# Digital Circuits Questions and Answers – Register-Transistor Logic(RTL)

This set of Digital Electronics/Circuits Multiple Choice Questions & Answers (MCQs) focuses on “Register-Transistor Logic(RTL)”.

1. All input of NOR as low produces result as __________
a) Low
b) Mid
c) High
d) Floating

Explanation: All input of NOR as low produces the result as high, whereas, rest all conditions produce output as low.

2. In RTL NOR gate, the output is at logic 1 only when all the inputs are at __________
a) logic 0
b) logic 1
c) +10V
d) Floating

Explanation: RTL NOR gate behaves as NOR gate and the output of NOR gate will be 1 only when all the inputs are at logic 0 and in rest conditions of the input, the output is 0.

3. Resistor–transistor logic (RTL) is a class of digital circuits built using _______ as the input network and _______ as switching devices.
a) Resistors, bipolar junction transistors (BJTs)
b) Bipolar junction transistors (BJTs), Resistors
c) Capacitors, resistors
d) Resistors, capacitors

Explanation: Resistor–transistor logic (RTL) is a class of digital circuits built using resistors as the input network and bipolar junction transistors (BJTs) as switching devices.

4. RTL consists of a common emitter stage with a _______ connected between the base and the input voltage source.
a) collector
b) base resistor
c) capacitor
d) inductor

Explanation: RTL consist of a common emitter stage with a base resistor connected between the base and the input voltage source. The role of base resistor is to expand the negligible transistor input voltage range (about 0.7 V) to the logical “1” level (about 3.5 V) by converting the input voltage into a current. Thus, base resistor plays a major role in biasing of the transistor.

5. The role of the _______ is to convert the collector current into a voltage in RTL.
a) Collector resistor
b) Base resistor
c) Capacitor
d) Inductor

Explanation: The role of the collector resistor is to convert the collector current into a voltage; its resistance is chosen high enough to saturate the transistor and low enough to obtain low output resistance. Base Resistor is to provide the necessary biasing to the base of the transistor in order to activate it.

6. The limitations of the one transistor RTL NOR gate are overcome by __________
a) Two-transistor RTL implementation
b) Three-transistor RTL implementation
c) Multi-transistor RTL implementation
d) Four-transistor RTL implementation

Explanation: The limitations of the one transistor RTL NOR gate are overcome by the use of multi transistor RTL. It consists of a set of parallel connected transistor switches driven by the logic inputs.

7. The primary advantage of RTL technology was that __________
a) It results as low power dissipation
b) It uses a minimum number of resistors
c) It uses a minimum number of transistors
d) It operates swiftly

Explanation: The primary advantage of RTL technology was that it uses a minimum number of transistors. It consists of registers in large amount and it results in as high power dissipation. The resistors act as the input network and the transistors performs the switching operation.

8. The disadvantage of RTL is that __________
a) It uses a maximum number of resistors
b) It results in high power dissipation
c) High noise creation
d) It uses minimum number of transistors

Explanation: The disadvantage of RTL is its high power dissipation when the transistor is switched on by current flowing in the collector and base resistor. This requires that more current be supplied to and heat be removed from RTL circuits. In contrast, TTL circuits with “totem-pole” output stage minimize both of these requirements.

9. TTL circuits with “totem-pole” output stage minimize __________
a) The power dissipation in RTL
b) The time consumption in RTL
c) The speed of transferring rate in RTL
d) Propagation delay in RTL

Explanation: TTL circuits with “totem-pole” output stage minimize the power dissipation and heating effect in RTL.

10. The minimum number of transistors can be used by 2 input AND gate is __________
a) 2
b) 3
c) 4
d) 5