Analog circuits miscellaneous
- An amplifier has an open loop gain of 100, an input impedance of 1kΩ, and an out put impedance of 100 Ω. If a feedback network with a feedback factor of 0.99 is connected in a voltage series feedback mode then new input and output impedances are
(a)
(b)
(c)
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Zif = Zi (1 + βA) = 1 k (1 + 100 × 0.99) = 100 kΩ
Zof = Z0 = 100 = 1 Ω 1 + βA 100
Correct Option: C
Zif = Zi (1 + βA) = 1 k (1 + 100 × 0.99) = 100 kΩ
Zof = Z0 = 100 = 1 Ω 1 + βA 100
- In the circuit shown in the given figure, the type of feedback used is
-
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NA
Correct Option: B
NA
- In the single-stage transistor amplifier circuit shown in the given figure, if capacitor CE is removed, then, ac small-signal midband voltage gain of the amplifier
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With CE, voltage gainAυ = - -hfeRL hie + (1 + hfe)RE
If RE by passed with capacitor CE, AV will increase Hence, after removing CE mid band voltage gain decreases.Correct Option: B
With CE, voltage gainAυ = - -hfeRL hie + (1 + hfe)RE
If RE by passed with capacitor CE, AV will increase Hence, after removing CE mid band voltage gain decreases.
- If an input signal with non-zero dc component is applied to a low pass RC network, then dc component in the output will be
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NA
Correct Option: A
NA
- A junction transistor operating at room temperature with IC = 2 mA, where (kT / q) = 20 mV and β = 100. The values of parameter gm in mhos and rπ in ohm respectively are
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gm = IC = 2 = 0.08 VT 25 rm = β = 100 = 1250 gm 0.08 Correct Option: B
gm = IC = 2 = 0.08 VT 25 rm = β = 100 = 1250 gm 0.08