operational amplifiers Flashcards
An ideal operational amplifier has
infinite output impedance
zero input impedance
infinite bandwidth
All of the above
infinite bandwidth
Another name for a unity gain amplifier is:
difference amplifier
comparator
single ended
voltage follower
voltage follower
The open-loop voltage gain (Aol) of an op-amp is the
external voltage gain the device is capable of
internal voltage gain the device is capable of
most controlled parameter
same as Acl
internal voltage gain the device is capable of
A series dissipative regulator is an example of a:
linear regulator
switching regulator
shunt regulator
dc-to-dc converter
linear regulator
A noninverting closed-loop op-amp circuit generally has a gain factor:
less than one
greater than one
of zero
equal to one
greater than one
In order for an output to swing above and below a zero reference, the op-amp circuit requires:
a resistive feedback network
zero offset
a wide bandwidth
a negative and positive supply
a negative and positive supply
Op-amps used as high- and low-pass filter circuits employ which configuration?
noninverting
comparator
open-loop
inverting
inverting
If ground is applied to the (+) terminal of an inverting op-amp, the (–) terminal will:
not need an input resistor
be virtual ground
have high reverse current
not invert the signal
be virtual groun
An astable multivibrator is also known as a:
one-shot multivibrator
free-running multivibrator
bistable multivibrator
monostable multivibrator
free-running multivibrator
With negative feedback, the returning signal:
aids the input signal
is proportional to output current
opposes the input signal
is proportional to differential voltage gain
opposes the input signal
What starts a free-running multivibrator?
a trigger
an input signal
an external circuit
nothing
nothing
A portion of the output that provides circuit stabilization is considered to be:
negative feedback
distortion
open-loop
positive feedback
negative feedback
How many leads does the TO-5 metal can package of an operational amplifier have?
8, 10, or 12
6, 8, or 10
8 or 14
8 or 16
8, 10, or 12
The closed-loop voltage gain of an inverting amplifier equals:
the ratio of the input resistance to the feedback resistance
the open-loop voltage gain
the feedback resistance divided by the input resistance
the input resistance
the feedback resistance divided by the input resistance
All of the following are basic op-amp input modes of operation EXCEPT
inverting mode
common-mode
double-ended
single-ended
inverting mode
A circuit whose output is proportional to the difference between the input signals is considered to be which type of amplifier?
common-mode
darlington
differential
operational
differential
With negative feedback, the returning signal
is proportional to the output current
is proportional to the differential voltage gain
opposes the input signal
aids the input signal
opposes the input signal
The voltage follower has a:
closed-loop voltage gain of unity
small open-loop voltage gain
closed-loop bandwidth of zero
large closed-loop output impedance
closed-loop voltage gain of unity
The ratio between differential gain and common-mode gain is called:
amplitude
differential-mode rejection
common-mode rejection
phase
common-mode rejection
In an open-loop op-amp circuit, whenever the inverting input (–) is negative relative to the noninverting input (+), the output will:
swing negative
close the loop
be balanced
swing positive
swing positive
If the input to a comparator is a sine wave, the output is a:
ramp voltage
sine wave
rectangular wave
sawtooth wave
rectangulae wave
What three subcircuits does a phase locked loop (PLL) consist of?
phase comparator, comparator, and VCO
phase comparator, bandpass filter, and VCO
phase comparator, bandpass filter, and demodulator
phase comparator, low-pass filter, and VCO
phase comparator, low-pass filter, and VCO
The major difference between ground and virtual ground is that virtual ground is only a:
voltage reference
current reference
power reference
difference reference
voltage reference
If an op-amp has one input grounded and the other input has a signal feed to it, then it is operating as what?
Common-mode
Single-ended
Double-ended
Noninverting mode
Single-ended
The Schmitt trigger is a two-state device that is used for:
pulse shaping
peak detection
input noise rejection
filtering
pulse shaping
The common-mode voltage gain is
smaller than differential voltage gain
equal to voltage gain
greater than differential voltage gain
None of the above
smaller than differential voltage gain
How many logic states does an S-R flip-flop have?
