# Digital Electronics Homework #1 ```Digital Electronics Homework #1
Question #1:
Given τp = 1&micro;s, R = 1kΩ, Vf = 2V, Vr = -20V and VD = 0.65V at t = 0, find the
storage time in the diode in the figure below:
Question #2: Note the change from the original assignment!
Given If = 10mA, Ir = -20mA, and R = 500Ω, determine Tr &amp; Ts of the diode in
the above figure. The diode is characterized by Is = 2 x 10-15 A and Cj(av) = 5pF
when it is reverse-biased, and NA = 100ND = 1019cm-3. τp = 167ns.
Question #3:
Consider two diodes, one with Is1 = 10-14A and one with Is2 = 100Is1, connected
in series. Calculate the diode current, I, and the voltage across each diode if
the applied voltage is 1V.
Question #4:
The following are provide for a pn junction: NA = 1015cm-3, ND = 1017cm-3, and
the area is A = (40x40)&micro;m2. Calculate the following:
A. VD, Cjo, and Cj(av) as V changes from –10V to 0.5V.
B. W and Cj for V = -10V and V = 0.5V
Digital Electronics Homework #1 page 1
Question #5: Switching Diode:
Vd = 0.7V, VD(ON) = 0.7V, CT(0) = 2pF, τS = 10ns. Prior to t = t1, s is closed. At t
= t1, s is opened and left opened.
A. Determine ID at t &lt; t1.
B. Determine ID at the instant t = t1.
C. Plot ID versus time showing TS, the storage time, and TR, the recovery
time, until ID = 0.
D. Plot VD showing TS and TR.
E. Determine the storage time, TS.
F. What is the recovery time constant value = R*CT(av)?
G. What is the final stored charge in the diode after the switch is opened for