Emitter Resistance in Widlar Current Source Calculator

✖Threshold voltage of transistor is the minimum gate to source voltage that is needed to create a conducting path between the source and drain terminals.ⓘ Threshold Voltage [V_th]			+10% -10%
✖Output Current is the current the amplifier draws from the signal source.ⓘ Output Current [I_o]			+10% -10%
✖A reference current is just a stable source of current that does not fluctuate over temperature, supply voltages or loads.ⓘ Reference Current [I_ref]			+10% -10%

✖Emitter Resistance is the emitter-degeneration resistance of the emitter-base junction diode of a transistor.ⓘ Emitter Resistance in Widlar Current Source [R_e]

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Formula

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Emitter Resistance in Widlar Current Source

Formula

`"R"_{"e"} = ("V"_{"th"}/"I"_{"o"})*log10("I"_{"ref"}/"I"_{"o"})`

Example

`"0.909218kΩ"=("25V"/"5mA")*log10("7.60mA"/"5mA")`

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Emitter Resistance in Widlar Current Source Solution

STEP 0: Pre-Calculation Summary

Formula Used

Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current)
R_e = (V_th/I_o)*log10(I_ref/I_o)
This formula uses 1 Functions, 4 Variables

Functions Used

log10 - The common logarithm, also known as the base-10 logarithm or the decimal logarithm, is a mathematical function that is the inverse of the exponential function., log10(Number)

Variables Used

Emitter Resistance - (Measured in Ohm) - Emitter Resistance is the emitter-degeneration resistance of the emitter-base junction diode of a transistor.
Threshold Voltage - (Measured in Volt) - Threshold voltage of transistor is the minimum gate to source voltage that is needed to create a conducting path between the source and drain terminals.
Output Current - (Measured in Ampere) - Output Current is the current the amplifier draws from the signal source.
Reference Current - (Measured in Ampere) - A reference current is just a stable source of current that does not fluctuate over temperature, supply voltages or loads.

STEP 1: Convert Input(s) to Base Unit

Threshold Voltage: 25 Volt --> 25 Volt No Conversion Required
Output Current: 5 Milliampere --> 0.005 Ampere (Check conversion here)
Reference Current: 7.6 Milliampere --> 0.0076 Ampere (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

R_e = (V_th/I_o)*log10(I_ref/I_o) --> (25/0.005)*log10(0.0076/0.005)

Evaluating ... ...

R_e = 909.217939723863

STEP 3: Convert Result to Output's Unit

909.217939723863 Ohm -->0.909217939723863 Kilohm (Check conversion here)

FINAL ANSWER

0.909217939723863 ≈ 0.909218 Kilohm <-- Emitter Resistance

(Calculation completed in 00.004 seconds)

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< 10+ IC Amplifiers Calculators

Output Resistance of Widlar Current Source

Go Output Resistance of Widlar Current Source = (1+Transconductance)*((1/Emitter Resistance)+(1/Small-Signal Input Resistance b/w Base-Emitter))*Finite Output Resistance

Emitter Resistance in Widlar Current Source

Go Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current)

Output Current

Go Output Current given Reference Current = Reference Current*(Current in Transistor 2/Current in Transistor 1)

Output Resistance of Wilson MOS Mirror

Go Output Resistance = (Transconductance 3*Finite Output Resistance 3)*Finite Output Resistance 2

Output Resistance of Wilson Current Mirror

Go Output Resistance of Wilson Current Mirror = (Transistor Current Gain 1*Finite Output Resistance 3)/2

Reference Current of IC Amplifier

Go Reference Current = Output Current*(Aspect Ratio/Aspect Ratio 1)

Output Current of Wilson Current Mirror

Go Output Current = Reference Current*(1/(1+(2/Transistor Current Gain^2)))

Finite Output Resistance of IC Amplifier

Go Finite Output Resistance = Change in Output Voltage/Change in Current

Reference Current of Wilson Current Mirror

Go Reference Current = (1+2/Transistor Current Gain^2)*Output Current

Intrinsic Gain of IC Amplifier

Go Intrinsic Gain = 2*Early Voltage/Overdrive Voltage

Emitter Resistance in Widlar Current Source Formula

Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current)
R_e = (V_th/I_o)*log10(I_ref/I_o)

What is a Widlar Current Source?

A Widlar current source is a modification of the basic two-transistor current mirror that incorporates an emitter degeneration resistor for only the output transistor, enabling the current source to generate low currents using only moderate resistor values.

How to Calculate Emitter Resistance in Widlar Current Source?

Emitter Resistance in Widlar Current Source calculator uses Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current) to calculate the Emitter Resistance, The Emitter resistance in Widlar Current Source formula is defined as the opposition offered in the emitter region of the Widlar Current Source. Emitter Resistance is denoted by R_e symbol.

How to calculate Emitter Resistance in Widlar Current Source using this online calculator? To use this online calculator for Emitter Resistance in Widlar Current Source, enter Threshold Voltage (V_th), Output Current (I_o) & Reference Current (I_ref) and hit the calculate button. Here is how the Emitter Resistance in Widlar Current Source calculation can be explained with given input values -> 0.000909 = (25/0.005)*log10(0.0076/0.005).

FAQ

What is Emitter Resistance in Widlar Current Source?

The Emitter resistance in Widlar Current Source formula is defined as the opposition offered in the emitter region of the Widlar Current Source and is represented as R_e = (V_th/I_o)*log10(I_ref/I_o) or Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current). Threshold voltage of transistor is the minimum gate to source voltage that is needed to create a conducting path between the source and drain terminals, Output Current is the current the amplifier draws from the signal source & A reference current is just a stable source of current that does not fluctuate over temperature, supply voltages or loads.

How to calculate Emitter Resistance in Widlar Current Source?

The Emitter resistance in Widlar Current Source formula is defined as the opposition offered in the emitter region of the Widlar Current Source is calculated using Emitter Resistance = (Threshold Voltage/Output Current)*log10(Reference Current/Output Current). To calculate Emitter Resistance in Widlar Current Source, you need Threshold Voltage (V_th), Output Current (I_o) & Reference Current (I_ref). With our tool, you need to enter the respective value for Threshold Voltage, Output Current & Reference Current and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

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