Common Mode Input Resistance of BJT Half-Circuit Calculator

✖Common emitter current gain is influenced by 2 factors: width of base region W, and relative dopings of base region and emitter region. Its range varies from 50-200.ⓘ Common Emitter Current Gain [β]			+10% -10%
✖Output resistance is the value of resistance of the network.ⓘ Output Resistance [R_o]			+10% -10%
✖Load Resistance is the external resistance or impedance that is connected to the output of a circuit or device, and it is used to extract power or signal from the circuit.ⓘ Load Resistance [R_L]			+10% -10%

✖Input Resistance is the resistance seen by the current source or voltage source which drives the circuit.ⓘ Common Mode Input Resistance of BJT Half-Circuit [R_in]

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Formula

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Common Mode Input Resistance of BJT Half-Circuit

Formula

`"R"_{"in"} = ("β"*"R"_{"o"})*((1+("R"_{"L"}/("β"*"R"_{"o"})))/(1+(("R"_{"L"}+(2*"R"_{"o"}))/"R"_{"o"})))`

Example

`"29.01699kΩ"=("65"*"2.12kΩ")*((1+("4kΩ"/("65"*"2.12kΩ")))/(1+(("4kΩ"+(2*"2.12kΩ"))/"2.12kΩ")))`

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Common Mode Input Resistance of BJT Half-Circuit Solution

STEP 0: Pre-Calculation Summary

Formula Used

Input Resistance = (Common Emitter Current Gain*Output Resistance)*((1+(Load Resistance/(Common Emitter Current Gain*Output Resistance)))/(1+((Load Resistance+(2*Output Resistance))/Output Resistance)))
R_in = (β*R_o)*((1+(R_L/(β*R_o)))/(1+((R_L+(2*R_o))/R_o)))
This formula uses 4 Variables

Variables Used

Input Resistance - (Measured in Ohm) - Input Resistance is the resistance seen by the current source or voltage source which drives the circuit.
Common Emitter Current Gain - Common emitter current gain is influenced by 2 factors: width of base region W, and relative dopings of base region and emitter region. Its range varies from 50-200.
Output Resistance - (Measured in Ohm) - Output resistance is the value of resistance of the network.
Load Resistance - (Measured in Ohm) - Load Resistance is the external resistance or impedance that is connected to the output of a circuit or device, and it is used to extract power or signal from the circuit.

STEP 1: Convert Input(s) to Base Unit

Common Emitter Current Gain: 65 --> No Conversion Required
Output Resistance: 2.12 Kilohm --> 2120 Ohm (Check conversion here)
Load Resistance: 4 Kilohm --> 4000 Ohm (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

R_in = (β*R_o)*((1+(R_L/(β*R_o)))/(1+((R_L+(2*R_o))/R_o))) --> (65*2120)*((1+(4000/(65*2120)))/(1+((4000+(2*2120))/2120)))

Evaluating ... ...

R_in = 29016.9884169884

STEP 3: Convert Result to Output's Unit

29016.9884169884 Ohm -->29.0169884169884 Kilohm (Check conversion here)

FINAL ANSWER

29.0169884169884 ≈ 29.01699 Kilohm <-- Input Resistance

(Calculation completed in 00.020 seconds)

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< 3 Common Mode Rejection Ratio (CMRR) Calculators

Common Mode Input Resistance of BJT Half-Circuit

Go Input Resistance = (Common Emitter Current Gain*Output Resistance)*((1+(Load Resistance/(Common Emitter Current Gain*Output Resistance)))/(1+((Load Resistance+(2*Output Resistance))/Output Resistance)))

Common Mode Rejection Ratio of BJT

Go Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance)

Common Mode Rejection Ratio

Go Common Mode Rejection Ratio = 20*log10(Differential Mode Gain/Common Mode Gain)

Common Mode Input Resistance of BJT Half-Circuit Formula

What is the difference between common mode and differential mode?

The common-mode refers to signals or noise that flow in the same direction in a pair of lines. The differential (normal) mode refers to signals or noise that flow in opposite directions in a pair of lines.

How to Calculate Common Mode Input Resistance of BJT Half-Circuit?

Common Mode Input Resistance of BJT Half-Circuit calculator uses Input Resistance = (Common Emitter Current Gain*Output Resistance)*((1+(Load Resistance/(Common Emitter Current Gain*Output Resistance)))/(1+((Load Resistance+(2*Output Resistance))/Output Resistance))) to calculate the Input Resistance, The Common mode input resistance of BJT half-circuit formula is defined as a metric used to quantify the ability of the device to reject common-mode signals, i.e. those that appear simultaneously and in phase on both inputs. Input Resistance is denoted by R_in symbol.

How to calculate Common Mode Input Resistance of BJT Half-Circuit using this online calculator? To use this online calculator for Common Mode Input Resistance of BJT Half-Circuit, enter Common Emitter Current Gain (β), Output Resistance (R_o) & Load Resistance (R_L) and hit the calculate button. Here is how the Common Mode Input Resistance of BJT Half-Circuit calculation can be explained with given input values -> 0.029017 = (65*2120)*((1+(4000/(65*2120)))/(1+((4000+(2*2120))/2120))).

FAQ

What is Common Mode Input Resistance of BJT Half-Circuit?

The Common mode input resistance of BJT half-circuit formula is defined as a metric used to quantify the ability of the device to reject common-mode signals, i.e. those that appear simultaneously and in phase on both inputs and is represented as R_in = (β*R_o)*((1+(R_L/(β*R_o)))/(1+((R_L+(2*R_o))/R_o))) or Input Resistance = (Common Emitter Current Gain*Output Resistance)*((1+(Load Resistance/(Common Emitter Current Gain*Output Resistance)))/(1+((Load Resistance+(2*Output Resistance))/Output Resistance))). Common emitter current gain is influenced by 2 factors: width of base region W, and relative dopings of base region and emitter region. Its range varies from 50-200, Output resistance is the value of resistance of the network & Load Resistance is the external resistance or impedance that is connected to the output of a circuit or device, and it is used to extract power or signal from the circuit.

How to calculate Common Mode Input Resistance of BJT Half-Circuit?

The Common mode input resistance of BJT half-circuit formula is defined as a metric used to quantify the ability of the device to reject common-mode signals, i.e. those that appear simultaneously and in phase on both inputs is calculated using Input Resistance = (Common Emitter Current Gain*Output Resistance)*((1+(Load Resistance/(Common Emitter Current Gain*Output Resistance)))/(1+((Load Resistance+(2*Output Resistance))/Output Resistance))). To calculate Common Mode Input Resistance of BJT Half-Circuit, you need Common Emitter Current Gain (β), Output Resistance (R_o) & Load Resistance (R_L). With our tool, you need to enter the respective value for Common Emitter Current Gain, Output Resistance & Load Resistance 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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