2. Electronics and Devices

Diode Devices — Quiz

Test your understanding of diode devices with 5 practice questions.

Practice Questions

Question 1

Given a silicon diode with saturation current $I_S=1\times10^{-12}\text{ A}$ and thermal voltage $V_T=25\text{ mV}$, calculate the forward current $I_D$ when the diode voltage $V_D=0.65\text{ V}$. Use the Shockley equation $I_D=I_S\left(e^{V_D/V_T}-1\right)$.

Question 2

Using the result $I_D\approx0.2\text{ A}$ at $V_D=0.65\text{ V}$, compute the small-signal dynamic resistance $r_d$ of the diode at this operating point. Use $r_d=V_T/I_D$.

Question 3

Which expression gives the approximate DC output voltage $V_{DC}$ of a full-wave bridge rectifier with sinusoidal input peak $V_m$ and diode forward drop $V_F$ on each conduction path?

Question 4

A varactor diode has junction capacitance following $C_j(V_R)=C_0\,(1+V_R/V_0)^{-m}$, where $C_0=100\text{ pF}$ at zero bias, $V_0=1\text{ V}$, and $m=0.5$. What is $C_j$ at reverse bias $V_R=3\text{ V}$?

Question 5

Which logic function is implemented by two ideal diodes with their anodes tied to inputs A and B, cathodes joined to the output node, and a pull-down resistor to ground?