Test: Modelling The Diode Forward Characteristics - Electrical Engineering (EE) MCQ

All of the mentioned are different methods used to model a diode’s forward characteristics.

Voltage regulators are required in both of the situations mentioned.

Current I in the circuit = (10 – 2.1) / 1 or 7.9 mA
Incremental resistance of each diode is r_d = 25mV/7.9mA at room temperature or 3.2Ω
Total resistance of the diode connection = r = 9.6Ω
The series combination of R and r acts as a voltage divider, hence
▲V₀ = ±r/r+R or 9.5 mA or ± 0.5%.

When R_L is connected it draws approx. 2.1v/1000 A current or 2.1 mA. Hence the current in the diode decreases by approximately 2.1 mA. The voltage change across the diode is thus -2.1mA * 9.6 Ω or -20mA.

Thermal voltage at room temperature is 25mV and the current is 0.1mA. r_d = 25mV/0.1mA or 250 Ω.

 Normally a silicon diode has a voltage drop of 0.7V.

Graphical method uses equations obtained in the exponential method and then the Answer of these equations is obtained by plotting them on a graph.

 It is a required characteristic for small-ground operations.

Quiescent point is also called base point. It is due to this name that is also called Q–point.

 True value is obtained by the exponential method and therefore both of the statements are true.