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ECE Fun II Test 2 Review
ECE Fun II
Test 2
Topics
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LTI systems
Input/output in time and frequency domains
o Sinusoids, periodic, and transient functions
Impulse Response
Delta function properties
o Convolution
o h(ω)
Diodes
Ideal Model
o Constant forward voltage drop model
o Switch model
o Exponential model
o Use of diodes with opamps.
MOSFETs
Basic operation, terminals and polarities
o Biasing
o Small signal model
o Transconductance
 Assumed linear range
o Common source amplifier
The impulse response is the output of a system when the input is a
unit delta function.
True
False
The impulse response is the output of a system when the input is a
unit delta function.
True
False
Whether or not the system is linear, the impulse tells us everything we
need to know about the system.
True
False
Whether or not the system is linear, the impulse tells us everything we
need to know about the system.
True
False
If the impulse response to the system is h(t), then the output of the
system is the convolution of h(t) and the input x(t) except when the
initial conditions are zero (at rest).
True
False
If the impulse response to the system is h(t), then the output of the
system is the convolution of h(t) and the input x(t) except when the
initial conditions are zero (at rest).
True
False
In convolution, when either function is multiplied by a step function u(t), the
step function can be removed from the convolution integral by changing the
limits of integration
True
False
In convolution, when either function is multiplied by a step function u(t), the
step function can be removed from the convolution integral by changing the
limits of integration
True
False
You are given the following circuit in the figure. Assume that the op amp has infinite
gain, unlimited bandwidth, but is bounded in output by VCC and VEE, where VCC is
the most positive voltage in the system and VEE is the most negative voltage in the
system.
A
C
B
D
You are given the following circuit in the figure. Assume that the op amp has infinite
gain, unlimited bandwidth, but is bounded in output by VCC and VEE, where VCC is
the most positive voltage in the system and VEE is the most negative voltage in the
system.
A
C
B
D
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A system with input x(t) and output y(t)= x(0) + x(t).
Linear?
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A system with input x(t) and output y(t)= x(0) + x(t).
Linear? A
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A system with input x(t) and output y(t)= x(0) + x(t).
Linear? A
Time invariant? B
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 An ordinary light switch, where the input is the force
with which the switch is pressed, and the output is the
amount of light produced.
Linear?
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 An ordinary light switch, where the input is the force
with which the switch is pressed, and the output is the
amount of light produced.
Linear? B
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 An ordinary light switch, where the input is the force
with which the switch is pressed, and the output is the
amount of light produced.
Linear? B
Time invariant? A
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A second order passive RLC circuit driven by an input
voltage Vin(t) and measuring as output the voltage drop
across the capacitor. Assume the components have zero
energy stored before the input is applied.
Linear?
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A second order passive RLC circuit driven by an input
voltage Vin(t) and measuring as output the voltage drop
across the capacitor. Assume the components have zero
energy stored before the input is applied.
Linear? A
Time invariant?
For the system described below determine if it is linear and time invariant.
Rubric:
A: Yes
B: No
C: Cannot tell
 A second order passive RLC circuit driven by an input
voltage Vin(t) and measuring as output the voltage drop
across the capacitor. Assume the components have zero
energy stored before the input is applied.
Linear? A
Time invariant? A
If V1 is 4.7 Volts and R1 is 4k Ohms, using the constant forward voltage
model with Vdiode=0.7 V, the voltage across R1 is:
A. 0 Volts
B. 4.7 Volts
C. 4.0 Volts
D. Not enough information to calculate it
If V1 is 4.7 Volts and R1 is 4k Ohms, using the constant forward voltage
model with Vdiode=0.7 V, the voltage across R1 is:
A. 0 Volts
B. 4.7 Volts
C. 4.0 Volts
D. Not enough information to calculate it
If V1 is 0.5 Volts and R1 is 4k Ohms, using the constant forward voltage
model with Vdiode=0.7 V, the voltage across R1 is:
A. 4 Volts
B. 0.5 Volts
C. 0 Volts
D. 0.2 Volts
If V1 is 0.5 Volts and R1 is 4k Ohms, using the constant forward voltage
model with Vdiode=0.7 V, the voltage across R1 is:
A. 4 Volts
B. 0.5 Volts
C. 0 Volts
D. 0.2 Volts
Given the following circuit values: R1=R4=1K, R2=R3=3K, V1=12V. Assuming
the Constant Forward Voltage Drop model, (CFVD, VF=0.7V) which of the
following is true?
