Resistor-Transistor Logic (RTL)

Resistor-Transistor Logic (RTL):

RTL circuit:

        RTL circuit consist of resistor and transistor.

          2-input RTL NOR gate and has emitters of both transistor are connected to a common ground and collector of both transistors are tied through a supply voltage Vcc.

The resistor is known as passive pull-up resistor.

Circuit operation:

A	B	Y
0	0	1
0	1	0
1	0	0
1	1	0

             In the RTL gate the input voltage corresponding to LOW level is required to be low enough for the corresponding transistor to be cut-off.

Similarly, the input voltage corresponding to HIGH level should be high enough to derive the corresponding transistor to saturation.

When both the input are low transistor Q1 and Q2 are cut-off and the output is HIGH.

A HIGH level on any input voltage corresponding transistor to saturation causing the output to go LOW.

Specification:

           RTL gates have poor noise margin, poor fan-out capability, low speed and high power dissipation.

Parameter	value
Propagation delay	12 nsec
Power dissipation	30-100 mW
Noise Margin	0.2
Fan-out	4

 

 

Digital logic circuit

Unit 1

Representation of number of different Radix

Conversion of number system

Binary Arithmetic

Binary codes

Error detection and correction codes

Characteristics of digital logic families

RTL

DTL

TTL

MOS Families

ECL

Comparison between families