Diode transistor logic gate, Electrical Engineering

Assignment Help:

A circuit realization of a NAND gate will now be developed. By connecting NAND gates together in various ways, one can synthesize other gates and flip-flops. Thus in principle, a single NAND gate circuit, repeated many times, would be sufficient to build up digital systems. One possible NAND gate circuit is shown in Figure, in which it can have asmany inputs as desired (indicated by the dashed-line input C), and typical values of VCC = 5V, RA = 2k, RC = 5k, and β = 50. We shall now consider the two inputs A and B that are quite adequate for our discussion,with the high range defined to be 4 to 5Vand the lowrange defined to be 0 to 0.5V.

555_Diode Transistor Logic Gate.png

While the input voltages vA and vB are constrained to lie inside the high or low range of the allowed voltage ranges, the resulting output voltage vF is supposed to be inside the high or low range as well. For different combinations of vA and vB, we need to find vF. Since the circuit consists of no less than five nonlinear circuit elements (DA, DB, D1, D2, and T1), an approximation technique is used for analysis, while taking the voltage across a current-carrying forward-biased pn junction to be 0.7 V. The reader may have realized that it is not obvious at the start which diodes are forward-biased and which are reverse-biased. Hence a guessing procedure is used in which a guess is made and checked for self-consistency.

Let us start by letting vA = vB = 0, in which case a probable current path is from VCC down through RA and through inputs A and B. Since this guess implies current flow through DA and DB in the forward direction, wemay guess that the voltage at X is 0.7 V. There is also a current path from X down to ground through D1 and D2 and the base-emitter junction of the transistor. Even though the sign of the guessed voltage is correct to forward-bias these three junctions, its magnitude of 0.7 V is insufficient since 2.1 V (or 3 × 0.7) is needed to make current flow through this path.


Related Discussions:- Diode transistor logic gate

Machine-tool process to drill or punch holes, Q. Explain Machine-tool proce...

Q. Explain Machine-tool process to drill or punch holes? Figure depicts an elementary system, including the input, digital processor, drill-positioning mechanism, and sampled-d

Discuss the need of peripheral component interconnect bus, Discuss the need...

Discuss the need of PCI bus. Peripheral Component Interconnect (PCI): It was developed by Intel and introduced in 1993 year. This is geared particularly to fifth- and sixth-

Explain analog communication system, Q. Explain Analog communication system...

Q. Explain Analog communication system? Analog signals in an analog communication system can be transmitted directly via carrier modulation over the communication channel and d

Obtain the time domain functions, Let ω = 2π × 60 rad/s corresponding to a ...

Let ω = 2π × 60 rad/s corresponding to a frequency of 60 Hz. (a) Consider v(t) = 100 √2 cos(ωt + 30°) V and i(t) = 10 √2 sin(ωt + 30°) A. Find the corresponding phasors ¯V and ¯

Determine the angular frequency, Q. For given asymptotic Bode plots. (a)...

Q. For given asymptotic Bode plots. (a) Find ¯H 1 , ¯H 2 , and ¯H 3 at ω = 5 rad/s. (b) At what angular frequency ω is the magnitude of ¯H 4 (jω) one-half of the magnitude o

Introduction to electronics, Explain the difference between a microprocesso...

Explain the difference between a microprocessor and an embedded microcontroller

Define the signals in time domain, Define the Signals in Time Domain? T...

Define the Signals in Time Domain? The time domain is the type of visualization that most people are familiar with. This method shows variations of a signal with time. The most

Working with various instructions using debug, The purpose of this experime...

The purpose of this experiment is to introduce you to a powerful 80x86 assembly/machine language utility called DEBUG. Preparing Your DEBUG Environment If you have an older

What do you mean by interference, Q. What do you mean by interference? ...

Q. What do you mean by interference? An information-bearing signal often becomes contaminated by externally generated interference and noise and/or by internally generated nois

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd