EEE 334 Exam Questions with Correct Answers Latest Update 2025-2026
What does an offset nulling terminal do? - Answers It allows for the application of a
potentiometer to an opamp. The pot's resistance value can be adjusted with a knob, allowing it
to dull the V0s (offset voltage supplied by a cheap opamp) so that the opamps output voltage
across the "short" is 0.
How can you block offset voltage from an opamp without using an offset nulling terminal? -
Answers Use a capacitively coupled inverting amp - A capacitor is placed in series with the input
signal, effectively acting as a high-pass filter. It blocks the DC portion of the input signal from
reaching the amplifier's inverting terminal, preserving the amplifier's DC biasing conditions.
What is the input bias current of opamps? - Answers the DC current which must be supplied to
the op-amp inputs for proper operation. So when we say opamps have zero current flowing
inward that is not necessarily true although ideally this current is zero
What is input offset current of opamps? - Answers the difference between bias current at both
terminals
How do you reduce input bias current of opamps? - Answers Add a resistor between the non-
inverting input and ground (at point 2 you add R3)
What is offset voltage of an opamp? - Answers the small, unwanted DC input voltage that must
be applied across its input terminals to force the output to zero volts. With offset voltage, the
output of the op amp (difference between Vn and Vp) will not be 0V.
What is impedance? - Answers Impedance is the combined effect of resistance (from resistors)
and reactance (from inductors and capacitors) that impedes the flow of electrical current.
What is op amp input impedance ideally? - Answers Input impedance is the opposition to
current entering the input terminals, ideally infinite to prevent loading (or stealing energy /
current from) the signal source. The input impedance is what the signal source (e.g., a sensor or
another amplifier) "sees" when it connects to the op amp's input.
What is op amp output impedance ideally? - Answers Output impedance is the opposition to
current leaving the output terminals, ideally zero so the op amp can drive any load without
voltage drop. The output impedance is what the load (e.g., a speaker or another circuit) "sees"
when it is connected to the op amp's output.
If there is infinite input impedance in an op amp, what does that mean? - Answers There is no
current flowing into the op amp
What is the differential input of an amp? - Answers the differential input is the voltage difference
between the two inputs (V+ and V-), which is the desired signal to be amplified
What is common-mode input? - Answers The common-mode input is the average voltage
, present on both inputs, effectively the voltage shared by both inputs and often a source of
unwanted noise or interference
What is differential gain? - Answers Differential gain (Ad) is the ratio of the amplifier's output to
the difference between its two input signals. A well-designed differential amplifier has a high
differential gain (infinite)
What is common mode gain? - Answers while common-mode gain (Acm) is the ratio of the
output to the average (or common) voltage applied to both inputs. Ideally want a low common-
mode gain (0) to effectively reject unwanted common-mode noise.
Purpose of inverting closed loop configuration of an op amp - Answers An inverting op-amp
configuration provides negative voltage gain, meaning the output signal is 180 degrees out of
phase with the input signal.
What is the weighted summer closed loop amp configuration? - Answers an inverting
operational amplifier configuration that sums input voltages, each scaled by a different weight
determined by the ratio of the feedback resistor to the respective input resistor
What is the non-inverting op-amp configuration? - Answers uses an operational amplifier with
negative feedback and has the input signal applied to the non-inverting (+) terminal, resulting in
an output signal that is in phase with the input, meaning it amplifies the signal without inverting
its polarity
What is the inverting integrator op amp circuit? - Answers produces an output voltage
proportional to the negative time-integral of its input voltage, achieved by replacing the
feedback resistor of a standard inverting amplifier with a capacitor.
What is the op-amp differentiator circuit? - Answers produces an output voltage proportional to
the time-derivative of its input voltage, meaning it measures the rate of change of the input
signal. It is essentially an inverting amplifier with the capacitor placed at the input and a resistor
in the feedback path.
What is the function of a difference amp? - Answers to measure the difference between two
input signals while rejecting common-mode noise. It achieves this by providing an output
voltage proportional to the difference between its two inputs and effectively amplifying the
wanted signal and attenuating or canceling unwanted signals that are present on both input
lines (common-mode signals).
