VLSI Design Multiple Choice Questions and Answers

61. Which alteration is made in the manufacture of a TTL gate to create an open-collector output?

1. The output transistors are replaced by diodes.
2. The input transistor is replaced by a diode.
3. The output transistors are missing.
4. The top output transistor is missing.

62. Which of the following are not characteristics of TTL logic gates?

1. Totem-pole output
2. Bipolar transistors
3. CMOS transistors
4. Multiemitter transistors

63. Which of the following input levels would not be a valid HIGH for a TTL gate?

1. 2.4 V
2. 2.1 V
3. 1.8 V
4. All are valid.

64. Which of the following is a concern when using CMOS type devices?

1. mechanical shock
2. electrostatic discharge
3. fan out
4. under voltage

65. Which of the following is a special type of transistor used in the TTL series to improve speed characteristics?

1. Belrus
2. Shockley
3. Brattain
4. Schottky

66. When setting the voltage for an external device that must interface with an FPGA, you must change the value of

1. VCCIO
2. VDDIN
3. VDDiO
4. VCCIN

67. Which of the following digital IC logic families is most susceptible to static discharge?

1. RTL
2. ECL
3. MOS
4. TTL

68. Which of the following is not a common logic family used today?

1. RTL
2. ECL
3. TTL
4. CMOS

69. Which of the following is not a solution to interface problems between CMOS and TTL?

1. pull-up resistor
2. pull-down resistor
3. level-shifter
4. buffer

70. Which of the following levels would not be a valid LOW for a TTL gate?

1. 0.1 V
2. 0.7 V
3. 1.0 V
4. All are valid.