Analog Circuits - Online Test

Q1. Group I gives two possible choices for the impedance Z in the diagram. The circuit elements in Z satisfy the conditions R2C2 > R1C1. The transfer functions V0/V1 represents a kind of controller.

Match the impedances in Group I with the type of controllers in Group II
 Group I                                                              Group II
                              
Answer : Option B
Explaination / Solution:



Q2. Consider the Schmidt trigger circuit shown below A triangular wave which goes from -12 to 12 V is applied to the inverting input of OPMAP. Assume that the output of the OPAMP swings from +15 V to -15 V. The voltage at the non-inverting input switches between

Answer : Option C
Explaination / Solution:

Let the voltage at non inverting terminal be V1, then after applying KCL at non inverting terminal side we have

If V0 swings from -15 to +15 V then V1 swings between -5 V to +5 V.

Q3.
The logic function implemented by the following circuit at the terminal OUT is

Answer : Option D
Explaination / Solution:

From the figure shown below it may be easily seen upper MOSFET are shorted and connected to Vdd thus OUT is 1 only when the node S is 0,

Since the lower MOSFETs are shorted to ground, node S is 0 only when input P and Q are 1. This is the function of AND gate.

Q4.
In the following transistor circuit,  , and 𝛽 and all the capacitances are very large

The mid-band voltage gain of the amplifier is approximately
Answer : Option D
Explaination / Solution:

The small signal model is shown in fig below


Q5.
Assuming the OP-AMP to be ideal, the voltage gain of the amplifier shown below is

Answer : Option A
Explaination / Solution:



Q6.
The transfer characteristic for the precision rectifier circuit shown below is (assume ideal OP-AMP and practical diodes)

Answer : Option B
Explaination / Solution:




Q7.
Consider the common emitter amplifier shown below with the following circuit parameters:


The resistance seen by the source vs is
Answer : Option B
Explaination / Solution:



Q8.
For the operational amplifier circuit shown, the output saturation voltages are ± 15V. The upper and lower threshold voltages for the circuit are, respectively.

Answer : Option B
Explaination / Solution:



Q9.
The circuit shown in the figure has an ideal opamp. The oscillation frequency and the condition to sustain the oscillations, respectively, are

Answer : Option D
Explaination / Solution:

By virtual ground property, we write


We equate imaginary part to zero, i.e.

The condition to sustain the oscillation is


Q10.
In the following a stable multivibrator circuit, which properties of  V0(t) depend on R2?

Answer : Option A
Explaination / Solution:

The R2  decide only the frequency.