What is the common mode rejection ratio? - Answers the degree to which a differential amp
rejects the common-mode inputs
What is wrong with difference amps having low input impedance? - Answers The source
impedance will have an effect on gain
What does an offset nulling terminal do? - Answers It allows for the application of a
potentiometer to an opamp. The pot's resistance value can be adjusted with a knob, allowing it
to dull the V0s (offset voltage supplied by a cheap opamp) so that the opamps output voltage
across the "short" is 0.
How can you block offset voltage from an opamp without using an offset nulling terminal? -
Answers Use a capacitively coupled inverting amp - A capacitor is placed in series with the input
signal, effectively acting as a high-pass filter. It blocks the DC portion of the input signal from
reaching the amplifier's inverting terminal, preserving the amplifier's DC biasing conditions.
What is the input bias current of opamps? - Answers the DC current which must be supplied to
the op-amp inputs for proper operation. So when we say opamps have zero current flowing
inward that is not necessarily true although ideally this current is zero
What is input offset current of opamps? - Answers the difference between bias current at both
terminals
How do you reduce input bias current of opamps? - Answers Add a resistor between the non-
inverting input and ground (at point 2 you add R3)
What is offset voltage of an opamp? - Answers the small, unwanted DC input voltage that must
be applied across its input terminals to force the output to zero volts. With offset voltage, the
output of the op amp (difference between Vn and Vp) will not be 0V.
What is impedance? - Answers Impedance is the combined effect of resistance (from resistors)
and reactance (from inductors and capacitors) that impedes the flow of electrical current.
What is op amp input impedance ideally? - Answers Input impedance is the opposition to
current entering the input terminals, ideally infinite to prevent loading (or stealing energy /
current from) the signal source. The input impedance is what the signal source (e.g., a sensor or
another amplifier) "sees" when it connects to the op amp's input.
What is op amp output impedance ideally? - Answers Output impedance is the opposition to
current leaving the output terminals, ideally zero so the op amp can drive any load without
voltage drop. The output impedance is what the load (e.g., a speaker or another circuit) "sees"
when it is connected to the op amp's output.
If there is infinite input impedance in an op amp, what does that mean? - Answers There is no
current flowing into the op amp
What is the differential input of an amp? - Answers the differential input is the voltage difference
between the two inputs (V+ and V-), which is the desired signal to be amplified
What is common-mode input? - Answers The common-mode input is the average voltage
, present on both inputs, effectively the voltage shared by both inputs and often a source of
unwanted noise or interference
What is differential gain? - Answers Differential gain (Ad) is the ratio of the amplifier's output to
the difference between its two input signals. A well-designed differential amplifier has a high
differential gain (infinite)
What is common mode gain? - Answers while common-mode gain (Acm) is the ratio of the
output to the average (or common) voltage applied to both inputs. Ideally want a low common-
mode gain (0) to effectively reject unwanted common-mode noise.
Purpose of inverting closed loop configuration of an op amp - Answers An inverting op-amp
configuration provides negative voltage gain, meaning the output signal is 180 degrees out of
phase with the input signal.
What is the weighted summer closed loop amp configuration? - Answers an inverting
operational amplifier configuration that sums input voltages, each scaled by a different weight
determined by the ratio of the feedback resistor to the respective input resistor
What is the non-inverting op-amp configuration? - Answers uses an operational amplifier with
negative feedback and has the input signal applied to the non-inverting (+) terminal, resulting in
an output signal that is in phase with the input, meaning it amplifies the signal without inverting
its polarity
What is the inverting integrator op amp circuit? - Answers produces an output voltage
proportional to the negative time-integral of its input voltage, achieved by replacing the
feedback resistor of a standard inverting amplifier with a capacitor.
What is the op-amp differentiator circuit? - Answers produces an output voltage proportional to
the time-derivative of its input voltage, meaning it measures the rate of change of the input
signal. It is essentially an inverting amplifier with the capacitor placed at the input and a resistor
in the feedback path.
What is the function of a difference amp? - Answers to measure the difference between two
input signals while rejecting common-mode noise. It achieves this by providing an output
voltage proportional to the difference between its two inputs and effectively amplifying the
wanted signal and attenuating or canceling unwanted signals that are present on both input
lines (common-mode signals).
What is the common mode rejection ratio? - Answers the degree to which a differential amp
rejects the common-mode inputs
What is wrong with difference amps having low input impedance? - Answers The source
impedance will have an effect on gain
