La edicion anterior de Electronica: Teoria de Circuitos y Dispositivos Electronicos requirio varios cambios significativos en cuanto a pedagogia y contenido. Esta edicion fue mas selectiva en las adecuaciones que se debian hacer. Los titulos de los capitulos no se modificaron y se agrego un numero limitado de secciones nuevas. Los cambios se efectuaron sobre todo para mejorar la forma en que se presenta el material mas importante y para mantener actualizado el contenido.
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For information regarding permission s , write to: Rights and Permissions Department. Copper has 20 orbiting electrons with only one electron in the outermost shell. The fact that the outermost shell with its 29th electron is incomplete subshell can contain 2 electrons and distant from the nucleus reveals that this electron is loosely bound to its parent atom.
The application of an external electric field of the correct polarity can easily draw this loosely bound electron from its atomic structure for conduction. Both intrinsic silicon and germanium have complete outer shells due to the sharing covalent bonding of electrons between atoms.
Electrons that are part of a complete shell structure require increased levels of applied attractive forces to be removed from their parent atom. Intrinsic material: an intrinsic semiconductor is one that has been refined to be as pure as physically possible. That is, one with the fewest possible number of impurities.
Negative temperature coefficient: materials with negative temperature coefficients have decreasing resistance levels as the temperature increases. Covalent bonding: covalent bonding is the sharing of electrons between neighboring atoms to form complete outermost shells and a more stable lattice structure.
An n-type semiconductor material has an excess of electrons for conduction established by doping an intrinsic material with donor atoms having more valence electrons than needed to establish the covalent bonding. The majority carrier is the electron while the minority carrier is the hole. A p-type semiconductor material is formed by doping an intrinsic material with acceptor atoms having an insufficient number of electrons in the valence shell to complete the covalent bonding thereby creating a hole in the covalent structure.
The majority carrier is the hole while the minority carrier is the electron. A donor atom has five electrons in its outermost valence shell while an acceptor atom has only 3 electrons in the valence shell.
Majority carriers are those carriers of a material that far exceed the number of any other carriers in the material. Minority carriers are those carriers of a material that are less in number than any other carrier of the material. Same basic appearance as Fig. For forward bias, the positive potential is applied to the p-type material and the negative potential to the n-type material.
For most applications the silicon diode is the device of choice due to its higher temperature capability. Ge typically has a working limit of about 85 degrees centigrade while Si can be used at temperatures approaching degrees centigrade.
Silicon diodes also have a higher current handling capability. Germanium diodes are the better device for some RF small signal applications, where the smaller threshold voltage may prove advantageous. From 1. Usually, however, technology only permits a close replica of the desired characteristics. The most important difference between the characteristics of a diode and a simple switch is that the switch, being mechanical, is capable of conducting current in either direction while the diode only allows charge to flow through the element in one direction specifically the direction defined by the arrow of the symbol using conventional current flow.
From Fig. The transition capacitance is due to the depletion region acting like a dielectric in the reverse- bias region, while the diffusion capacitance is determined by the rate of charge injection into the region just outside the depletion boundaries of a forward-biased device.
Both capacitances are present in both the reverse- and forward-bias directions, but the transition capacitance is the dominant effect for reverse-biased diodes and the diffusion capacitance is the dominant effect for forward-biased conditions. As the magnitude of the reverse-bias potential increases, the capacitance drops rapidly from a level of about 5 pF with no bias. For reverse-bias potentials in excess of 10 V the capacitance levels off at about 1. Using the bottom right graph of Fig.
For germanium it is a 6. For the high-efficiency red unit of Fig. Levels of part c are reasonably close but as expected due to level of applied voltage E. The threshold voltage of 0. Since all the system terminals are at 10 V the required difference of 0. Vdc 2V Positive half-cycle of vi: Voltage-divider rule: 2. Voltage-divider rule: 2. However, vo is connected directly through the 2. For the positive region of vi: The right Si diode is reverse-biased.
For the negative region of vi: The left Si diode is reverse-biased. Using the ideal diode approximation the vertical shift of part a would be V rather than Using the ideal diode approximation would certainly be appropriate in this case.
Solution is network of Fig. Network of Fig. The maximum level of I Rs will in turn determine the maximum permissible level of Vi. A bipolar transistor utilizes holes and electrons in the injection or charge flow process, while unipolar devices utilize either electrons or holes, but not both, in the charge flow process.
Forward- and reverse-biased. The leakage current ICO is the minority carrier current in the collector. The separation between IB curves is the greatest in this region. Output characteristics: Curves are essentially the same with new scales as shown. Input characteristics: Common-emitter input characteristics may be used directly for common-collector calculations. The levels are higher for hfe but note that VCE is higher also. As the reverse-bias potential increases in magnitude the input capacitance Cibo decreases Fig.
In other words, the expected increase due to an increase in collector current may be offset by a decrease in VCE. S VBE : The voltage-divider configuration is more sensitive than the other three which have similar levels of sensitivity.
In general, the voltage-divider configuration is the least sensitive with the fixed-bias the most sensitive. In total the voltage-divider configuration is considerably more stable than the fixed-bias configuration. Use approximate approach: 8. RL Vi Zi For each stage: 6. Log-log scale! The collector characteristics of a BJT transistor are a plot of output current versus the output voltage for different levels of input current.
The drain characteristics of a JFET transistor are a plot of the output current versus input voltage. For the BJT transistor increasing levels of input current result in increasing levels of output current. For JFETs, increasing magnitudes of input voltage result in lower levels of output current.
The spacing between curves for a BJT are sufficiently similar to permit the use of a single beta on an approximate basis to represent the device for the dc and ac analysis.
VCsat and VP define the region of nonlinearity for each device. For a p-channel JFET, all the voltage polarities in the network are reversed as compared to an n-channel device. In addition, the drain current has reversed direction. From Fig 6. In the depletion MOSFET the channel is established by the doping process and exists with no gate-to-source voltage applied. As the gate-to-source voltage increases in magnitude the channel decreases in size until pinch-off occurs.
The enhancement MOSFET does not have a channel established by the doping sequence but relies on the gate-to-source voltage to create a channel. The larger the magnitude of the applied gate-to-source voltage, the larger the available channel.
VP Either the JFET is defective or an improper circuit connection was made. Possible short-circuit from D-S.
Draw a straight line through the two points located above, as shown below. Add 0. In fact, all levels of Av are divided by to obtain normalized plot.
The resulting curve should be quite close to that plotted above. From example 9. V1 12 V Circuit operates as a window detector. See section A line or lines onto which data bits are connected.
ISBN 13: 9786074422924
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