1、Chapter 1BoylestadElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiodesThe diode is a 2-terminal device.A diode ideally conducts in only one direction.Electronic Devices and Circuit TheoryBoylest
2、ad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode CharacteristicsConduction RegionNon-Conduction RegionThe voltage across the diode is 0 V The current is infiniteThe forward resistance is defined as RF = VF / IFThe diode acts like a sho
3、rtAll of the voltage is across the diodeThe current is 0 AThe reverse resistance is defined as RR = VR / IRThe diode acts like openElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummarySemiconductor Mat
4、erialsMaterials commonly used in the development of semiconductor devices:Silicon (Si)Germanium (Ge)Gallium Arsenide (GaAs)Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDopingThe electrical char
5、acteristics of silicon and germanium are improved by adding materials in a process called doping.There are just two types of doped semiconductor materials:n-type p-typen-type materials contain an excess of conduction band electrons.p-type materials contain an excess of valence band holes.Electronic
6、Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 Summaryp-n JunctionsThe result is a p-n junctionOne end of a silicon or germanium crystal can be doped as a p-type material and the other end as an n-type material.El
7、ectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 Summaryp-n JunctionsThe electrons in the n-type material migrate across the junction to the p-type material (electron flow). The result is the formation of a
8、 depletion region around the junction.Electron migration results in a negative charge on the p-type side of the junction and a positive charge on the n-type side of the junction.At the p-n junction, the excess conduction-band electrons on the n-type side are attracted to the valence-band holes on th
9、e p-type side.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsA diode has three operating conditions:No biasReverse biasForward biasElectronic Devices and Circuit TheoryB
10、oylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsNo external voltage is applied: VD = 0 V There is no diode current: ID = 0 AOnly a modest depletion region existsNo BiasElectronic Devices and Circuit TheoryBoy
11、lestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsExternal voltage is applied across the p-n junction in the opposite polarity of the p- and n-type materials.Reverse BiasElectronic Devices and Circuit TheoryBoyle
12、stad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsReverse BiasThe holes in the p-type material are attracted toward the negative terminal of the voltage source.The reverse voltage causes the depletion region to wid
13、en.The electrons in the n-type material are attracted toward the positive terminal of the voltage source.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsForward BiasExter
14、nal voltage is applied across the p-n junction in the same polarity as the p- and n-type materials.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Operating ConditionsForward BiasThe electro
15、ns and holes have sufficient energy to cross the p-n junction.The forward voltage causes the depletion region to narrow.The electrons and holes are pushed toward the p-n junction.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458
16、All Rights ReservedCh.1 SummaryActual Diode CharacteristicsNote the regions for no bias, reverse bias, and forward bias conditions.Carefully note the scale for each of these conditions.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey
17、07458 All Rights ReservedCh.1 SummaryMajority and Minority CarriersTwo currents through a diode:The minority carriers in p-type materials are electrons.Majority CarriersThe majority carriers in n-type materials are electrons.The majority carriers in p-type materials are holes.Minority CarriersThe mi
18、nority carriers in n-type materials are holes.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryZener RegionAt some point the reverse bias voltage is so large the diode breaks down and the reverse c
19、urrent increases dramatically.The voltage that causes a diode to enter the zener region of operation is called the zener voltage (VZ).The Zener region is in the diodes reverse-bias region.The maximum reverse voltage that wont take a diode into the zener region is called the peak inverse voltage or p
20、eak reverse voltage.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryForward Bias VoltageThe point at which the diode changes from no-bias condition to forward-bias condition occurs when the electr
21、ons and holes are given sufficient energy to cross the p-n junction. This energy comes from the external voltage applied across the diode.The forward bias voltage required for a:gallium arsenide diode 1.2 Vsilicon diode 0.7 Vgermanium diode 0.3 VElectronic Devices and Circuit TheoryBoylestad 2013 by
22、 Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryTemperature EffectsIt reduces the required forward bias voltage for forward-bias conduction.It increases the amount of reverse current in the reverse-bias condition.It increases maximum reverse bias ava
