1. What is Common Emitter Amplifier Voltage Gain?

The common emitter amplifier is one of the most fundamental transistor amplifier configurations. The voltage gain (A_v) represents the ratio of output voltage to input voltage and is a key parameter in amplifier design and analysis.

2. How Does the Calculator Work?

The calculator uses the common emitter voltage gain formula:

Where:

• \( A_v \) — Voltage gain (dimensionless)
• \( R_C \) — Collector resistor (Ω)
• \( r_e \) — Emitter resistance (Ω)

Explanation: The negative sign indicates a 180° phase inversion between input and output signals, which is characteristic of common emitter amplifiers.

3. Importance of Voltage Gain Calculation

Details: Accurate voltage gain calculation is essential for designing amplifiers with desired amplification characteristics, ensuring proper signal levels, and predicting circuit behavior in electronic systems.

4. Using the Calculator

Tips: Enter collector resistor (R_C) and emitter resistance (r_e) in ohms (Ω). Both values must be positive and non-zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What does the negative sign in the gain indicate?
A: The negative sign indicates that the common emitter amplifier inverts the phase of the input signal by 180 degrees.

Q2: What are typical values for voltage gain in common emitter amplifiers?
A: Typical voltage gains range from 10 to 200, depending on the specific circuit design and component values.

Q3: How is emitter resistance (r_e) determined?
A: Emitter resistance is typically calculated as r_e = 25mV/I_E, where I_E is the emitter current in milliamps.

Q4: What factors affect the accuracy of this calculation?
A: This simplified formula assumes ideal transistor behavior and neglects effects like Early voltage, temperature variations, and parasitic capacitances.

Q5: When is this simplified gain formula most accurate?
A: This formula provides good accuracy for small-signal analysis at mid-frequencies where capacitive effects are negligible.