Reference Current of BJT Current Mirror Calculator

Formula Used:

\[ I_{ref} = \frac{V_{DD} - V_{BE}}{R} \]

Reference Current (Iref):

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1. What is Reference Current of BJT Current Mirror?

The Reference Current in a BJT Current Mirror is a stable source of current that does not fluctuate over temperature, supply voltages or loads. It serves as the reference for mirroring current in other branches of the circuit.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ I_{ref} = \frac{V_{DD} - V_{BE}}{R} \]

Where:

\( I_{ref} \) — Reference Current (A)
\( V_{DD} \) — Supply Voltage (V)
\( V_{BE} \) — Base-Emitter Voltage (V)
\( R \) — Resistance (Ω)

Explanation: The formula calculates the reference current based on the voltage difference between supply voltage and base-emitter voltage, divided by the resistance value.

3. Importance of Reference Current Calculation

Details: Accurate reference current calculation is crucial for designing stable current mirror circuits, ensuring proper biasing of transistors, and maintaining consistent current replication in analog circuits.

4. Using the Calculator

Tips: Enter supply voltage in volts, base-emitter voltage in volts, and resistance in ohms. All values must be valid positive numbers with resistance > 0.

5. Frequently Asked Questions (FAQ)

Q1: What is a BJT Current Mirror?
A: A BJT Current Mirror is a circuit configuration that copies the current flowing through one active device by controlling the current in another active device, keeping the output current constant regardless of loading.

Q2: Why is reference current important?
A: The reference current determines the magnitude of the mirrored current and ensures stability and accuracy in current replication throughout the circuit.

Q3: What are typical values for VBE?
A: For silicon BJTs, VBE is typically around 0.6-0.7V, but it can vary depending on the transistor type and operating conditions.

Q4: What factors affect reference current stability?
A: Temperature variations, supply voltage fluctuations, and resistor tolerance can affect the stability of the reference current.

Q5: Can this calculator be used for MOSFET current mirrors?
A: No, this calculator is specifically designed for BJT current mirrors. MOSFET current mirrors use different formulas and parameters.