23、lanche voltage.As temperature increases it adds energy to the diode. Germanium diodes are more sensitive to temperature variations than silicon or gallium arsenide diodes.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Righ
24、ts ReservedCh.1 SummaryResistance LevelsDC (static) resistanceAC (dynamic) resistanceAverage AC resistanceSemiconductors react differently to DC and AC currents. There are three types of resistance:Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River
25、, New Jersey 07458 All Rights ReservedCh.1 SummaryDC (Static) ResistanceFor a specific applied DC voltage (VD) the diode has a specific current (ID) and a specific resistance (RD).DDDIVRElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey
26、 07458 All Rights ReservedCh.1 SummaryAC (Dynamic) ResistanceThe resistance depends on the amount of current (ID) in the diode.The voltage across the diode is fairly constant (26 mV for 25C).rB ranges from a typical 0.1 for high power devices to 2 for low power, general purpose diodes. In some cases
27、 rB can be ignored.BDdrImV26 r rdIn the forward bias region:In the reverse bias region:The resistance is effectively infinite. The diode acts like an open.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1
28、SummaryAverage AC ResistanceAC resistance can be calculated using the current and voltage values for two points on the diode characteristic curve.pt. to pt. IV rddavElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights Res
29、ervedCh.1 SummaryDiode Equivalent CircuitElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode CapacitanceWhen reverse biased, the depletion layer is very large. The diodes strong positive and neg
30、ative polarities create capacitance (CT). The amount of capacitance depends on the reverse voltage applied.When forward biased, storage capacitance or diffusion capacitance (CD) exists as the diode voltage increases. Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, In
31、cUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryReverse Recovery Time (trr)Reverse recovery time is the time required for a diode to stop conducting when switched from forward bias to reverse bias.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, I
32、ncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Specification Sheets1. Forward Voltage (VF) at a specified current and temperature2. Maximum forward current (IF) at a specified temperature3. Reverse saturation current (IR) at a specified voltage and temperature4. Reverse
33、voltage rating, PIV or PRV or V(BR), at a specified temperature5. Maximum power dissipation at a specified temperature6. Capacitance levels7. Reverse recovery time, trr8. Operating temperature rangeDiode data sheets contain standard information, making cross-matching of diodes for replacement or des
34、ign easier.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode Symbol and PackagingThe anode is abbreviated AThe cathode is abbreviated K Electronic Devices and Circuit TheoryBoylestad 2013 by P
35、earson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode TestingDiode checkerOhmmeterCurve tracerDiodes are commonly tested using one of these types of equipment:Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Sad
36、dle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode CheckerGallium arsenide 1.2 VSilicon diode 0.7 VGermanium diode 0.3 VMany digital multimeters have a diode checking function. The diode should be tested out of circuit.A normal diode exhibits its forward voltage:Electronic Devices and
37、Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryOhmmeterAn ohmmeter set on a low Ohms scale can be used to test a diode. The diode should be tested out of circuit.Electronic Devices and Circuit TheoryBoylestad 2013 by P
38、earson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryCurve TracerA curve tracer displays the characteristic curve of a diode in the test circuit. This curve can be compared to the specifications of the diode from a data sheet.Electronic Devices and Circuit
39、TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryOther Types of DiodesZener diodesLight-emitting diodesDiode arraysThere are several types of diodes besides the standard p-n junction diode. Three of the more common are:Electroni
40、c Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryZener DiodeA Zener diode is one that is designed to safely operate in its zener region; i.e., biased at the Zener voltage (VZ). Common zener diode voltage ra
41、tings are between 1.8 V and 200 VElectronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryLight-Emitting Diode (LED)An LED emits light when it is forward biased, which can be in the infrared or visible spe
42、ctrum. The forward bias voltage is usually in the range of 2 V to 3 V.Electronic Devices and Circuit TheoryBoylestad 2013 by Pearson Higher Education, IncUpper Saddle River, New Jersey 07458 All Rights ReservedCh.1 SummaryDiode ArraysMultiple diodes can be packaged together in an integrated circuit (IC).Common AnodeCommon CathodeA variety of diode configurations are available.
