Junction Capacitance Formula

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Junction capacitance is defined as the capacitance which forms in a PN junction diode under reverse bias. Check FAQs
Cj=(Aj2)2[Charge-e]kNBV-V1
Cj - Junction Capacitance?Aj - Junction Area?k - Constant Length Offset?NB - Doping Concentration of Base?V - Source Voltage?V1 - Source Voltage 1?[Charge-e] - Charge of electron?

Junction Capacitance Example

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With units
Only example

Here is how the Junction Capacitance equation looks like with Values.

Here is how the Junction Capacitance equation looks like with Units.

Here is how the Junction Capacitance equation looks like.

0.023Edit=(5401.3Edit2)21.6E-191.59Edit1E+28Edit120Edit-50Edit
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Junction Capacitance Solution

Follow our step by step solution on how to calculate Junction Capacitance?

FIRST Step Consider the formula
Cj=(Aj2)2[Charge-e]kNBV-V1
Next Step Substitute values of Variables
Cj=(5401.3µm²2)2[Charge-e]1.59μm1E+281/m³120V-50V
Next Step Substitute values of Constants
Cj=(5401.3µm²2)21.6E-19C1.59μm1E+281/m³120V-50V
Next Step Convert Units
Cj=(5.4E-92)21.6E-19C1.6E-6m1E+281/m³120V-50V
Next Step Prepare to Evaluate
Cj=(5.4E-92)21.6E-191.6E-61E+28120-50
Next Step Evaluate
Cj=2.30402951890085E-08F
Next Step Convert to Output's Unit
Cj=0.0230402951890085μF
LAST Step Rounding Answer
Cj=0.023μF

Junction Capacitance Formula Elements

Variables
Constants
Functions
Junction Capacitance
Junction capacitance is defined as the capacitance which forms in a PN junction diode under reverse bias.
Symbol: Cj
Measurement: CapacitanceUnit: μF
Note: Value should be greater than 0.
Junction Area
The Junction Area is the boundary or interface area between two types of semiconductor materials in a pn diode.
Symbol: Aj
Measurement: AreaUnit: µm²
Note: Value should be greater than 0.
Constant Length Offset
Constant Length Offset refers to a fixed or constant adjustment that is added to or subtracted from a measured or specified length.
Symbol: k
Measurement: LengthUnit: μm
Note: Value should be greater than 0.
Doping Concentration of Base
The Doping concentration of Base is the number of impurities added to the base.
Symbol: NB
Measurement: Carrier ConcentrationUnit: 1/m³
Note: Value should be greater than 0.
Source Voltage
Source Voltage is the difference in electric potential between two points, which is defined as the work needed per unit of charge to move a test charge between the two points.
Symbol: V
Measurement: Electric PotentialUnit: V
Note: Value can be positive or negative.
Source Voltage 1
Source Voltage 1 is the pressure from an electrical circuit's power source that pushes charged electrons (current) through a conducting loop, enabling them to do work such as illuminating a light.
Symbol: V1
Measurement: Electric PotentialUnit: V
Note: Value can be positive or negative.
Charge of electron
Charge of electron is a fundamental physical constant, representing the electric charge carried by an electron, which is the elementary particle with a negative electric charge.
Symbol: [Charge-e]
Value: 1.60217662E-19 C
sqrt
A square root function is a function that takes a non-negative number as an input and returns the square root of the given input number.
Syntax: sqrt(Number)

Other formulas in SSD Junction category

​Go N-Type Width
xno=|Q|AjNa[Charge-e]
​Go Junction Voltage
Vj=V-(Rse(p)+Rse(n))I
​Go Series Resistance in P-type
Rse(p)=(V-VjI)-Rse(n)
​Go Series Resistance in N-type
Rse(n)=(V-VjI)-Rse(p)

How to Evaluate Junction Capacitance?

Junction Capacitance evaluator uses Junction Capacitance = (Junction Area/2)*sqrt((2*[Charge-e]*Constant Length Offset*Doping Concentration of Base)/(Source Voltage-Source Voltage 1)) to evaluate the Junction Capacitance, The Junction Capacitance formula is defined as the capacitance which forms in a PN junction diode under reverse bias. In a normal capacitor, the two parallel conducting plates are electrodes which allow the conduction. Junction Capacitance is denoted by Cj symbol.

How to evaluate Junction Capacitance using this online evaluator? To use this online evaluator for Junction Capacitance, enter Junction Area (Aj), Constant Length Offset (k), Doping Concentration of Base (NB), Source Voltage (V) & Source Voltage 1 (V1) and hit the calculate button.

FAQs on Junction Capacitance

What is the formula to find Junction Capacitance?
The formula of Junction Capacitance is expressed as Junction Capacitance = (Junction Area/2)*sqrt((2*[Charge-e]*Constant Length Offset*Doping Concentration of Base)/(Source Voltage-Source Voltage 1)). Here is an example- 23040.3 = (5.4013E-09/2)*sqrt((2*[Charge-e]*1.59E-06*1E+28)/(120-50)).
How to calculate Junction Capacitance?
With Junction Area (Aj), Constant Length Offset (k), Doping Concentration of Base (NB), Source Voltage (V) & Source Voltage 1 (V1) we can find Junction Capacitance using the formula - Junction Capacitance = (Junction Area/2)*sqrt((2*[Charge-e]*Constant Length Offset*Doping Concentration of Base)/(Source Voltage-Source Voltage 1)). This formula also uses Charge of electron constant(s) and Square Root Function function(s).
Can the Junction Capacitance be negative?
No, the Junction Capacitance, measured in Capacitance cannot be negative.
Which unit is used to measure Junction Capacitance?
Junction Capacitance is usually measured using the Microfarad[μF] for Capacitance. Farad[μF], Kilofarad[μF], Millifarad[μF] are the few other units in which Junction Capacitance can be measured.
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