Small-Signal Diffusion Capacitance Calculator

✖A device constant value is defined once and can be referenced many times throughout a program.ⓘ Device Constant [𝛕_F]			+10% -10%
✖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%

✖Emitter-base capacitance is the capacitance between the emitter and the base.ⓘ Small-Signal Diffusion Capacitance [C_eb]

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Formula

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Small-Signal Diffusion Capacitance

Formula

`"C"_{"eb"} = "𝛕"_{"F"}*"G"_{"m"}`

Example

`"3440μF"="2s"*"1.72mS"`

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Small-Signal Diffusion Capacitance Solution

STEP 0: Pre-Calculation Summary

Formula Used

Emitter-Base Capacitance = Device Constant*Transconductance
C_eb = 𝛕_F*G_m
This formula uses 3 Variables

Variables Used

Emitter-Base Capacitance - (Measured in Farad) - Emitter-base capacitance is the capacitance between the emitter and the base.
Device Constant - (Measured in Second) - A device constant value is defined once and can be referenced many times throughout a program.
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.

STEP 1: Convert Input(s) to Base Unit

Device Constant: 2 Second --> 2 Second No Conversion Required
Transconductance: 1.72 Millisiemens --> 0.00172 Siemens (Check conversion here)

STEP 2: Evaluate Formula

Substituting Input Values in Formula

C_eb = 𝛕_F*G_m --> 2*0.00172

Evaluating ... ...

C_eb = 0.00344

STEP 3: Convert Result to Output's Unit

0.00344 Farad -->3440 Microfarad (Check conversion here)

FINAL ANSWER

3440 Microfarad <-- Emitter-Base Capacitance

(Calculation completed in 00.004 seconds)

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Home » Engineering » Electronics » BJT » Analog Electronics » Internal Capacitive Effects and High Frequency Model » Small-Signal Diffusion Capacitance

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Created by Payal Priya

Birsa Institute of Technology (BIT), Sindri

Payal Priya has created this Calculator and 600+ more calculators!

Verified by Urvi Rathod

Vishwakarma Government Engineering College (VGEC), Ahmedabad

Urvi Rathod has verified this Calculator and 1900+ more calculators!

< 11 Internal Capacitive Effects and High Frequency Model Calculators

Collector-Base Capacitance

Go Collector Base Capacitance = Emitter Base Junction Area*sqrt((Charge*Permittivity*Doping Density)/(2*(Built In Potential+Reverse Bias Junction)))

Collector-Base Junction Capacitance

Go Collector-Base Junction Capacitance = Collector-Base Junction Capacitance at 0 Voltage/(1+(Reverse-Bias Voltage/Built-In Voltage))^Grading Coefficient

Transition Frequency of BJT

Go Transition Frequency = Transconductance/(2*pi*(Emitter-Base Capacitance+Collector-Base Junction Capacitance))

Concentration of Electrons Injected from Emitter to Base

Go Concentration of e- Injected from Emitter to Base = Thermal Equilibrium Concentration*e^(Base-Emitter Voltage/Thermal Voltage)

Unity-Gain Bandwidth of BJT

Go Unity-Gain Bandwidth = Transconductance/(Emitter-Base Capacitance+Collector-Base Junction Capacitance)

Small-Signal Diffusion Capacitance of BJT

Go Emitter-Base Capacitance = Device Constant*(Collector Current/Threshold Voltage)

Thermal Equilibrium Concentration of Minority Charge Carrier

Go Thermal Equilibrium Concentration = ((Intrinsic Carrier Density)^2)/Doping Concentration of Base

Small-Signal Diffusion Capacitance

Go Emitter-Base Capacitance = Device Constant*Transconductance

Stored Electron Charge in Base of BJT

Go Stored Electron Charge = Device Constant*Collector Current

Transition Frequency of BJT given Device Constant

Go Transition Frequency = 1/(2*pi*Device Constant)

Base-Emitter Junction Capacitance

Go Base–Emitter Junction Capacitance = 2*Emitter-Base Capacitance

Small-Signal Diffusion Capacitance Formula

Emitter-Base Capacitance = Device Constant*Transconductance
C_eb = 𝛕_F*G_m

What is the difference between transition capacitance and diffusion capacitance?

Transition capacitance is basically the change of charge stored in the depletion region with respect to a change in voltage. And Diffusion capacitance is the capacitance caused due to movement of charge carriers between from anode to cathode in the forward-biased mode.

How to Calculate Small-Signal Diffusion Capacitance?

Small-Signal Diffusion Capacitance calculator uses Emitter-Base Capacitance = Device Constant*Transconductance to calculate the Emitter-Base Capacitance, The Small-signal diffusion capacitance formula is defined as the capacitance due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers from anode to cathode in the forward-bias mode of a diode or from emitter to base forward-biased junction for a transistor. Emitter-Base Capacitance is denoted by C_eb symbol.

How to calculate Small-Signal Diffusion Capacitance using this online calculator? To use this online calculator for Small-Signal Diffusion Capacitance, enter Device Constant (𝛕_F) & Transconductance (G_m) and hit the calculate button. Here is how the Small-Signal Diffusion Capacitance calculation can be explained with given input values -> 3.4E+9 = 2*0.00172.

FAQ

What is Small-Signal Diffusion Capacitance?

The Small-signal diffusion capacitance formula is defined as the capacitance due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers from anode to cathode in the forward-bias mode of a diode or from emitter to base forward-biased junction for a transistor and is represented as C_eb = 𝛕_F*G_m or Emitter-Base Capacitance = Device Constant*Transconductance. A device constant value is defined once and can be referenced many times throughout a program & 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.

How to calculate Small-Signal Diffusion Capacitance?

The Small-signal diffusion capacitance formula is defined as the capacitance due to transport of charge carriers between two terminals of a device, for example, the diffusion of carriers from anode to cathode in the forward-bias mode of a diode or from emitter to base forward-biased junction for a transistor is calculated using Emitter-Base Capacitance = Device Constant*Transconductance. To calculate Small-Signal Diffusion Capacitance, you need Device Constant (𝛕_F) & Transconductance (G_m). With our tool, you need to enter the respective value for Device Constant & Transconductance 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 Emitter-Base Capacitance?

In this formula, Emitter-Base Capacitance uses Device Constant & Transconductance. We can use 1 other way(s) to calculate the same, which is/are as follows -

Emitter-Base Capacitance = Device Constant*(Collector Current/Threshold Voltage)

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