Integrated Circuit Logic Families MCQs

Question 1

What does ECL stand for?

Accepted Answer

It stands for emitter-coupled logic; all of the emitters of the input transistors are connected together and each transistor functions as an emitter follower.

Answer

It stands for electron-coupled logic; all of the devices used within the gates are N-type transistors.

Answer

It stands for emitter-coupled logic; all of the inputs are coupled into the device through the emitters of the input transistors.

Answer

It stands for energy-coupled logic; the input energy is amplified by the input transistors and allows the device to deliver higher output currents.

Question 2

What is unique about TTL devices such as the 74S00?

Accepted Answer

The devices use Schottky transistors and diodes to prevent them from going into saturation; this results in faster turn on and turn off times, which translates into higher frequency operation.

Answer

The gate transistors are silicon (S), and the gates therefore have lower values of leakage current.

Answer

The S denotes the fact that a single gate is present in the IC rather than the usual package of 2–6 gates.

Answer

The S denotes a slow version of the device, which is a consequence of its higher power rating.

Question 3

Generally, the voltage measured at an unused TTL input would typically be measured between:

Accepted Answer

1.4 to 1.8 V.

Answer

0 to 5 V.

Answer

0 to 1.8 V.

Answer

0.8 to 5 V.

Question 4

The IEEE/ANSI notation of an internal underlined diamond denotes:

Accepted Answer

open-collector outputs.

Answer

totem-pole outputs.

Answer

quadrature amplifiers.

Answer

tristate buffers.

Question 5

The bipolar TTL logic family that was developed to increase switching speed by preventing transistor saturation is:

Accepted Answer

emitter-coupled logic (ECL) and transistor-transistor logic (TTL).

Answer

emitter-coupled logic (ECL).

Answer

current-mode logic (CML).

Answer

transistor-transistor logic (TTL).

Question 6

________ output levels would not be a valid LOW for a TTL

Accepted Answer

All of the above.

Answer

0.2 V

Answer

0.3 V

Answer

0.5 V

Question 7

The number of gates that can be connected to a single output without exceeding the current ratings of the gate is called ________.

Accepted Answer

fan-out

Answer

propagation

Answer

dissipation

Answer

SSI

Question 8

An open-collector TTL gate ________.

Accepted Answer

can sink current but cannot source current

Answer

can source current but cannot sink current

Answer

cannot source or sink current

Answer

can sink more current than a standard TTL gate

Question 9

In a DIP the spacing between pins is typically ________.

Accepted Answer

100 mils

Answer

5 mils

Answer

10 mils

Answer

50 mils