# Linear Integrated Circuit Questions and Answers – Interpreting of Data Sheets – 2

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This set of Linear Integrated Circuit online test focuses on “Interpreting of Data Sheets – 2”.

1. How are input offset voltage of op-amp expressed
a) Microvolts per week
b) Nanovolts per week
c) Megavolts per week
d) Millivolts per week

Explanation: For long term stability the amount of change in input offset voltage with time is crucial and denoted as micro volts per week.

2. Find the expression for output offset voltage?
a) VooT = [RF/R1×Vio] + (RF×Io)
b) VooT = [1+(RF/R1)]×(Vio) + (RF×Io)
c) VooT = [1+(RF/R1)]/(Vio) + (RF×Io)
d) VooT = [RF/R1]×(Vio) + (RF/Io)

Explanation: Output offset voltage is expressed as a function of input offset current and input offset voltage, when is given as
VooT = [1+(RF/R1)]×(Vio) + (RF×Io).

3. Why it is necessary to calibrate all op-amp in the system periodically?
a) To maintain current drift of a system
b) To maintain output offset voltage in op-amp
c) To maintain accuracy and linearity of a system
d) None of the mentioned

Explanation: In practice, the output offset voltage in all op-amp circuit will change with time. Therefore, to maintain the desired accuracy and linearity of a system, it is necessary to calibrate all op-amps in that system periodically.
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4. Determine the maximum possible change in output offset voltage after 3 month if the LH0041C op-amp is initially nulled and room temperature, voltage across terminal, +Vcc & -Vee remain constant.
a) △VooT = 456.78mv
b) △VooT = 3.452mv
c) △VooT = 21.1mv
d) None of the mentioned

Explanation: For LH0041C,
△Vio/△t = 5µV/week and △Iio /△t = 2nA/week.
Due to the time drift △t=12 weeks (3months). The maximum possible change in output offset voltage,
△VooT = [[1+(RF/R1)]×(△Vio/△t)×△t]+[RF×(△Iio/△t) ×△t]= [(1+(250kΩ/1kΩ))×5µV×12] + [250kΩ×2µA×12] = 15.1mv+6mv
=> △VooT = 21.1mv.

5. How to minimize the drift in input signal amplifier without affecting the performance of the circuit?
a) All of the mentioned Choosing small value of external components
b) Enhancing the input signal amplifier
c) Reducing the gain of op-amp
d) All of the mentioned

Explanation: The amount of drift in input signal depends on the relative values of external components. So, if relatively small values are selected for external component then drift can be minimized.

6. An amplifier has a supply voltage ±15v. Compute its peak to peak output swing
a) 36v
b) 30v
c) 26v
d) 49v

Explanation: The peak to peak output swing depends on the value of the supply voltage ( which is +15v-(-15v) =30v ) and is always less than the value to maintain safe operation of op-amp.

7. Find out the incorrect statement.
a) Power consumption of op-amp decrease with increasing ambient temperature
b) Output short circuit current of op-amp decreases with increasing temperature.
c) Common mode voltage range of op-amp increases with increasing supply voltage value
d) Power consumption of op-amp decreases with increasing supply voltage

Explanation: If the power consumption as a function of supply voltage curve is drawn, it can be seen that the amount of dc power required to operate the op-amp under no-load condition increases with an increase in supply voltage.

8. Choose the temperature dependent parameter
a) Common mode rejection ratio
b) Voltage gain
c) Output voltage swing
d) Absolute maximum power dissipation

Explanation: Other than absolute maximum power dissipation the remaining are frequency dependent parameters.

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