Circuit Structures:In general, the functions of different stages of any gate are identical to those of inverter and NAND gates. It is good to recall, though, that many logic functions are implemented by the real connections made in a circuit structure. Recall, for illustration, the input phase of the inverter.The input transistor T1 acts as a current steering and amplifying phase. It is T2 which essentially functions the inversion. Therefore, in TTL structures, the configuration of transistors shown in figure below will always execute an inverting operation.
Figure: Inverting Structure
Remember, as well, the input structure of NAND gate. The input combination of multiple emitters functions a logical AND operation on inputs in the current steering mechanism. This is T2 which performs the inversion to provide an overall NAND operation.
Figure: ‘AND’ Structure
Let consider a final structure where two transistors are basically joined in parallel with a common load as shown in figure below. Principally, if either transistor is turned on, it will conduct and draw current via the load making the output go low. Only whenever both transistors are OFF, tending to make the output HI individually, will the output really be HI. This is an AND operation and the connection is termed to as a wired and connection. This circuit structure is equal to two inverters on the input of an AND gate that is logically equivalent to an NOR structure as can be seen from the figure and table shown below:
Figure: ‘OR’ Structure
Figure: Logical Equivalent of ‘Or’ ing (NOR) Structure
Standard TTL 74-Series Logic Gates:The figures below show complete circuit schematic diagrams for some of the fundamental logic gates in the Standard TTL 7400 series with usual component values comprised. The diodes shown on the inputs are protection diodes for input transistors. Such prevent negative voltages being developed at input terminals due to ringing on inductive lines employed to join gates altogether. Large, negative spikes at input would tend to over bias the base-emitter junction of input transistors and destroy them. Such voltages are clamped to a diode drop by input protection diodes.A) Inverter 7404
B) NAND Gate 7400 C) NOR Gate 7402Transistor pairs T1 + T2 and T5 + T6 form the inverters to inputs. The parallel connection of the collectors of T2 and T6 gives a wired AND function as previously explained. The output phase, T3 + T4, is as before. This gives the function:
a‾.b‾ = (a+b)‾
That is the NOR operation.
D) AND-OR-INVERT Gate 7451:This is really a combination of NAND and NOR gate structures. The multiple emitter input transistors T1 and T5 execute an AND function on their individual inputs. The following transistors T2 and T6 invert the AND functions. The parallel connection of T2 and T6 gives the wired AND function as in NOR gate. The overall condition is equivalent to that shown in figure below. The notable feature of this gate is that it permits Boolean functions to be implemented in sum-of-products form in a single gate with a propagation delay equivalent to that of an inverter. The inversion of function can be corrected for by implementing 0 terms of function instead of 1s.
Figure: Logical Equivalent of AND-OR-INVERT Structure
E) EXCLUSIVE-OR Gate 7486:This can be seen that T1 to T6 of this structure is similar to that of A-O-I Gate and executes the same logical operation. Transistors T7 + T8 and T9 + T10 just comprise an inversion on one pair of inputs. The circuit is logically equal to the structure shown in figure below that is seen to offer an exclusive-OR operation.
Figure: Logical Equivalent of Exclusive OR Gate Structure
Figure: Schematic Diagram of 7404 Standard TTL Inverter
Figure: Schematic Diagram of 7400 Standard TTL NAND Gate
Figure: Schematic Diagram of 7402 Standard TTL NOR Gate
Figure: Schematic Diagram of 7451 Standard TTL AND-OR-INVERT Gate
Figure: Schematic Diagram of 7486 Standard TTL EXCLUSIVE-OR Gate
Latest technology based Electrical Engineering Online Tutoring Assistance
Tutors, at the www.tutorsglobe.com, take pledge to provide full satisfaction and assurance in Electrical Engineering help via online tutoring. Students are getting 100% satisfaction by online tutors across the globe. Here you can get homework help for Electrical Engineering, project ideas and tutorials. We provide email based Electrical Engineering help. You can join us to ask queries 24x7 with live, experienced and qualified online tutors specialized in Electrical Engineering. Through Online Tutoring, you would be able to complete your homework or assignments at your home. Tutors at the TutorsGlobe are committed to provide the best quality online tutoring assistance for Electrical Engineering Homework help and assignment help services. They use their experience, as they have solved thousands of the Electrical Engineering assignments, which may help you to solve your complex issues of Electrical Engineering. TutorsGlobe assure for the best quality compliance to your homework. Compromise with quality is not in our dictionary. If we feel that we are not able to provide the homework help as per the deadline or given instruction by the student, we refund the money of the student without any delay.
theory and lecture notes of markov algorithms all along with the key concepts of universal model of computation, algorithm design, recurrent issues and troubles in markov programming, reverse the input string, double the input string, serial binary adder. tutorsglobe offers homework help, assignment help and tutor’s assistance on markov algorithms.
www.tutorsglobe.com offers area and volume of plane figures homework help, assignment help, online tutoring assistance, geometry mathematics solutions by online qualified tutor's help.
www.tutorsglobe.com offers parabola homework help, parabola assignment help, online tutoring assistance, general form of parabolas, standard form of parabolas math solutions by online qualified geometry mathematics tutor's help.
Theory and lecture notes of Benefits of Monopoly all along with the key concepts of Scale Economies, Research and Development, Regulating Monopoly, Two-tier Pricing, Rate-of-Return Regulation. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Benefits of Monopoly.
tutorsglobe.com ovulation and fate of the ovum assignment help-homework help by online functioning of female reproductive system tutors
www.tutorsglobe.com offers reversible addition reactions homework help, reversible addition reactions assignment help, online tutoring assistance, organic chemistry solutions by online qualified tutor's help.
Theory and lecture notes of Measures of Variation all along with the key concepts of Measures of variation, Range, Variance, Standard Deviation, Sum of Squares, Chebyshev's Theorem and Empirical Rule. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Measures of Variation.
tutorsglobe.com increase and decrease in demand assignment help-homework help by online theory of demand tutors
Elements of Group 15 tutorial all along with the key concepts of Occurrence, Extraction and Uses of group 15, General Characteristics of Group 15, Physical-Chemical Properties of group 15 elements and Allotropic Forms of Phosphorus
front panel control of cro - on - off: the on-off switch control employed to manage the cro in on-off position.
manufacture of hydrogen tutorial all along with the key concepts of manufacture through chemical means, manufacturing by electrolysis, properties of hydrogen, uses of hydrogen
tutorsglobe.com leaf hooks assignment help-homework help by online leaf modification tutors
Hydrometallurgy tutorial all along with the key concepts of meaning of hydrometallurgy, Processes of Hydrometallurgy and Advantages of Hydrometallurgy
Theory and lecture notes of all along with the key concepts of regression, homework help, assignment help, correlation & regression tutors. Tutorsglobe offers homework help, assignment help and tutor’s assistance on Theory of Regression.
Systematic Classification of Protozoa tutorial all along with the key concepts of The Flagellates, The Zooflagellates, The Amoebas, Nutrition of Amoeba, The Sporozoa, The Ciliates and Other Ciliated Protozoa
1941732
Questions Asked
3689
Tutors
1441757
Questions Answered
Start Excelling in your courses, Ask an Expert and get answers for your homework and assignments!!