Code number ____________
Problem 4 (ECE core)
(Diode characteristics)
(a) Indicate on the pn junction figure (1) the polarity of
charges (+, -) that are uncovered by the diffusion in the
vicinity of the junction and (2) indicate the direction
(arrow) of the built-in electric-field. Assume Vbias = 0
(b) (1) Sketch a reasonable plot of I vs V chararacteristics
for the pn junction for bias over tha range –6.0V to +2.0V
and (2) identify typical magnitudes of current levels at
forward and reverse biases.
Code number ____________
Problem 4 (ECE core)
(Diode circuits)
For the diode circuit shown find values of voltages V3, V4
and current I2, using the constant voltage drop (CVD)
(0.7V drop) model of the diode.
Hint: Apply nodal analysis to nodes V3 and V4.
Code number ____________
Problem 4 (ECE core)
(biasing the transistor)
Assume  F = infinity and determine VB, VE, and VC (by inspection) for each of the following circuits: (Hint:
If  F = large then IB = very small). Resistances in k.
VB __________
VE __________
VC __________
VB __________
VE __________
VC __________
VB __________
VE __________
VC __________
Code number ____________
Problem 4 (ECE core)
(RLC resonant circuits)
For the RLC circuit shown find characteristic frequency f0, characteristic resistance R0, quality factor Q,
damping coefficient  and voltages as indicated. All voltages are defined relative to ground.
(a) f0 ________________
(b) R0 _______________
(c) Q _______________
(d)  ________________
(e) |V1(max)| ____________
(f) |V2 - V1|(max) ____________
(g) |V2(max)| ______________
Code number ____________
Problem 4 (ECE core)
For the Sallen-Key biquadratic circuit (shown) and the simulation results of its Bode magnitude plot,
determine
(a) Simulated (extract from Bode plot) and the analytical
values for quality factor Q,
(c) Analytical values for characteristic frequency f0 and
for (the expected) fpeak.
(e) On the Bode magnitude plot the 3dB levels to each
side of the peak are marked by the two cursors, which are
extended to the empty phase plot below. Trace the
expected phase plot for this circuit on the empty phase
plot. Be sure to identify the correct phase values at each
of the two 3dB levels
(Magnitude plot)
(Phase plot)