Analog Circuits Practice Test 9

1. Given that the feedback factor of an astable multivibrator is 0.3, find the frequency of the output.

20Hz

22Hz

40Hz

20kHz

2. The output impedance of follower is less than that of a degenerated CS stage.

True

False

3. In an astable multivibrator using an op-amp, the feedback factor is 0.5 and the supply voltage is ±12V. What are the quasi-stable output state and the input to the non-inverting terminal?

Quasi-stable output = ±12V, Input to non inverting terminal = ±6V

Quasi-stable output = ±12V, Input to non inverting terminal = 0V

Quasi-stable output = ±12V, Input to non inverting terminal = ±12V

Quasi-stable output = ±6V, Input to non inverting terminal = ±12V

4. If g is the transconductance and r is the resistance due to channel length modulation - what is the total voltage gain if both M₂ and M₃ has channel length modulation?

R/ ((1/g + R) * g * (R || r) * R/ ((1/g || r) + R)

R/ ((1/g ) + R) * g *R * R *2g

R/ ((1/g || r)) * g *R * R/ ((1/g || r) + R)

R/ ((1/g || r) + R) * g * (R || r) * R * g

5. In the following C.S. stage, what is the gate voltage appearing across M₁?

V₁ * [(R₂ || R₃) / (R₁ || R₂ || R₃)]

V₁ * [(R₂ + R₃) / {R₁ + R₂) || R₃}]

V₁ * [(R₂ + R₃) / (R₁ + R₂ + R₃)]

V₁ * [(R₂ || R₃) / {R₁ + (R₂ ||R₃}]

6. Neglecting Channel Length Modulation, what is the output impedance of the following C.S. stage?

R₄ || [(R₂ + R₃) || R₁]

R₄ || (R₂ + R₃)

R₄

R₄ || R₂

7. If channel length modulation is neglected, what is the voltage gain for the following CG stage?

R_d/(1/g_m - R_s)

R_d/(3/g_m + R_s)

R_d/(1/g_m + R_s)

R_d/(2/g_m + R_s)

8. The current gain of a simple CG stage is approximate ____________

twice

unity

Infinity

9. If Channel Length Modulation is present and g_m is the transconductance of M₁, what happens to the output resistance of for a fixed V₂ in the following circuit?

(1 + (g_m * r_o)) * r_o + R_s

(1 + (g_m * r_o)) * R_s + r_o

(r_o + 2) * R_s

(1 + (g_m * r_o)) * R_s

10. Neglecting Channel Length Modulation, if the transconductance of the MOSFET increases, the gain of the follower stage will _________

doubles

decreases

doesn’t get affected

increases