Output Resistance of Widlar Current Source Calculator

Formula Used:

\[ R_{wcs} = (1 + g_m) \times \left( \frac{1}{R_e} + \frac{1}{R_{sbe}} \right) \times R_{fo} \]

Transconductance (g_m):

Siemens

Emitter Resistance (R_e):

Ohm

Small-Signal Input Resistance b/w Base-Emitter (R_sbe):

Ohm

Finite Output Resistance (R_fo):

Ohm

Output Resistance of Widlar Current Source (R_wcs):

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1. What is Output Resistance of Widlar Current Source?

Output Resistance of Widlar Current Source is the calculated resistance value obtained by adding the inverse values of individual resistors values. It represents the opposition to current flow in the Widlar current source configuration.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ R_{wcs} = (1 + g_m) \times \left( \frac{1}{R_e} + \frac{1}{R_{sbe}} \right) \times R_{fo} \]

Where:

\( R_{wcs} \) — Output Resistance of Widlar Current Source (Ohm)
\( g_m \) — Transconductance (Siemens)
\( R_e \) — Emitter Resistance (Ohm)
\( R_{sbe} \) — Small-Signal Input Resistance b/w Base-Emitter (Ohm)
\( R_{fo} \) — Finite Output Resistance (Ohm)

Explanation: The formula calculates the output resistance by considering the transconductance, emitter resistance, small-signal input resistance between base-emitter, and finite output resistance.

3. Importance of Output Resistance Calculation

Details: Accurate calculation of output resistance is crucial for designing stable current sources, analyzing circuit performance, and ensuring proper current regulation in electronic circuits.

4. Using the Calculator

Tips: Enter transconductance in Siemens, all resistances in Ohms. All values must be valid (resistances > 0, transconductance ≥ 0).

5. Frequently Asked Questions (FAQ)

Q1: What is transconductance in this context?
A: Transconductance is the change in the drain current divided by the small change in the gate/source voltage with a constant drain/source voltage.

Q2: What is emitter resistance?
A: Emitter Resistance is the emitter-degeneration resistance of the emitter-base junction diode of a transistor.

Q3: What is small-signal input resistance between base-emitter?
A: It is the opposition offered to the current passing through the base-emitter region under small-signal conditions.

Q4: What is finite output resistance?
A: The finite output resistance is the measure of the opposition to current flow, both static and dynamic, into the load network being connected that is internal to the electrical source.

Q5: When should this calculation be used?
A: This calculation is essential when designing or analyzing Widlar current sources in analog integrated circuits and other electronic applications requiring precise current regulation.