Electronic Devices 2014
R1
T1. 1p
Zener diode: circuit symbol, current-voltage characteristic, regulating region, parametric voltage regulator
with the relation for resistance sizing.
T2. 1p
Simple non-inverting op-amp comparator with no feedback, different from zero threshold: circuit, VTC,
deduction of the threshold voltage, waveforms to illustrate the operation.
P1. 2.75p
Assume the ideal model for D1, D2.
a)0.5p Deduce the expression vO(vA, vB) and specify the
electric function of the circuit.
b)0.75p Find the values: vO; vD1; vD2 if vA= -8V and
vA
vB = 6V.
c)0.5p Find a suitable value for R so that for any
vA, vB in [-5V; 5V], the maximum forward current through
either of the diodes does not exceed 40mA.
d)1p For vA(t) = 7sinωt[V] and vB(t) = - 4sinωt[V], plot vO(t)
assuming: (1) D1, D2 – ideal; (2) D1, D2 – constant voltage drop model.
vD1
D1
vD2
D2
vO
vB R
vR
R2
P2. 2.75p
+VAl=16V
Consider OA – ideal, R1= 3kΩ, R2=15kΩ.
R1
a)0.75p Find the expression vO(vI) – for OpAmp in
AO
vI
active region. Find the vI range for that the OpAmp
work in active region.
-VAl=-16V
b)0.5p Plot the VTC vO(vI) for vI [-10V; 10V]. What
-8
is the application of the circuit?
c)0.25p What is the expression and value of the input
resistance Ri=?
c)0.5p Plot vO(t) for vI(t) = 3.5 sinωt[V].
d)0.75p Size the resistances R1 and R2 to obtain |vO/vI| =3. Plot the VTC vO(vI) of the new circuit.
P3. 2.5p
For T VTh  3V and   2mA/V2 .
a)0.5p What is the operating region of T for vI= 2.8V? Justify the
answer.
b)0.75p What is the operating region of T for vI=4V? Justify the
answer. Find the values of ID current and VDS voltage.
c)0.75p Find a value for vI, for that T work in extreme conduction
vI
region (cex). Prove that T work in desired region.
d)0.5p What is the logic function and the electric table of the
circuit, considering 0V - 0 logic, VDD  1 logic and vy – the output voltage?
RD
3K
T
vDS
VDD
10V
vy
vGS
iD
Electronic Devices 2014
R2
T1. 1p
Inverting op-amp amplifier: circuit, deduction of the differential voltage, deduction of the gain, input and
output resistances, VTC, range of the input voltage for the active region, waveforms to illustrate the operation
including the saturation of the amplifier.
T2. 1p
Logic inverter: circuit containing R and a controlled switch, truth table that include the state of the switch,
critical analysis, solutions to eliminate the disadvantages including truth tables with the states of the switches,
CMOS implementation with the operating table.
D
P1. 2.5p
Consider D – ideal, vC(0) = 0V, vI(t) = 8sint [V].
vD
a)1p Plot: vO(t); vD(t). Specify the state of the diode (on, off) on the vI
vo
C
vO(t) plot. What is the application of the circuit ?
b)0.5p Redraw vO(t) and vD(t) assuming the constant voltage drop
model for D (VD,on=0.7V).
c)1p Connect a load resistance RL at the output of the circuit and consider C=100F, =100. Find the
value of RL so that the output voltage ripple vO is smaller than 0.5V.
P2. 3p
R2
Assume OA – ideal, VRef= 5.5V R1= 3KΩ si R2= 9KΩ.
a) 0.5p What is the sign of circuit feedback and what is the
application of the circuit?
b) 1p Find the expressions and values of the following vI
parameters of the VTC: VThL, VThH, VOL and VOH. Draw
VTC vO(vI) of the circuit.
c) 0.75p Draw the waveforms of vO(t) for:
i) vI(t)=1.4sinωt[V], ii) vI(t)=14sinωt[V].
d) 0.75p Switch the places for vI and VRef. What is the new
application of the circuit and how the new VTC vO(vI) will
look like?
P3. 2.25p
Pentru T, β = 100 şi vBE,o n = 0.6V
a)0.5p What is the operating region of T for vI= 0.5V? Justify
the answer.
b)0.75p What is the operating region of T for vI=4V? Justify
the answer. Find the values of the IC current and VCE voltage.
c)0.75p Find a value for vI, for that T work in extreme
conduction region (cex). Prove that T work in desired region.
d) 0.25p For vI=8V, find the maximum value of RC, so that T is
in the extreme conduction region.
+VPs=15V
R1
OA
-VPS=-15V
vO
VRef
T
RC
1.5K
vCE
vI
vBE,on
RE
2K
iC
VAl=10V