Common Mode Rejection Ratio of BJT Calculator

✖Transconductance is the ratio of the change in current at the output terminal to the change in the voltage at the input terminal of an active device.ⓘ Transconductance [G_m]			+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%
✖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%

✖Common Mode Rejection Ratio indicates how much of the common-mode signal will appear in your measurement.ⓘ Common Mode Rejection Ratio of BJT [CMRR]

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Common Mode Rejection Ratio of BJT Solution

STEP 0: Pre-Calculation Summary

Formula Used

Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance)
CMRR = (2*G_m*R_o)/(ΔR_c/R_c)
This formula uses 5 Variables

Variables Used

Common Mode Rejection Ratio - (Measured in Decibel) - Common Mode Rejection Ratio indicates how much of the common-mode signal will appear in your measurement.
Transconductance - (Measured in Siemens) - Transconductance is the ratio of the change in current at the output terminal to the change in the voltage at the input terminal of an active device.
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.
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".

STEP 1: Convert Input(s) to Base Unit

Transconductance: 1.72 Millisiemens --> 0.00172 Siemens (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)
Collector Resistance: 3.75 Kilohm --> 3750 Ohm (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

CMRR = (2*G_m*R_o)/(ΔR_c/R_c) --> (2*0.00172*2120)/(2400/3750)

Evaluating ... ...

CMRR = 11.395

STEP 3: Convert Result to Output's Unit

11.395 Decibel --> No Conversion Required

FINAL ANSWER

11.395 Decibel <-- Common Mode Rejection Ratio

(Calculation completed in 00.004 seconds)

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Created by Payal Priya

Birsa Institute of Technology (BIT), Sindri

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< Common Mode Rejection Ratio (CMRR) Calculators

Common Mode Input Resistance of BJT Half-Circuit

LaTeX 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

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

Common Mode Rejection Ratio

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

Common Mode Rejection Ratio of BJT Formula

LaTeX Go

Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance)
CMRR = (2*G_m*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 Rejection Ratio of BJT?

Common Mode Rejection Ratio of BJT calculator uses Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance) to calculate the Common Mode Rejection Ratio, The Common mode rejection ratio of BJT 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. Common Mode Rejection Ratio is denoted by CMRR symbol.

How to calculate Common Mode Rejection Ratio of BJT using this online calculator? To use this online calculator for Common Mode Rejection Ratio of BJT, enter Transconductance (G_m), Output Resistance (R_o), Change in Collector Resistance (ΔR_c) & Collector Resistance (R_c) and hit the calculate button. Here is how the Common Mode Rejection Ratio of BJT calculation can be explained with given input values -> 11.395 = (2*0.00172*2120)/(2400/3750).

FAQ

What is Common Mode Rejection Ratio of BJT?

The Common mode rejection ratio of BJT 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 CMRR = (2*G_m*R_o)/(ΔR_c/R_c) or Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance). Transconductance is the ratio of the change in current at the output terminal to the change in the voltage at the input terminal of an active device, 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 & 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".

How to calculate Common Mode Rejection Ratio of BJT?

The Common mode rejection ratio of BJT 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 Common Mode Rejection Ratio = (2*Transconductance*Output Resistance)/(Change in Collector Resistance/Collector Resistance). To calculate Common Mode Rejection Ratio of BJT, you need Transconductance (G_m), Output Resistance (R_o), Change in Collector Resistance (ΔR_c) & Collector Resistance (R_c). With our tool, you need to enter the respective value for Transconductance, Output Resistance, Change in Collector Resistance & Collector Resistance and hit the calculate button. You can also select the units (if any) for Input(s) and the Output as well.

How many ways are there to calculate Common Mode Rejection Ratio?

In this formula, Common Mode Rejection Ratio uses Transconductance, Output Resistance, Change in Collector Resistance & Collector Resistance. We can use 1 other way(s) to calculate the same, which is/are as follows -

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

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