The voltage across a silicon diode at room temperature (300 K) is 0.7 Volts when 2 mA current flows through it. If the voltage increases to 0.75 V, calculate the diode current (assume VT = 26 mV).

Question

The voltage across a silicon diode at room temperature (300 K) is 0.7 Volts when 2 mA current flows through it. If the voltage increases to 0.75 V, calculate the diode current (assume [latex]V_{T}[/latex] = 26 mV).

Accepted Answer

Given data

Room temperature = 300 K

Voltage across a silicon diode, [latex]V_{D1}[/latex] = 0.7 V

Current through the diode [latex]I_{D1}[/latex] = 2 mA

When the voltage increases to 0.75 V, [latex]V_{D2}[/latex], then

[latex]\frac{I_{D2} }{I_{D1}}=\frac{I_{o} (e^{V_{D2}/V_{T}\eta } -1)}{I_{o} (e^{V_{D1}/V_{T}\eta } -1)}=\frac{e^{0.75/26 imes 10^{-3} } imes 2-1}{e^{0.7/26 imes 10^{-3} } imes 2-1}=2.615 [/latex]

Therefore, [latex]I_{D2} = 2.615 × I_{D1}[/latex]

[latex]= 2.615 × 2 × 10^{ – 3} = 5.23 mA[/latex]

Question 4.22: The voltage across a silicon diode at room temperature (300 ...

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