator

Tips: Enter transconductance in Siemens, critical voltage in Volts, and both resistances in Ohms. All values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is transconductance in MOSFETs?
A: Transconductance (g_m) is the ratio of the change in drain current to the change in gate-source voltage, representing the MOSFET's amplification capability.

Q2: What is critical voltage in this context?
A: Critical voltage refers to the minimum gate-source voltage required to create a conducting channel between the source and drain terminals.

Q3: How does load resistance affect output current?
A: Higher load resistance decreases the output current due to the voltage divider effect between drain resistance and load resistance.

Q4: Can this formula be used for large signal analysis?
A: This specific formula is designed for small signal analysis where the MOSFET operates in its linear region.

Q5: What are typical values for these parameters?
A: Transconductance typically ranges from 0.001 to 0.1 S, critical voltage from 0.5 to 5 V, and resistances from 100 Ω to 100 kΩ, depending on the specific MOSFET and circuit design.