Output Resistance Of Emitter-Degenerated CE Amplifier Calculator

Formula Used:

\[ R_d = R_{out} + (g_{mp} \times R_{out}) \times \left(\frac{1}{R_e} + \frac{1}{R_{sm}}\right) \]

Finite Output Resistance (Rout):

Ohm

MOSFET Primary Transconductance (gmp):

Siemens

Emitter Resistance (Re):

Ohm

Small Signal Input Resistance (Rsm):

Ohm

Drain Resistance (Rd):

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1. What is Output Resistance of Emitter-Degenerated CE Amplifier?

The Output Resistance of an Emitter-Degenerated Common Emitter (CE) Amplifier represents the resistance seen at the output terminal of the amplifier. It is a crucial parameter that affects the amplifier's ability to drive loads and its overall voltage gain.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ R_d = R_{out} + (g_{mp} \times R_{out}) \times \left(\frac{1}{R_e} + \frac{1}{R_{sm}}\right) \]

Where:

\( R_d \) — Drain Resistance (Ohm)
\( R_{out} \) — Finite Output Resistance (Ohm)
\( g_{mp} \) — MOSFET Primary Transconductance (Siemens)
\( R_e \) — Emitter Resistance (Ohm)
\( R_{sm} \) — Small Signal Input Resistance (Ohm)

Explanation: This formula calculates the effective drain resistance by considering the finite output resistance enhanced by the product of transconductance and output resistance, multiplied by the parallel combination of emitter and small signal input resistances.

3. Importance of Drain Resistance Calculation

Details: Accurate calculation of drain resistance is essential for designing amplifier circuits with desired output characteristics, ensuring proper impedance matching, and optimizing voltage gain and bandwidth performance.

4. Using the Calculator

Tips: Enter all resistance values in Ohms and transconductance in Siemens. All values must be positive and non-zero for accurate calculation.

5. Frequently Asked Questions (FAQ)

Q1: What is emitter degeneration in CE amplifiers?
A: Emitter degeneration refers to adding a resistor in the emitter path of a common emitter amplifier to increase input impedance, improve linearity, and stabilize gain.

Q2: How does drain resistance affect amplifier performance?
A: Higher drain resistance typically results in higher voltage gain but may reduce bandwidth and output current capability.

Q3: What is the typical range for MOSFET transconductance?
A: MOSFET transconductance typically ranges from millisiemens to several siemens, depending on device size and operating conditions.

Q4: How does emitter resistance affect output resistance?
A: Increasing emitter resistance generally increases the output resistance of the amplifier due to negative feedback effects.

Q5: When should this calculation be used in circuit design?
A: This calculation is essential when designing common emitter amplifier stages with emitter degeneration for specific output impedance requirements.