2
3
4
5
4
An output that is proportional to the addition of two or more inputs is from which type of amplifier?
differentiator
difference
summing
analog subtractor
summing
In a PLL, to obtain lock, the signal frequency must:
come within the lock range
be less than the capture frequency
come within the capture range
be greater than the capture frequency
come within the capture range
An ideal amplifier should have:
high input current
zero offset
high output impedance
moderate gain
zero offset
The magnitude of closed-loop voltage gain (Acl) of an inverting amplifier equals:
the ratio of the input resistance to the feedback resistance
the open-loop voltage gain Aol
the feedback resistance divided by the input resistance
the input resistance
the feedback resistance divided by the input resistance
What is the difference between common-mode and differential-mode input signals?
phase relationship
voltage
current
apparent power
phase relationship
A circuit that uses an amplifier with passive filter elements is called a(n):
relaxation oscillator
signal generator
differential amplifier
active filter
active filter
The input offset current equals the
average of two base currents
collector current divided by the current gain
difference between two base-emitter voltages
difference between two base currents
difference between two base currents
The center frequency of a band-pass filter is always equal to the
bandwidth
–3 dB frequency
bandwidth divided by Q
geometric average of the critical frequencies
geometric average of the critical frequencies
A zero-level detector is a
comparator with a sine-wave output
comparator with a trip point referenced to zero
peak detector
limiter
comparator with a trip point referenced to zero
A digital-to-analog converter is an application of the
scaling adder
voltage-to-current converter
noninverting amplifier
adjustable bandwidth circuit
scaling adder
If the value of resistor Rf in an averaging amplifier circuit is equal to the value of one input resistor divided by the number of inputs, the output will be equal to
the average of the individual inputs
the inverted sum of the individual inputs
the sum of the individual inputs
the inverted average of the individual inputs
the inverted average of the individual inputs
If the input to a comparator is a sine wave, the output is a
ramp voltage
sine wave
rectangular wave
sawtooth wave
rectangular wave
A basic series regulator has
an error detector
a load
a reference voltage
both an error detector and a reference voltage
both an error detector and a reference voltage
A comparator is an example of a(n)
active filter
current source
linear circuit
nonlinear circuit
nonlinear circuit
Initially, the closed-loop gain (Acl) of a Wien-bridge oscillator should be
Acl < 3
Acl > 3
0
Acl = 1
Acl > 3
In an averaging amplifier, the input resistances are
equal to the feedback resistance
less than the feedback resistance
greater than the feedback resistance
unequal
greater than the feedback resistance
A triangular-wave oscillator can consist of an op-amp comparator, followed by a(n)
differentiator
amplifier
integrator
multivibrator
integrator
The ramp voltage at the output of an op-amp integrator
increases or decreases at a linear rate
increases or decreases exponentially
is always increasing and never decreasing
is constant
increases or decreases at a linear rate
A two-pole high-pass active filter would have a roll-off rate of
40 dB/decade
–40 dB/decade
20 dB/decade
–20 dB/decade
–40 dB/decade
When using an OTA in a Schmitt-trigger configuration, the trigger points are controlled by
the Iout
the IBIAS
the Vout
both Iout and IBIAS
both Iout and IBIAS
The primary function of the oscillator in an isolation amplifier is to
convert dc to high-frequency ac
convert dc to low-frequency ac
rectify high-frequency ac to dc
produce dual-polarity dc voltages for the input to the demodulator
convert dc to high-frequency ac
An instrumentation amplifier has a high
output impedance
power gain
CMRR
supply voltage
CMRR
Circuits that shift the dc level of a signal are called
limiters
clampers
peak detectors
dc converters
clampers
In the classic three-op-amp instrumentation amplifier, the differential voltage gain is usually produced by the
first stage
second stage
mismatched resistors
output op-amp
first stage
