In figure, a silicon diode is carrying a constant current

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In figure, a silicon diode is carrying a constant current of 1 mA. When the temperature of the diode is 20°C, V_D is found to be 700 mV. If the temperature raises to 40°C, V_D becomes approximately equal to—

1. 750 mV
2. 650 mV
3. 680 mV
4. 700 mV

Correct Option: B

We know that on increasing 1°C of temperature the cut-in-voltage V_r of the diode is approximately decreases by – 2·5 mV/°C.
So, net increase in temperature = (40 – 20) = 20°C
decrease in cut-in-voltage by = 700 mV – 20 × 2·5 mV = 650 mV (approximately)