#Bjt transistor loops full

(The designation NPN or PNP informs the reader that the transistor is a bipolar junction type and the term NPN transistor is precise.) In the example of Figure 4.1 the transistor is an NPN type which means that the emitter is N type semiconductor, the base is P type semiconductor and the collector is N type semiconductor. Such transistors are referred to as NPN transistors. In the other form the emitter is N type semiconductor, the base is P type semiconductor and the collector is N type semiconductor. Such transistors are referred to as PNP transistors. In one form the emitter is P type semiconductor, the base is N type semiconductor and the collector is P type semiconductor. These three layers have been given the names emitter, base and collector.įigure 4.1 Simplified Drawing of a BJT With Supply VoltagesīJTs may be manufactured in either of two forms. A bipolar junction transistor consists of three layers of alternating semiconductor type. In this section we will study the internal physics of the BJT and try to understand how it does what it does.Ī simplified cross-section of a BJT is shown in Figure 4.1. We will be devoting much space in following sections to the circuits which permit the BJT to be used to control large currents. The nature of the BJT is such that the current in the second loop may be switched (turned on and off) or varied by an arbitrarily small amount.

#Bjt transistor loops full

Instead of using the full name every time, we will use the acronym BJT.Ī BJT will allow a small current in one circuit loop to control a much larger current (typically 100 times larger) in another circuit loop. The term 'transistor' is too imprecise for our purposes. Non-technical people are unaware that there are two major types of transistors, bipolar junction transistors and field effect transistors. Even people who don't know what a transistor looks like know the shortened name 'transistor'. That is, no doubt, why it is rarely called by that name. The full name of the tiny transistor is quite a mouthful. Such a large change was bound to start a revolution and it did.Ĥ.1 The Bipolar Junction Transistor (BJT). Even the very earliest of transistors occupied about 1/100 the volume of the average vacuum tube. But we digress - oh yes - the transistor. The demise of the vacuum tube has relegated this experiment to the dusty back shelves of history. The information available to the writer indicates that a prototype was actually constructed and tested. In fact, there was a little known attempt in the early 1960s to put vacuum tubes in an integrated package.

Some people might ask 'What about the integrated circuit?' The integrated circuit is just a more compact way of packaging circuitry.

The development of the transistor was the greatest single advancement in electronics since the development of the vacuum tube in the early part of the 20th century. Here is another small excerpt from my textbook.