acdc10.adoc

1. Circuit Shepherd questions

1.1. pnp DC sweep ^[1]

Which DC sweep plot is correct? A or B?

1.2. Op amp circuit ^[2]

What’s Vx? 2V, 4V or 8V? Assume a very high current gain of the transistor by neglecting the base current.

1.3. Current sink ^[3]

Which switch would damage the circuit if opened? S1, S2 or S3?

1.4. pnp at DC ^[4]

What’s Vec? 6V, 8V or 10V? Assume a very high current gain of the transistor by neglecting the base current.

1.5. npn DC sweep ^[5]

Which DC-sweep plot corresponds to the given transistor circuit? A, B or C ?

1.6. npn group ^[6]

What’s Ix? 10mA, 12mA or 15mA? Assume a very high current gain of the transistors by neglecting the base currents.

1.7. CE pnp gain ^[7]

For slow changes of Vin, the small-signal gain is approximately -1. What’s the small-signal gain for fast changes? Is it approximately -1, -2, or -4? Assume the transistor to have infinite bandwidth.

1.8. push-pull ^[8]

What’s Vout? 4.9V, 5.9V or 6.9V? What’s Ix? 3mA, 4mA or 5mA? Assume a very high current gain of the transistors by neglecting the base currents.

1.9. Inverting opamp frequency response ^[9]

Which Bode plot is correct? A, B or C?

1.10. Non-inverting opamp frequency response ^[10]

Which Bode plot is correct? A, B, or C?

1.11. RC Bode plot ^[11]

Which circuit is correct? A, B, or C?

1.12. RC bode plot ^[12]

Which Bode plot is correct? A, B, or C?

1.13. Non-inverting opamp DC sum ^[13]

This is a non-inverting summing amplifier! What’s Vout? 3V, 4V or 8V? How can R4 be modified for a 6V Vout? 20k, 30k or 40k?

1.14. Comparator Schmitt trigger ^[14]

Which comparator based Schmitt Trigger circuit corresponds to the given hysteresis? A, B or C?

1.15. PMOS at DC ^[15]

What’s Vout? 4V, 5.3V or 6V?
What’s Vgs if Vin = -6V? -4V, -2V or 0V?

1.16. Op amp non-inverting frequency response ^[16]

Which circuit is correct? A, B or C? (Assume an ideal op-amp.)

1.17. CE pnp Bode plot ^[17]

Which Bode plot is correct? A or B? Assume the transistor to have infinite bandwidth.

1.18. Diode DC sweep ^[18]

Which circuit is correct? A, B or C?

1.19. Bode plot match ^[19]

Which passive filter circuit has a bode plot, most similar to that of the active filter circuit? A, B or C? Assume an ideal op-amp with infinite bandwidth.

1.20. Op amp inverting frequency response ^[20]

Which circuit is correct? A, B or C? (Assume an ideal op-amp.)

1.21. npn switches ^[21]

Which switch would NOT turn off the LED if closed? S1, S2 or S3?

1.22. Passive Bode plot ^[22]

Which circuit is correct? A, B or C?

1.23. npn switch LED ^[23]

Which switch would harm the LED if closed? S1, S2 or S3? Assume that the LED will be harmed at a current > 20mA.

1.24. Thevenin equivalent ^[24]

Which Thevenin equivalent circuit is correct? A, B or C?

1.25. S/H Req ^[25]

What’s the equivalent input resistance of an ADC with a Sample & Hold capacitance of 20 pF operating at a sample rate of 500 kHz? 1 kHz, 10 kHz or 100 kHz?

1.26. Op amp non-inverting ^[26]

What’s R1? 10k, 20k or 30k? What’s R2? 30k, 40k or 50k?

1.27. Resistor power ^[27]

Which resistor consumes the least power? R1, R2, R3 or R4? (Don’t calculate, just argue!)

1.28. Resistor current ^[28]

Estimate the current through R4! 1mA, 2mA or 4mA?

1.29. Op amp capacitor fix ^[29]

Which capacitor would you remove to fix this faulty opamp circuit? C1, C2, C3 or C4?

1.30. Current mirror ^[30]

Which circuit is not a current mirror? A, B or C? (For the current mirrors Iout = Iprog)

1.31. RLC Bode plot ^[31]

Which bode plot is correct? A, B or C? (Missing trace labels are part of the puzzle.)

1.32. npn at DC ^[32]

What’s Ix? 6mA, 10mA or 15mA? Assume a very high current gain of the transistors by neglecting the base currents.

1.33. Op amp Bode plot ^[33]

Which bode plot is correct? A, B or C?

1.34. pnp switches ^[34]

Which switch would double the LED current if closed? S1, S2 or S3?

1.35. Push-pull DC sweep ^[35]

Which DC sweep plot would be correct if S1 is closed? A or B?

1.36. Op amp DC sweep ^[36]

Estimate R1 of this non-inverting opamp circuit! 10k, 20k or 30k? (Hint: Substitute R2 and R3 with its Thévenin equivalent.)

1.37. Opamp DC sweep 2 ^[37]

What’s R2 of this non-inverting opamp circuit? 5k, 10k or 20k? (Hint: First find the Thévenin equivalent of R2 and R3.)

1.38. Current mirror power ^[38]

Which component consumes the most power? T1, T2, R1, R2 or R3?

1.39. Thevenin equivalent ^[39]

Which Thevenin equivalent circuit is correct? A, B or C?

1.40. Op amp summer ^[40]

Estimate R4 of this Summing Amplifier! 1k, 2k or 3k?

1.41. Norton equivalent ^[41]

Which Norton equivalent circuit is correct? A, B or C?

1.42. Thevenin equivalent match ^[42]

Which circuit has a unique Thèvenin equivalent? A, B, C or D?

1.43. pnp small-signal gain ^[43]

Which circuit does not have a small-signal gain of -10? A, B, C or D?

1.44. MCU load switch ^[44]

Which circuit won’t work? A, B, C or D?

1.45. Transformer Bode plot ^[45]

Which Bode plot is correct for ideal (k = 1) inductive coupling? A, B, or C? Which Bode plot is correct for non-ideal (k = 0.99) inductive coupling? A, B, or C?