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circuit_design:2_diodes [2023/09/19 22:16] – mexleadmincircuit_design:2_diodes [2024/11/29 01:01] (aktuell) – [Bearbeiten - Panel] mexleadmin
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 In metals, electrons are free to move. If an external voltage is applied, they follow the potential difference to the positive electrode: current flows. In insulators, on the other hand, the electrons are firmly bound to the atomic trunks. If a voltage is applied, they can at best be polarized. No current flows. In metals, electrons are free to move. If an external voltage is applied, they follow the potential difference to the positive electrode: current flows. In insulators, on the other hand, the electrons are firmly bound to the atomic trunks. If a voltage is applied, they can at best be polarized. No current flows.
  
-A semiconductor is a material whose conductivity lies between that of metals and that of insulators. The technologically most important example of a semiconductor is silicon. In the silicon crystal, the electrons are not freely movable as in metal, because they are bound to the atomic trunks. But a small supply of energy (e.g. thermal energy) is sufficient to release the electrons from the atoms. Then, when a voltage is applied, an electric current flows. This is called the **intrinsic conduction** (intrinsic conduction) of the semiconductor. When the electrons move around in the semiconductor, this is called **electron conduction**.+A semiconductor is a material whose conductivity lies between that of metals and that of insulators. The technologically most important example of a semiconductor is silicon. In the silicon crystal, the electrons are not freely movable as in metal, because they are bound to the atomic trunks. However, a small supply of energy (e.g. thermal energy) is sufficient to release the electrons from the atoms. Then, when a voltage is applied, an electric current flows. This is called the **intrinsic conduction** (intrinsic conduction) of the semiconductor. When the electrons move around in the semiconductor, this is called **electron conduction**.
  
 A hole with a positive electrical charge is created at the silicon atom from which the electron was removed. This is also called a defect electron. These holes can also move through the crystal lattice and thus generate an electric current. This is called **hole conduction**. Hole conduction can be thought of as a hole being filled by an electron from the neighboring atom. However, this creates a hole in the neighboring atom. Effectively, such a hole has migrated from one atom to another, carrying with it a positive electric charge. \\  A hole with a positive electrical charge is created at the silicon atom from which the electron was removed. This is also called a defect electron. These holes can also move through the crystal lattice and thus generate an electric current. This is called **hole conduction**. Hole conduction can be thought of as a hole being filled by an electron from the neighboring atom. However, this creates a hole in the neighboring atom. Effectively, such a hole has migrated from one atom to another, carrying with it a positive electric charge. \\ 
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 ===== 2.3 Special diodes ===== ===== 2.3 Special diodes =====
  
-So far the silicon PN diode and the Z-diode were discussed. Additionally, other diodes are available for various applications. In the following, the most important ones will be briefly described.+So far the silicon PN diode and the Z-diode have been discussed. Additionally, other diodes are available for various applications. In the following, the most important ones will be briefly described.
  
-==== 2.3.1 Diodes for Electic Applications ====+==== 2.3.1 Diodes for Electric Applications ====
  
 ==== Germanium diode ==== ==== Germanium diode ====
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 <panel type="info" title="Exercise 2.1.7 Circuit with multiple diodes II"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 92%> <panel type="info" title="Exercise 2.1.7 Circuit with multiple diodes II"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 92%>
  
-The following simulation includes multiple diodes. Assume a simple diode model (the forward voltage drop is $V_F=0.7~\rm V$ and constant). The source voltage shall be $U0 = 4~\rm V$.+The following simulation includes multiple diodes. Assume a simple diode model (the forward voltage drop is $V_F=0.6~\rm V$ and constant). The source voltage shall be $U0 = 4~\rm V$.
  
 Calculate the currents through $D1$, $R1$, and $R2$. Calculate the currents through $D1$, $R1$, and $R2$.
  
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 ====== Study Questions ======  ====== Study Questions ====== 
 === For self-study ===  === For self-study === 
-  * On a U-I diagram, draw the characteristic of an ideal diode and a real silicon diode and explain the differences.+  * On a U-I diagram, draw the characteristics of an ideal diode and a real silicon diode and explain the differences.
   * What is meant by N-doped and P-doped?    * What is meant by N-doped and P-doped? 
   * How does a junction form inside the diode?    * How does a junction form inside the diode? 
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 === with answers ===  === with answers === 
  