A. The diode current is approximately 0.5 mA.
B. The diode current is approximately 1.0 mA
C. The diode current is approximately 6.0 mA
D. None of the other choices is correct.
Given the following circuit values: R1=R4=1K, R2=R3=3K, V1=12V. Assuming
the Constant Forward Voltage Drop model, (CFVD, VF=0.7V) which of the
following is true?
A. The diode current is approximately 0.5 mA.
B. The diode current is approximately 1.0 mA
C. The diode current is approximately 6.0 mA
D. None of the other choices is correct.
If R2=R3=1K, R4=R1=1000K, V1=10.7 V, and assuming the CFVD model,
which of the following is true?
A. The diode current is approximately 5 mA.
B. The diode current is approximately 2.5 mA.
C. The diode is not conducting.
D. None of the other choices is correct.
If R2=R3=1K, R4=R1=1000K, V1=10.7 V, and assuming the CFVD model,
which of the following is true?
A. The diode current is approximately 5 mA.
B. The diode current is approximately 2.5 mA.
C. The diode is not conducting.
D. None of the other choices is correct.
Which of the following best describes the display?
A. The system settings for the vertical scale should be increased, i.e.
more volts per division.
B. The system settings for the horizontal scale should be decreased,
i.e. less time per division .
C. Both the vertical and horizontal scales are set incorrectly.
D. None of the other choices is correct.
Which of the following best describes the display?
A. The system settings for the vertical scale should be increased, i.e.
more volts per division.
B. The system settings for the horizontal scale should be decreased,
i.e. less time per division .
C. Both the vertical and horizontal scales are set incorrectly.
D. None of the other choices is correct.
If the setting of the signal generator is 2 VP-P and the
oscilloscope displays a 0.1 V amplitude signal, which of the
following is true.
A. The probe setting is at 10X but the VB setting is at 1X .
B. The signal generator is set at 10X, and the probe is set to 1X.
C. The signal generator is set to 10X and the probe is set to 10X.
D. None of the other choices is correct.
If the setting of the signal generator is 2 VP-P and the
oscilloscope displays a 0.1 V amplitude signal, which of the
following is true.
A. The probe setting is at 10X but the VB setting is at 1X .
B. The signal generator is set at 10X, and the probe is set to 1X.
C. The signal generator is set to 10X and the probe is set to 10X.
D. None of the other choices is correct.
Assume that the circuit is operating in the saturated region for Q1.
Which of the following is true?
A. If the value of RD is reduced by a factor of 2, the voltage gain
will go down, approximately by 2 but the operating region will
not change.
B. If the value of RD is increased by a factor of 2 the voltage gain
will increase by 2 and the operating region will not change.
C. If R1 is decreased the operating region will not change.
D. None of the other choices is true.
Assume that the circuit is operating in the saturated region for Q1.
Which of the following is true?
A. If the value of RD is reduced by a factor of 2, the voltage gain
will go down, approximately by 2 but the operating region will
not change.
B. If the value of RD is increased by a factor of 2 the voltage gain
will increase by 2 and the operating region will not change.
C. If R1 is decreased the operating region will not change.
D. None of the other choices is true.
Assume that RD is 2K, RL is 100K and the overall voltage gain is 3 with a gm of
0.05S. The frequency of V2 is 100KHZ and the circuit is operating in mid-band and
the small signal model applies. Which of the following is true?
A. The voltage gain will be relatively stable over significant changes in the
values of the circuit parameters for Q1.
B. RS affects the value of the low-pass breakpoint associated with C2.
C. If R1 is decreased, the value of the gain will decrease, but the breakpoint
frequencies for the overall circuit will not be affected.
D. None of the other answers is correct.
Assume that RD is 2K, RL is 100K and the overall voltage gain is 3 with a gm of
0.05S. The frequency of V2 is 100KHZ and the circuit is operating in mid-band and
the small signal model applies. Which of the following is true?
A. The voltage gain will be relatively stable over significant changes in the
values of the circuit parameters for Q1.
B. RS affects the value of the low-pass breakpoint associated with C2.
C. If R1 is decreased, the value of the gain will decrease, but the breakpoint
frequencies for the overall circuit will not be affected.
D. None of the other answers is correct.
Using the values from the previous question, assume that a 10000 µF capacitor is
placed in parallel with RS. Which of the following is true?
