was the first gain transistor obtained, invented in 1947 by J. Bardeen and W. Brattain. It consists of a germanium base on which they rest, close together, two metal spikes that form the emitter and collector. The emitter current is able to modulate the resistance "seen" in the collector, hence the name of "transfer resistor." It is based on surface effects, little known in his day. It is difficult to make (the points were adjusted by hand), fragile (one strike could move the ends) and noisy. But he lived with the junction transistor (W. Shockley, 1948) due to greater bandwidth. It has now disappeared.
The bipolar junction transistor, or BJT for its acronym in English, is made primarily on a single crystal of germanium, silicon or gallium arsenide, which are qualities of semiconductors, drivers and state between metals and insulators such as diamond. On the glass substrate, are contaminated in a very controlled three zones, two of which are the same type, NPN or PNP, leaving two junctions formed NP.
N zone with elements donor of electrons (negative charges) and the P side to accept or "holes" (positive charges). Normally used as acceptors P elements to Indio (In), aluminum (Al) or gallium (Ga) and donors N to Arsenic (As) or phosphorus (P).
PN junction configuration, result in PNP or NPN transistor, where the middle letter always corresponds to the characteristic of the base, and two to the emitter and collector, while the same type and opposite to the base, have different contamination between them (typically, the issuer is much more polluted than the collector).
The mechanism that represents the behavior of such contamination semiconductor depend on the geometry and the type associated with pollution technology (Gaseous diffusion, epitaxial, etc.) And the quantum behavior of the union.
also called junction field effect (JFET), was the first field effect transistor in practice. The material forms a bar-type silicon semiconductor N or P. At the end of the bar provides an ohmic contact, we have thus a field effect transistor type N in the most basic. If P two regions are distributed in a bar of N material and connected externally to each other, there will be a door. One of these contacrtos will call another supplier and drain. Applying a positive voltage between the drain and supplier and connecting door to the supplier, establish a current, which call drain current with zero bias. With a potential negative gate voltage which we call a bottleneck, ceases conduction in the channel.
The field-effect transistor, or FET for its acronym in English, which controls the current versus voltage, have high input impedance.
The phototransistors are sensitive to electromagnetic radiation at frequencies near that of light.
was the replacement of three-electrode thermionic valve or triode, the bipolar transistor was invented at Bell Laboratories U.S. December 1947 by John Bardeen , Walter Brattain yWillian Bradford, who were awarded the Nobel Prize for Physics in 1956.
At first they used bipolar transistors and then invented the so-called field effect transistors (FET). In the past, the current between the source and loss (collector) is controlled using an electric field (and lost output (collector) lower). Finally, it appeared the metal-oxide semiconductor FET (MOSFET). The MOSFET allowed an extremely compact design, necessary for highly integrated circuits (IC). Today most of the circuits are built with technology called CMOS (complementary metal-oxide semiconductor). CMOS technology is a design with two different MOSFET (n and p-channel MOSFET), which complement each other and consume very little current in no load operation.
The transistor consists of a substrate (usually silicon) and three parts artificially doped (contaminated with specific materials in specific quantities) that form two bipolar junctions, the issuer emitting carriers, the collector that receives or collection and the third, which is sandwiched between the first two, modulates the passage of these carriers ( base). Unlike the valves, the transistor is a current controlled device and obtained amplified current. In the design circuit transistors are considered an active element, unlike resistors, capacitors einductores that are passive. Its operation can only be explained by quantum mechanics.
In simple terms, the current flowing through the "collector" is amplified function that is injected into the "sender", but the transistor graduates only the current flowing through itself, whether from a current source continuously fed to the "base" to circulate the load by the "collector", according to the type of circuit is used. The amplification factor or gain achieved between base current and collector current, the transistor is called Beta. Other parameters to take into account and that are specific to each type of transistor are: Breakdown Voltage Collector Emitter, Base Emitter, Collector Base, Maximum power, heat dissipation, operating frequency, and several tables which are plotted various parameters such as base current, collector emitter voltage, base-emitter voltage, emitter current, etc. The three basic types of schemes use analog transistors are common emitter, common collector and common base.
post-transistor models described, the bipolar transistor (FET transistors, MOSFET, JFET, CMOS, VMOS, etc.) Do not use the current to be injected into the terminal "base" to modulate the emitter current or collector, but the voltage at the terminal door or gate control and graduates channel conductance between source and drain terminals. Thus, the output current in the load connected to the drain (D) will be amplified according to the voltage between the gate (Gate) and source (Source). Its operation is analogous to the triode, except that the equivalent triode gate, drain and source are grating, plate and cathode.
The field effect transistors, are those that have allowed large-scale integration we enjoy today, to have a rough idea can be made several thousand transistors interconnected per square centimeter in several layers.
This is the first of a series of photos taken at the central cemetery, had just resigned from the paint factory, the manager a bit tedious retrograde your personal way of seeing business, a fight that did not go to higher because not taking into account all the strategies proposed and evil genius overwhelmed I decided to walk, without thinking, reach the Central Cemetery and started taking photos with a small camera of 5 mega pixels, calm and end up creating an album that I really liked.
