2020 Solution 02
2020 Solution 02
When the temperature of the diode is increased the voltage drop across the diode,
(a) Increases
(b) Decreases
(c) Unchanged
(d) 0.0
(e) Undefined
(a) Increases
(b) Decreases
(c) Unchanged
(d) 0.0
(e) Undefined
When temperature increases the reverse saturation current of the diode increases much more than the increase in thermal voltage (VT). This results in an increased current in the complete circuit. The drop across the resistor increases. Consequently the drop across the diode is smaller at the higher temperature.
Unfortunately the Shockley diode equation as popularly rendered is misleading, because it shows the explicit dependence of the thermal voltage (VT) on temperature T, but it does not show the dependence of the reverse saturation current on temperature.
Of course we all know from experience that diode drop and threshold voltages decrease with increasing temperature.