A. The voltage gain would increase to approximately 100, but the input signal
would have to be reduced to stay in the range of operation for which the
small signal model would apply.
B. The voltage gain would decrease dramatically as this capacitor would short
the signal to ground.
C. The voltage gain would be unaffected, but the Q point would shift towards
the triode region.
D. None of the other choices is correct.
Using the values from the previous question, assume that a 10000 µF capacitor is
placed in parallel with RS. Which of the following is true?
A. The voltage gain would increase to approximately 100, but the input signal
would have to be reduced to stay in the range of operation for which the
small signal model would apply.
B. The voltage gain would decrease dramatically as this capacitor would short
the signal to ground.
C. The voltage gain would be unaffected, but the Q point would shift towards
the triode region.
D. None of the other choices is correct.
Which of the following is true?
A. By displaying a large number of cycles, the FFT math function will give a good
approximation of the Fourier series for the displayed signal.
B. In order to get a good approximation of the Fourier series, it will be necessary to decrease
the horizontal scale until no more than 3 cycles of the signal are displayed.
C. In order to get a good approximation of the Fourier series for the displayed signal, it will
be necessary to decrease the vertical scale, i.e. fewer volts per division such that the
peaks of the signal extend beyond the screen limits in order to minimize the effects of
amplitude variations.
D. None of the other choices is correct.
Which of the following is true?
A. By displaying a large number of cycles, the FFT math function will give a good
approximation of the Fourier series for the displayed signal.
B. In order to get a good approximation of the Fourier series, it will be necessary to decrease
the horizontal scale until no more than 3 cycles of the signal are displayed.
C. In order to get a good approximation of the Fourier series for the displayed signal, it will
be necessary to decrease the vertical scale, i.e. fewer volts per division such that the
peaks of the signal extend beyond the screen limits in order to minimize the effects of
amplitude variations.
D. None of the other choices is correct.
For an n-channel MOSFET, if the gate voltage is above the threshold
voltage and is increased further:
A. The drain-source current will decrease and the saturation voltage will increase
B. Both the drain-source current and saturation voltage will increase
C. The drain-source current will increase and the saturation voltage will decrease
D. The drain-source current will decrease and the saturation voltage will decrease
For an n-channel MOSFET, if the gate voltage is above the threshold
voltage and is increased further:
A. The drain-source current will decrease and the saturation voltage will increase
B. Both the drain-source current and saturation voltage will increase
C. The drain-source current will increase and the saturation voltage will decrease
D. The drain-source current will decrease and the saturation voltage will decrease
The drain-source current is linearly proportional to the gate-source
voltage at a constant and small drain-source voltage.
True
False
The drain-source current is linearly proportional to the gate-source
voltage at a constant and small drain-source voltage.
True
False
In the circuit below containing an n-channel MOSFET, if Vgs is increased, Vds will:
A. Increase
B. Decrease
C. Stay the same
D. Not enough information
In the circuit below containing an n-channel MOSFET, if Vgs is increased, Vds will:
A. Increase
B. Decrease
C. Stay the same
D. Not enough information
In the circuit below containing an n-channel MOSFET, if the power supply
voltage is increased, the current through the drain resistor, R1, will:
A. Increase
B. Decrease
C. Stay the same
D. Not enough information
In the circuit below containing an n-channel MOSFET, if the power supply
voltage is increased, the current through the drain resistor, R1, will:
A. Increase
B. Decrease
C. Stay the same
D. Not enough information
The n-channel MOSFET in the circuit below has a 4-resistor DC bias
configuration. Assuming that Vin is a positive voltage and that Vgs>Vtn, Vgs
will be:
A.
B.
C.
D.
Less than Vin
Equal to Vin
Greater than Vin
Can’t tell
The n-channel MOSFET in the circuit below has a 4-resistor DC bias
configuration. Assuming that Vin is a positive voltage and that Vgs>Vtn, Vgs
will be:
A.
B.
C.
D.
Less than Vin
Equal to Vin
Greater than Vin
Can’t tell
The gain of the MOSFET amplifier below depends on the Q-point.
True
False
The gain of the MOSFET amplifier below depends on the source resistor.
True
False
The gain of the MOSFET amplifier below depends on the source resistor.
True
False
The gain of the MOSFET amplifier below depends on the power supply voltage.
True
False
The gain of the MOSFET amplifier below depends on the power supply voltage.
True
False