Transistor as a voltage amplifier 5.pdf

General Physics fifth lecture Transistor as a voltage amplifier Dr.Ameen Alwan first stage Department of Bio Chemistry Al-Mustaqbal University 2023- 2024 Magnified circuits:(‫) اﻟﺪواﺋﺮ اﻟﻤﻜﺒﺮة‬Despite the rapid progress of integrated circuits, the...

General Physics fifth lecture Transistor as a voltage amplifier Dr.Ameen Alwan first stage Department of Bio Chemistry Al-Mustaqbal University 2023- 2024 Magnified circuits:(‫) اﻟﺪواﺋﺮ اﻟﻤﻜﺒﺮة‬Despite the rapid progress of integrated circuits, the bipolar transistor is still and will remain as an important and necessary single component in electronic circuits, especially in solving problems of compatibility between the inputs and exits of integrated circuits. The transistor is frequently used in different magnified circuits, and they are divided into D.C voltage amplifiers ‫ﻣﻜﺒﺮ اﻟﻔﻮﻟﺘﯿﺔ اﻟﻤﺴﺘﻤﺮة‬ "Alternating voltage amplifiers" are used to amplify frequency signals from the beginning of the frequency ladder to the band above the gigahertz, while "constant voltage amplifiers" are used to transmit voltage and are without components affected by the frequency capacitor and coil. "Power amplifiers" (with high combined currents) are used for high-power signals, while "interlock amplifiers" (high-current, fast-engaged) are used to direct a square-shaped voltage signal (i.e. also in digital circuits such as a computer). Look fig. 1 Fig. 1 Constant voltage amplifier The magnification factor of the constant voltage is small and much less than the alternating voltage and with the same amplifier, and it is only left to raise the magnification factor to connect a number of successive phases. This is where one of the important problems of electronics begins, which is "fitting",‫ ﻣﻼﺋﻤﺔ‬since when the magnification stages follow one after the other, there are differences in energy suitability between the input and the outlet, in addition to the thermal effects that affect the "operating point." Alternating voltage amplifier:‫ﻣﻜﺒﺮ اﻟﻔﻮﻟﺘﯿﺔ اﻟﻤﺘﻨﺎوﺑﺔ‬ Alternating voltage amplifiers are classified into two types: the first is the "broadband amplifier", Which magnifies a wide range of frequencies, i.e. such as the "audio amplifier", which magnifies all the frequencies that the human ear can hear (from 20 Hz to 20 Elo Hz, approximately 20 thousand Hz), and the second type is the "frequency limiter amplifier" and what the name is known, it magnifies a thin beam of 700 MHz, for example, and is used in high frequency. Look fig. 2 Fig. 1 ultra-voltage amplifier For the wideband amplifier (20 Hz to 20 kHz), that is, during the design or calculation two frequencies must be taken into account "lower limit of frequency" and "upper limit of frequency". Note\\But we can know its type (PNP, NPN) and that: If the positive pole of the meter is present on the base when it gives a low resistance with the collector and the emitter, the transistor is the type (NPN). If the negative pole of the meter is present on the base when it gives a low resistance with the collector and the emitter, the transistor is the type (PNP).