1. Variation in the operating frequency of op-amp causes
A. Variation in gain amplifier
B. Variation in gain phase angle
C. Variation in gain amplitude and its phase angle
D. None of the mentioned
Answer: C
The gain of the op-amp is a function of frequency. It will have a specific magnitude as well as a phase angle.
2. A graph of the magnitude of the gain versus frequency is called
A. Break frequency
B. Frequency response plot
C. Frequency stability plot
D. Transient response plot
Answer: B
A frequency response plot is obtained by plotting the gain of the op-amp responding to different frequencies.
3. In the frequency response plot, the frequency is expressed in
A. Anti-logarithmic scale
B. Logarithmic scale
C. Linear scale
D. Exponential scale
Answer: B
To accommodate large frequency ranges the frequency is assigned to a logarithmic scale.
4. Why the gain magnitude in the frequency response plot is expressed in decibels (dB.
A. To obtain gain > 105
B. To obtain gain < 105
C. To obtain gain = 0
D. To obtain gain = ∞
Answer: A
In the frequency response plot, gain magnitude is assigned a linear scale and is expressed in decibels to accommodate very high gain ( ≅ of the order 105 or higher).
5. Which technique is used to determine the stability of op-amp?
A. Frequency response plot
B. Transient response plot
C. Bode plot
D. All of the mentioned
Answer: C
Although frequency response and bode plots indicate the effect of frequency variation on gain, the Bode plot is generally used for stability determination and network design.
6. How many types of plots can be obtained in the AC analysis of the network using the Bode plot?
A. Five
B. Four
C. Three
Answer: D
Two types of plots can be obtained using the Bode plot. They are magnitude versus frequency and phase angle versus frequency plots.
7. What happens when the operating frequency of op-amp increases?
A. Gain of the amplifier decrease
B. Phase shift between output and input signal decrease
C. Gain and phase shift of amplifier decreases
D. None of the mentioned
Answer: A
When the operating frequency has increased the gain of the amplifier decrease. As it is linearly related to frequency, the phase shift is logarithmically related to frequency.
8. Which of the following causes change in gain and phase shift?
A. Internally integrated Resistor
B. Internally integrated inductors
C. Internally integrated Capacitor
D. All of the mentioned
Answer: C
The change in function of frequency is attributed to the internally integrated capacitor as well as a stray capacitor. These capacitors are due to the physical characteristic of the semiconductor device.
9. Which plot is not provided by the manufacturers?
A. Magnitude plot
B. Phase angle plot
C. Frequency response plot
D. None of the mentioned
Answer: B
Phase angle plots are not generally provided because phase shifts of later generation op-amp are less than 90o even at cross-over frequency.
10. Open-loop bandwidth of an op-amp extends its bandwidth from
A. 0 Hz to fo
B. 20dB to fo
C. 3dB to fo
D. 0.704dB to fo
Answer: A
The gain of the op-amp remains essentially constant from 0 to the break frequency fo and therefore rolls off at a constant rate of 20dB per decade. Thus, the open-loop bandwidth is the frequency band extending from 0Hz to fo.