-<quizlib id="quiz" rightanswers="[['a1'],['a0', 'a1', 'a2', 'a3'], ['a1', 'a3', 'a5'], ['a1', 'a2', 'a3'], ['a0', 'a1', 'a2', 'a3'], ['a0', 'a1']" submit="Check answers"> +<WRAP hide> <quizlib id="dummy" rightanswers="[[]]" submit="x"></quizlib> Only necessary to eliminate the score bar... </WRAP> 
-  + 
-<question title="Which of the following statement(s) is/are correct?" type="checkbox"> +<WRAP column half> 
 +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
 +<quizlib id="quiz1" rightanswers="[['a1']]" submit="check answers"> 
 +<question title="Which of the following statement(s) for real diodes is/are correct?" type="checkbox"> 
 P-doping produces quasi-free electrons|  P-doping produces quasi-free electrons| 
-Conductivity in semiconductors happens via conduction and valence band| +Conductivity in semiconductors happens via the conduction band and valence band| 
 The diode blocks at any negative voltage (reverse voltage).|   The diode blocks at any negative voltage (reverse voltage).|  
 The diode can be modeled as a voltage source and capacitor The diode can be modeled as a voltage source and capacitor
-</question> +</question></quizlib></WRAP></WRAP></panel> 
- + 
 +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
 +<quizlib id="quiz2" rightanswers="[['a0', 'a1', 'a2', 'a3']]" submit="check answers">
 <question title="On which physical properties does the forward voltage $U_S$ depend?" type="checkbox">  <question title="On which physical properties does the forward voltage $U_S$ depend?" type="checkbox"> 
 temperature|  temperature| 
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 LED color|  LED color| 
 breakdown voltage of the Z-diode  breakdown voltage of the Z-diode 
-</question> +</question></quizlib></WRAP></WRAP></panel> 
- + 
 +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
 +<quizlib id="quiz3" rightanswers="[['a1', 'a3', 'a5']]" submit="check answers">
 <question title="Which statement(s) about the junction is/are correct?" type="checkbox">  <question title="Which statement(s) about the junction is/are correct?" type="checkbox"> 
 There is no electric field in the junction|  There is no electric field in the junction| 
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 The junction is enlarged in the Schottky diode compared to the PN diode| The junction is enlarged in the Schottky diode compared to the PN diode|
 The junction forms a capacitor  The junction forms a capacitor 
-</question> +</question></quizlib></WRAP></WRAP></panel> 
- + 
 +</WRAP><WRAP column half> 
 +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
 +<quizlib id="quiz4" rightanswers="[['a1', 'a2', 'a3']]" submit="check answers"> 
 +<question title="The forward voltage ..." type="checkbox">  
 +... for silicon is fixed about 0.6 ... 0.7 V|  
 +... serves to allow electrons to cross the bandgap|  
 +... depends on the current range under consideration|  
 +... is smaller for germanium diodes than for silicon diodes.  
 +</question></quizlib></WRAP></WRAP></panel> 
 + 
 +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
 +<quizlib id="quiz5" rightanswers="[['a0', 'a1', 'a2', 'a3']]" submit="check answers">
 <question title="Statements about the conduction/valence band" type="checkbox">  <question title="Statements about the conduction/valence band" type="checkbox"> 
 Photon capture can move electrons from the conduction band to the valence band|  Photon capture can move electrons from the conduction band to the valence band| 
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 A donor creates one or more quasi-free electrons|  A donor creates one or more quasi-free electrons| 
 The band gap indicates the maximum energetic distance between the conduction and valence bands  The band gap indicates the maximum energetic distance between the conduction and valence bands 
-</question> +</question></quizlib></WRAP></WRAP></panel> 
-  + 
-<question title="The forward voltage ..." type="checkbox">  +<panel type="info" title="Exercise - Quiz"> <WRAP group><WRAP column 2%>{{fa>pencil?32}}</WRAP><WRAP column 88%> 
-... for silicon is about 0.6 ... 0.7 V|  +<quizlib id="quiz6" rightanswers="[['a0', 'a1']]" submit="check answers">
-... serves to allow electrons to cross the bandgap|  +
-... depends on the current range under consideration|  +
-... is smaller for germanium diodes than for silicon diodes.  +
-</question> +
- +
 <question title="The forward current ..." type="checkbox">  <question title="The forward current ..." type="checkbox"> 
 ... Is dependent on the temperature|  ... Is dependent on the temperature| 
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 ... is logarithmic concerning the forward voltage|  ... is logarithmic concerning the forward voltage| 
 ... depends on the reverse voltage  ... depends on the reverse voltage 
-</question>  +</question></quizlib></WRAP></WRAP></panel> 
-</quizlib>+</WRAP>