Digital Circuits & Design, 1st Education by Pearson

7.4 | Chapter 7

Two inverters, connected in series with feedback (Figure 7.6), are used to produce two

stable states i.e. either logic-0 or logic-1 state. The line connecting the output of inverter-II

back to the input of inverter-I is called feedback line.

O

1

Input

(I)

O

2

O

3

Feedback

I II

FIGURE 7.6 | Basic latch

TABLE 7.1 | Truth table

I O

1

O

2

O

3

0 0 1 0

1 1 0 1

Let Input, I is 0 then output of inverter-I, O

2

becomes logic-0 (Table 7.1). Output, O

2

acts

as input for inverter-II and produces logic-1 state. Since, output, O

3

of inverter-II acts input,

O

1

, of inverter-I. So, output, O

2

of inverter-I and output, O

3

of inverter-II remains same. Two

stable ...