Common Mode Gain of BJT Calculator

✖Collector Resistance (Rc)helps to set the transistor at the "operating point" of the amplifier. The purpose of the emitter resistor Re is to prevent "thermal runaway".ⓘ Collector Resistance [R_c]			+10% -10%
✖Output resistance is the value of resistance of the network.ⓘ Output Resistance [R_o]			+10% -10%
✖Change in collector resistance is the increment or decrement in resistance passing through the collector region.ⓘ Change in Collector Resistance [ΔR_c]			+10% -10%

✖Common Mode Gain is typically much smaller than the differential gain. Acm is the gain given to a voltage that appears on both input terminals with respect to the ground.ⓘ Common Mode Gain of BJT [A_cm]

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Formula

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Common Mode Gain of BJT

Formula

`"A"_{"cm"} = -("R"_{"c"}/(2*"R"_{"o"}))*("ΔR"_{"c"}/"R"_{"c"})`

Example

`"-0.566038dB"=-("3.75kΩ"/(2*"2.12kΩ"))*("2.4kΩ"/"3.75kΩ")`

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Common Mode Gain of BJT Solution

STEP 0: Pre-Calculation Summary

Formula Used

Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance)
A_cm = -(R_c/(2*R_o))*(ΔR_c/R_c)
This formula uses 4 Variables

Variables Used

Common Mode Gain - (Measured in Decibel) - Common Mode Gain is typically much smaller than the differential gain. Acm is the gain given to a voltage that appears on both input terminals with respect to the ground.
Collector Resistance - (Measured in Ohm) - Collector Resistance (Rc)helps to set the transistor at the "operating point" of the amplifier. The purpose of the emitter resistor Re is to prevent "thermal runaway".
Output Resistance - (Measured in Ohm) - Output resistance is the value of resistance of the network.
Change in Collector Resistance - (Measured in Ohm) - Change in collector resistance is the increment or decrement in resistance passing through the collector region.

STEP 1: Convert Input(s) to Base Unit

Collector Resistance: 3.75 Kilohm --> 3750 Ohm (Check conversion here)
Output Resistance: 2.12 Kilohm --> 2120 Ohm (Check conversion here)
Change in Collector Resistance: 2.4 Kilohm --> 2400 Ohm (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

A_cm = -(R_c/(2*R_o))*(ΔR_c/R_c) --> -(3750/(2*2120))*(2400/3750)

Evaluating ... ...

A_cm = -0.566037735849057

STEP 3: Convert Result to Output's Unit

-0.566037735849057 Decibel --> No Conversion Required

FINAL ANSWER

-0.566037735849057 ≈ -0.566038 Decibel <-- Common Mode Gain

(Calculation completed in 00.004 seconds)

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< 16 Amplification Factor/Gain Calculators

Amplification Factor of BJT

Go BJT Amplification Factor = (Collector Current/Threshold Voltage)*((Positive DC Voltage+Collector-Emitter Voltage)/Collector Current)

Overall Voltage Gain of Amplifier when Load Resistance is Connected to Output

Go Voltage Gain = Common-Base Current Gain*(1/Collector Resistance+1/Load Resistance)^-1/(Signal Resistance+Emitter Resistance)

Overall Voltage Gain of Buffer Amplifier given Load Resistance

Go Voltage Gain = Load Resistance/(Load Resistance+Emitter Resistance+Signal Resistance/(Common Emitter Current Gain+1))

Overall Voltage Gain given Load Resistance of BJT

Go Voltage Gain = -Transconductance*((Collector Resistance*Load Resistance)/(Collector Resistance+Load Resistance))

Common Mode Gain of BJT

Go Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance)

Total Power Dissipated in BJT

Go Power = Collector-Emitter Voltage*Collector Current+Base-Emitter Voltage*Base Current

Voltage Gain given all Voltages

Go Voltage Gain = -(Supply Voltage-Collector-Emitter Voltage)/Thermal Voltage

Voltage Gain given Collector Current

Go Voltage Gain = -(Collector Current/Thermal Voltage)*Collector Resistance

Total Power Supplied in BJT

Go Power = Supply Voltage*(Collector Current+Input Current)

Common-Base Current Gain

Go Common-Base Current Gain = Common Emitter Current Gain/(Common Emitter Current Gain+1)

Common-Emitter Current Gain using Common-Base Current Gain

Go Common Emitter Current Gain = Common-Base Current Gain/(1-Common-Base Current Gain)

Open Circuit Voltage Gain given Open Circuit Transresistance

Go Open Circuit Voltage Gain = Open Circuit Transresistance/Input Resistance

Forced Common-Emitter Current Gain

Go Forced Common-Emitter Current Gain = Collector Current/Base Current

Voltage Gain given Transconductance and Collector Resistance

Go Voltage Gain = -Transconductance*Collector Resistance

Intrinsic Gain of BJT

Go Intrinsic Gain = Early Voltage/Thermal Voltage

Short-Circuit Current Gain

Go Current Gain = Output Current/Input Current

Common Mode Gain of BJT Formula

Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance)
A_cm = -(R_c/(2*R_o))*(ΔR_c/R_c)

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 Gain of BJT?

Common Mode Gain of BJT calculator uses Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance) to calculate the Common Mode Gain, The Common mode gain of BJT formula is defined as the common mode gain of a BJT amplifier is a measure of how much the output voltage changes when there is a change in the common-mode input voltage. It is typically expressed as a ratio or a percentage. Common Mode Gain is denoted by A_cm symbol.

How to calculate Common Mode Gain of BJT using this online calculator? To use this online calculator for Common Mode Gain of BJT, enter Collector Resistance (R_c), Output Resistance (R_o) & Change in Collector Resistance (ΔR_c) and hit the calculate button. Here is how the Common Mode Gain of BJT calculation can be explained with given input values -> -0.566038 = -(3750/(2*2120))*(2400/3750).

FAQ

What is Common Mode Gain of BJT?

The Common mode gain of BJT formula is defined as the common mode gain of a BJT amplifier is a measure of how much the output voltage changes when there is a change in the common-mode input voltage. It is typically expressed as a ratio or a percentage and is represented as A_cm = -(R_c/(2*R_o))*(ΔR_c/R_c) or Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance). Collector Resistance (Rc)helps to set the transistor at the "operating point" of the amplifier. The purpose of the emitter resistor Re is to prevent "thermal runaway", Output resistance is the value of resistance of the network & Change in collector resistance is the increment or decrement in resistance passing through the collector region.

How to calculate Common Mode Gain of BJT?

The Common mode gain of BJT formula is defined as the common mode gain of a BJT amplifier is a measure of how much the output voltage changes when there is a change in the common-mode input voltage. It is typically expressed as a ratio or a percentage is calculated using Common Mode Gain = -(Collector Resistance/(2*Output Resistance))*(Change in Collector Resistance/Collector Resistance). To calculate Common Mode Gain of BJT, you need Collector Resistance (R_c), Output Resistance (R_o) & Change in Collector Resistance (ΔR_c). With our tool, you need to enter the respective value for Collector Resistance, Output Resistance & Change in Collector 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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