MCQs on Logic Families

Digital Electronics MCQs

1. When an n-p-n transistor is used to make an inverter for positive logic, the transistor is forced into saturation when the input is high, because______.

a.  Saturated transistors have a high voltage gain

b. The high base current in saturation leads to a smaller turn off time

c. The output voltage(Vce) in saturation is very close to zero

d. The large stored charge in the base, in saturation, ensures a fast turn-off

2. Compared to a passive pull-up (resistor) output stage, the active pull-up (totem-pole) output stage has______.

a. Longer delays and higher power consumption

b. Shorter delays and higher power consumption

c. Shorter delays and lower power consumption

d. Longer delays and lower power consumption

3. In today's world, the almost exclusive logic family used for making digital circuits is______.

a. TTL

b. CMOS

c. RTL

d. NMOS

4. The logic family which belongs to non-saturated logic is_____.

a. ECL

b. CMOS

c. TTL

d. NMOS

5. Emitter-coupled logic (ECL) is the fastest bipolar transistor logic because______.

a. It uses differential inputs

b. It has no p-n-p transistors

c. It uses a circuit configuration that prevents the transistors from going into saturation

d. It uses current, rather than voltages, as the output variables

6. The digital logic family which has minimum power dissipation is_____.

a. CMOS

b. DTL

c. TTL

d. RTL

7. Which of the following is the fastest logic?

a. TTL

b. ECL

c. LSI

d. CMOS

8. The digital logic family which has the lowest propagation delay time among all the logic family members is____.

a. PMOS

b. TTL

c. CMOS

d. None of these

9. In digital ICs, Schottky transistors are preferred over normal transistors because of their______.

a. Higher propagation delay

b. Higher fan out

c. Lower propagation delay

d. Lower power dissipation

10. Which TTL logic gate is used for wired ANDing?

a. Totem pole

b. Tristate output

c. Open collector output

d. ECL gates

11. CMOS circuits are extensively used for ON-chip computers, mainly because of their extremely______.

a. Low power consumption

b. Large packing density

c. Low cost

d. High noise immunity

12. CMOS logic has the property of_____.

a. Increased capacitance and delay

b. Low static power dissipation

c. High noise margin

d. Decreased area

13. The problem of "current hogging" is associated with______.

a. CMOS gates

b. ECL gates

c. DCTL gates

d. DTL gates