Deck 13: Basic Op-Amp Circuits

Question 1

Figure 6
Refer to Figure 6. You observe large decaying oscillations on the output. A likely cause is

A)Rf is open
B)C1 is wrong value
C)R_i is a wrong value
D)V_CC is open

Answer 1

C

Question 2

Figure 5 The input is a 500 Hz, 10 V_pp square wave centered about 0 V.
Refer to Figure 5. After steady- state conditions are reached, the output will be

A)1.0 Vpp
B)2.5 Vpp
C)10 Vpp
D)5 Vpp

Answer 2

D

Question 3

Figure 1 Assume that +V_out(max)= +13 V and -V_out(max)= -13 V
Refer to Figure 1. If the input is a 2 Vpp sine wave, the output will be

A)a ramp
B)a dc level
C)a square wave
D)an inverted sine wave

Answer 3

B

Question 4

Figure 4 The sine wave shown is the input signal.
Refer to Figure 4. The correct output waveform is represented by

A)(a)
B)(b)
C)(c)
D)(d)

Question 5

Figure 6
Refer to Figure 6. The output waveform is a

A)square wave
B)sine- wave
C)positive and negative triggers
D)none of the above

Question 6

The process of limiting the output of a comparator is called

A)bounding
B)clamping
C)hysteresis
D)none of the above

Question 7

Figure 2
Refer to Figure 2. Assume there is a fault and the output = -14 Vdc. A possible cause is

A)the feedback path is open
B)a power supply connection is open
C)A and B are both possible causes
D)none of the above

Question 8

Figure 1 Assume that +V_out(max)= +13 V and -V_out(max)= -13 V
Refer to Figure 1. If the input voltage is +11 V, the output will be

A)+11 V
B)+13 V
C)-13 V
D)-11 V

Question 9

Figure 1 Assume that +V_out(max)= +13 V and -V_out(max)= -13 V
Refer to Figure 1. The LTP is at

A)-3 V
B)-10 V
C)+10 V
D)+3 V

Question 10

Figure 3
Refer to Figure 3. Assume all inputs are +3.0 V. The output will be

A)-4.5 V
B)+1.5 V
C)-1.5 V
D)+4.5 V

Question 11

Hysteresis avoids noise by using

A)output limiting
B)positive feedback
C)very fast comparators
D)all of the above

Question 12

A simultaneous (flash)ADC is particularly useful when

A)high speed is required
B)noise rejection is required
C)there are many simultaneous input signals
D)the output must be a very large binary number

Question 13

Figure 6
Refer to Figure 6. The primary purpose of Ri is to

A)attenuate the output
B)provide a path for bias current
C)avoid output drift
D)avoid noise on the output

Question 14

Figure 5 The input is a 500 Hz, 10 V_pp square wave centered about 0 V.
Refer to Figure 5. The primary purpose of Rf is to

A)provide a path for bias current
B)prevent noise from affecting the output
C)attenuate the signal
D)avoid drift

Question 15

Figure 5 The input is a 500 Hz, 10 V_pp square wave centered about 0 V.
Refer to Figure 5. Rc is in the circuit to balance the bias currents. A good value for Rc is

A)100 k▲
B)51 k▲
C)1.0 k▲
D)9.1 k▲

Question 16

If a capacitor is charged with a constant current, the voltage across the capacitor is

A)constant
B)decreases
C)increases in a linear manner
D)increases in a non- linear manner

Question 17

Figure 4 The sine wave shown is the input signal.
Refer to Figure 4. If the zener were reversed, the output would

A)have a longer positive output
B)be the inverse
C)have a shorter positive output
D)not change

Question 18

Figure 1 Assume that +V_out(max)= +13 V and -V_out(max)= -13 V
Refer to Figure 1. The UTP is at

A)+10 V
B)-3 V
C)-10 V
D)+3 V

Question 19

Figure 2
Refer to Figure 2. The current in Rf is

A)200 µA
B)100 µA
C)500 µA
D)1.0 mA

Question 20

The purpose of a zener diode between the output and inverting input of a comparator is to

A)limit the output voltage
B)set the upper and lower trip points
C)limit the input voltage
D)provide a stable comparison level for the input

Question 21

A practical integrator circuit often uses an inductor in the feedback path.

Question 22

Figure 3
Refer to Figure 3. An open input resistor will

A)cause the output to be zero
B)appear as a 3 V input
C)cause the output to saturate
D)none of the above

Question 23

The purpose of a priority encoder in a flash ADC is to determine

A)the sequence of binary numbers to send to the output
B)which input to encode first
C)which input has the highest value
D)the number of output bits required

Question 24

An integrator circuit is useful in wave shaping applications.

Question 25

A scaling amplifier is a summing amplifier with weighted inputs.

Question 26

The output of a differentiator represents the rate of change of the input.

Question 27

The output of a comparator is normally in one of two states.

Question 28

Figure 6
Refer to Figure 6. After steady- state conditions are reached, the output will be

A)2.5 Vpp
B)5 Vpp
C)10 Vpp
D)1.0 Vpp

Question 29

An R/2R ladder is generally used as an ADC.

Question 30

Figure 2
Refer to Figure 2. VOUT is

A)-2.0 V
B)+1.0 V
C)+2.0 V
D)-5.0 V

Question 31

A flash ADC with a four- digit binary output requires 8 comparators.

Question 32

Figure 5 The input is a 500 Hz, 10 V_pp square wave centered about 0 V.
Refer to Figure 5. If C1 should open, the output will be

A)a 500 Hz triangle
B)an inverted 500 Hz square wave
C)a non- inverted 500 Hz square wave
D)a dc level

Question 33

Figure 2
Refer to Figure 2. The circuit is a

A)averaging amplifier
B)A/D converter
C)summing amplifier
D)scaling amplifier

Question 34

A differentiator circuit can output a square wave from a sine wave input.

Question 35

Figure 5 The input is a 500 Hz, 10 V_pp square wave centered about 0 V.
Refer to Figure 5. The output waveform is a

A)sine- wave
B)square wave with the opposite phase
C)positive and negative triggers
D)none of the above