Integrated Circuit Logic Families MCQs

Question 1

Which of the following statements apply to CMOS devices?

Accepted Answer

All of the above.

Answer

The devices should not be inserted into circuits with the power on.

Answer

All tools, test equipment, and metal workbenches should be tied to earth ground.

Answer

The devices should be stored and shipped in antistatic tubes or conductive foam.

Question 2

What must be done to interface CMOS to TTL?

Accepted Answer

As long as the CMOS supply voltage is 5 V, they can be interfaced; however, the fan-out of the CMOS is limited to two TTL gates.

Answer

A dropping resistor must be used on the CMOS 12 V supply to reduce it to 5 V for the TTL.

Answer

A 5 V Zener diode must be placed across the inputs of the TTL gates in order to protect them from the higher output voltages of the CMOS gates.

Answer

The two series cannot be interfaced without the use of special interface buffers designed for that purpose, such as the open-collector buffers.

Question 3

What is the static charge that can be stored by your body as you walk across a carpet?

Accepted Answer

Over 30,000 volts

Answer

300 volts

Answer

3,000 volts

Answer

30,000 volts

Question 4

Which of the following logic families has the highest noise margin?

Accepted Answer

HCMOS

Answer

TTL

Answer

LS TTL

Answer

CMOS

Question 5

A "floating" TTL input may be defined as:

Accepted Answer

unused input that is not connected.

Answer

unused input that is tied to Vcc through a 1 k resistor.

Answer

unused input that is tied to used inputs.

Answer

unused input that is tied to the ground.

Question 6

Which of the logic families listed below allows the highest operating frequency?

Accepted Answer

ECL

Answer

74AS

Answer

HCMOS

Answer

54S

Question 7

Whenever a totem-pole TTL output goes from LOW to HIGH, a high-amplitude current spike is drawn from the Vcc supply. How is this effect corrected to a digital circuit?

Accepted Answer

By connecting a radio-frequency capacitor from Vcc to ground.

Answer

By using a switching power supply

Answer

By connecting a capacitor from Vout to ground

Answer

By connecting a large resistor from Vcc to Vout

Question 8

What is the increase in switching speed between 74LS series TTL and 74HC/HCT (High-Speed CMOS)?

Accepted Answer

10

Answer

5

Answer

50

Answer

100

Question 9

A logic signal experiences a delay in going through a circuit. The two propagation delay times are defined as:

Accepted Answer

tPLH and tPHL.

Answer

tDLH and tDHL.

Answer

tHPL and tlph.

Answer

tLDH and tHDL.