21. During the relaxation effect, electron flow occurs in
A. short pulses
B. at a steady-state level
C. large pulses
D. very large pulses
Answer: A
During the relaxation effect, electron flow occurs in short pulses rather than at a steady-state level.
22. Line impedance is given by
A. (L/C)2
B. (C/L)2
C. (L/C)1/2
D. (C/L)1/2
Answer: C
The line impedance Zo is given by (L/C.1/2 where L and C are values per unit length of the bus.
23. IR drops brings ______ in noise margin.
A. increase
B. decrease
C. does not affect
D. stabilization
Answer: B
IR drops bring about deterioration in noise margins. Transient voltages induced in either Vdd or Vss rail may lead to noise margin problems.
24. In negative logic convention, the Boolean Logic [1] is equivalent to:
A. +VDD
B. 0 V
C. -VDD
D. None of the mentioned
Answer: B
In negative logic convention, the Boolean Logic [1] is equivalent to 0 V and Logic ‘0’ is equivalent to +VDD.
25. In positive logic convention, the true state is represented as:
A. 1
B. 0
C. -1
D. -0
Answer: A
In positive logic convention, the Boolean logic ‘1’ is known to be representing the true state.
26. In a CMOS logic circuit the n-MOS transistor acts as:
A. Load
B. Pull up network
C. Pull down the network
D. Not used in CMOS circuits
Answer: C
A static CMOS gate has an nMOS pull-down network to connect the output to 0 (GND.
27. In a CMOS logic circuit the p-MOS transistor acts as:
A. Pull down network
B. Pull up network
C. Load
D. Short to ground
Answer: B
A static CMOS gate has a pMOS pull-up network to connect the output to VDD (1).
28. When both nMOS and pMOS transistors of CMOS logic gates are ON, the output is:
A. 1 or Vdd or HIGH state
B. 0 or ground or LOW state
C. Crowbarred or Contention(X)
D. None of the mentioned
Answer: C
The crowbarred (or contention) X level exists when both pull-up and pull-down transistors are simultaneously turned ON. Contention between the two networks results in an indeterminate output level and dissipates static power.
29. Free running multivibrator is also called as
A. Stable multivibrator
B. Voltage control oscillator
C. Square wave oscillator
D. Pulse stretcher
Answer: B
Free-running multivibrator operates at a frequency that is determined by an external tuning capacitor and a resistor. On applying a dc control voltage the frequency can be shifted on either side. This frequency deviation is directly proportional to the dc control voltage and hence it is called as ‘voltage controlled oscillator’.
30. The output voltage of the phase detector is
A. Phase voltage
B. Free running voltage
C. Error voltage
D. None of the mentioned
Answer: c
The phase detector compares the input frequency with the feedback frequency and produces an output dc voltage called an error voltage.
