CHAPTER 12 FLOYD

very low

Common-mode gain is A. very high B. very low C. always unity D. unpredictable

an identical signal appears on both inputs

In the common mode, A. both inputs are grounded B. the output are connected together C. an identical signal appears on both inputs D. the output signals are in-phase

opposite polarity signals are applied to the inputs

In the differential mode, A. opposite polarity signals are applied to the inputs B. the gain is 1 C. the output are different amplitudes D. only one supply voltage us used

one input is grounded and a signal is applied to the other

When an op-amp is operated in the single-ended mode, the output is grounded A. one input is grounded and a signal is applied to the other B. both inputs are connected together C. the output is not inverted

zero the output error voltage

The purpose of offset nulling is to A. reduce gain B. equalize the input signals C. zero the output error voltage

answer a and c

The use of negative feedback A. reduces the voltage gain of an op-amp B. makes the op-amp oscillate C. makes linear operation possible D. answer a and c

stays the same

When negative feedback is used, the gain-bandwidth product of an op-amp A. increases B. decreases C. stays the same D. fluctuates

low power

Which of the following characteristics does not necessarily apply to an op-amp? A. high gain B. low power C. high input impedance D. low output impedance

zero

With zero volts on both inputs, an op-amp ideally should have an output equal to A. the positive supply voltage B. the negative supply voltage C. zero D. the CMRR

remains at 25

A certain inverting amplifier has a closed-loop gain of 25. The op-amp has an open-loop gain of 100,000. if another op-amp with an open loop gain of 200,000 is substituted in the configuration, the closed-loop gain A. doubles B. drops to 12.5 C. remains at 25 D. increases slightly

101

A certain inverting amplifier has an Ri of 0.1 kΩ and an Rf of 100 kΩ. The closed loop gain is A. 100,000 B. 1000 C. 101 D. 100

99.3μA

A certain op-amp has a bias current of 50μA and 49.3μA. The input offset current is A. 700 nA B. 99.3μA C. 49.7μA D. none of these

answer a and c

A differential amplifier A. is part of an op-amp B. has one input and one output C. has two outputs D. answer a and c

has all of these

A voltage follower A. has a gain of 1 B. is noninverting C. has no feedback resistor D. has all of these

two inputs and one output

An integrated circuit (IC) op-amp has A. two inputs and two outputs B. one input and one-output C. two inputs and one output

answer a and b

Each RC circuit in an op-amp A. causes the gain to roll off at - 6 dB/octave B. causes the gain to roll off at - 20 db/octave C. reduces the midrange gain by 3 dB D. answer a and b

fed back to the inverting input

For an op-amp with negative feedback, the output is A. equal to the input B. increased C. fed back to the inverting input D. fed back to the noninverting input

answers b and c

If Av(d) = 3500 and Acm = 0.35, the CMRR is A. 1225 B. 10,000 C. 80 dB D. answers b and c

answer a and c

If a certain op-amp has a closed-loop gain of 20 and an upper critical frequency of 10 MHz, the gain-bandwidth product is A. 200 MHz B. 10 MHz C. the unity-gain frequency D. answer a and c

5,000,000 Hz

If a certain op-amp has a midrange open-loop gain of 200,000 and a unity gain frequency of 5 MHz, the gain-bandwidth product is A. 200,000 Hz B. 1 x 1012 Hz C. 5,000,000 Hz D. not determinable from the information

increases

If the feedback resistor in Question 17 is open, the voltage gain is A. increases B. decreases C. is not affected D. depends on Ri

increases the input impedance and the bandwidth

Negative feedback A. increases the input and output impedances B. increases the input impedance and the bandwidth C. decreases the output impedance and the bandwidth D. does not affect impedances of bandwidth

1

Of the valued listed, the most realistic value for open-loop gain of an op-amp is A. 1 B. 2000 C. 80 db D. 100,000

the internal RC circuits

Phase shift through an op-amp is caused by A. the internal RC circuits B. the external RC circuits C. the gain roll-off D. negative feedback

100 kHz

The bandwidth of a dc amplifier having an upper critical frequency of 100 kHz is A. 100 kHz B. unknown C. infinity D. 0 kHz

9 kHz

The bandwidth of an ac amplifier having a lower critical frequency of 1 kHz and an upper critical frequency of 10 kHz is A. 1 kHz B. 9 kHz C. 10 kHz D. 11 kHz

the unity-gain frequency

The frequency at which the open-loop gain is equal to 1 is called A. the upper critical frequency B. the cutoff frequency C. the notch frequency D. the unity-gain frequency

extends from 0 Hz to the upper critical frequency

The midrange open-loop of an op amp A. extends from lower critical frequency to the upper critical frequency B. extends from 0 Hz to the upper critical frequency C. rolls off at 20 db/decade beginning at 0 Hz D. answers a and c

1.5 V/μs

The output of a particular op-amp increases 8 V in 12 μs. The slew rate is A. 96 V/μs B. 0.67 V/ μs C. 1.5 V/μs D. none of the above