Introduction to Digital Logic Gates

Logic Doors are circuits that allow us to perform logical operations by installing special electronic circuits with the desired number of logic variable inputs. At this point, the logistics doors are used to create combinational, sequential circuits. Today, the logistics doors that we can obtain from the market are usually available in 2 basic families or forms. The first will be TTL, which means Transistor-Transistor Logic. One example of this will be the 7400 series. In addition, another technology is CMOS. Examples of CMOS include 4000 series integrations.

To summarize this topic briefly:

Integrated with TTL technology, they include NPN and PNP type bipolar jonction transistors. Integrateds with CMOS technology include MOSFET or JFET type Field Effective Transistors. But it's also important to remember that we don't necessarily need to use integrated ones with these technologies to have a simple logistics door. In this case, diode, transistor and resistance style simple circuit elements will work for us to produce the logistics doors. Of course, this style of use is much less preferred today than in the CMOS family.
In addition to this issue, another important issue will be related to the way these integrations are named. Today, integrated circuits contain a lot of naming types. Another will depend on the transistor and the number of doors they contain. To give an example: a simple "OR" door can contain only a few transistors, while a more complex integrated can contain thousands of transistors. The general classification will be as follows:

  1. Small Scale Integration /Small Scale Integration (SSI)
  2. Medium Scale Integration (MSI)
  3. Large Scale Integration (LSI)
  4. Very Large Scale Integration (VLSI)
  5. Super Large Scale Integration /Super-Large Scale Integration (SLSI)
  6. Ultra-Large Scale Integration / Ultra-Large Scale Integration (ULSI)

Logistics Doors

Logistics Doors are the basic building block where all electronic circuits and microprocessor-based systems are made. Logic gates perform AND, OR and NOT logical operations on binary numbers in general. Only two voltage levels are allowed in digital electronics. These are 1 and 0 respectively, but when we do research, this can come up with many other terms. These are concepts such as Logistics "1" and Logistics "0", HIGH and LOW. As long as we pay attention to them, we are unlikely to make a mistake. introduction to logic gates In most logic gates, logic levels such as "0" or LOW represent zero voltage (0V) or soil. On the contrary, it represents a higher voltage value such as +5V in case it is "1". TTL integrateds with standard TTL technology have an unidentified input and output voltage range. These consist of the area between Logistics "1" and Logistics "0". introduction to logic gates From the above image, it is very easily understood at what voltage values the undefined areas of the integrateds of TTL technology are. Another important thing at this point is that voltage levels change in technologies such as CMOS and TTL. Let's take a look at it with an image. introduction to logic gates

Sample TTL Logistics Door Circuit

In this example, a simple AND NOT door circuit design is seen with transistors consisting of TTL family. As the picture shows, an input transistor with two (or more) emitter legs is used. Transistor 2's NPN switching transistor circuitry is reversed in single stage. To better understand this, we can value the inputs of our #1 transistor. introduction to logic gates At this point, as soon as one or both of the emitters representing the "A" and "B" inputs of Transistor 1 are connected to the logic level "0" (LOW), the basic current of Transistor 1 passes from the base/emitter connection to the soil (0V). In this way, it becomes saturated. As a result, transistor 2 causes the base leg to be connected to the soil (0V), so we see that transistor 2 has become CLOSED. Finally, the output value in Q is HIGH. So, as you can see, it's really easy to design a simple logistics door today. At this point, these logistics doors are designed ready and integrated in bulk. They play a very important role in today's digital electronics. Another similar circuit is the logistics doors made from the CMOS family. In them, the situation is as simple as in TTL's. However, there is one important issue that we should pay attention to here. We must bear in mind that CMOS logistics doors and devices work in a static-sensitive manner. Therefore, it is vital to work on antistatic, grounded machines or to wear an antistatic wristband. No matter where we are in life, the measure will always protect us from unsasy consequences, regardless of material or moral.