ET1310 Solid State Devices Chapter 6

In the common mode, (a) both inputs are grounded (b) the outputs are connected together (c) an identical signal appears on both inputs (d) the output signals are in phase

(c) an identical signal appears on both inputs

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

(c) fed back to the inverting input

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

(c) remains at 25

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

(c) two inputs and one output

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

(c) zero

A differential amplifier (a) is part of an op-amp (b) has one input and one output (c) has two outputs (d) answers (a) and (c)

(d) answers (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) answers (a) and (c)

(d) answers (a) and (c)

A voltage-follower (a) has a gain of one (b) is noninverting (c) has no feedback resistor (d) answers (a), (b), and (c)

(d) answers (a), (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)

(d) answers (b) and (c)

Of the values listed, the most realistic value for open-loop gain of an op-amp is (a) 1 (b) 2000 (c) 80dB (d)100,000

(d)100,000

16. 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 or bandwidth

(b) increases the input impedance and the bandwidth

When a differential amplifier is operated single-ended, (a) the output is grounded (b) one input is grounded and a signal is applied to the other (c) both inputs are connected together (d) the output is not inverted

(b) one input is grounded and a signal is applied to the other

Common-mode gain is (a) very high (b) very low (c) always unity (d) unpredictable

(b) very low

If the feedback resistor in Question 17 is open, the voltage gain (a) increases (b) decreases (c) is not affected (d) depends on Ri

(a) increases

In the differential mode, (a) opposite polarity signals are applied to the inputs (b) the gain is 1 (c) the outputs are different amplitudes (d) only one supply voltage is used

(a) opposite polarity signals are applied to the inputs

The output of a particular op-amp increases 8 V in 12 ms. The slew rate is (a) 96 V/ms (b) 0.67 V/ms (c) 1.5 V/ms (d) none of these

(b) 0.67 V/ms

Which of the following characteristics does not necessarily apply to an op-amp? (a) is part of an op-amp (b) has one input and one output (c) has two outputs (d) answers (a) and (c)

(b) has one input and one output

A certain noninverting amplifier has an Ri of 1.0 k and an Rf of 100 k. The closed-loop gain is (a) 100,000 (b) 1000 (c) 101 (d) 100

(c) 101

Differential gain is (a) very high (b) very low (c) dependent on the input voltage (d) about 100

a) very high

A certain op-amp has bias currents of 50 mA and 49.3 mA. The input offset current is (a) 700 nA (b) 99.3 mA (c) 49.65 mA (d) none of these

(a) 700 nA