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electrical_engineering_and_electronics_2:block11 [2026/06/02 00:47] – mexleadminelectrical_engineering_and_electronics_2:block11 [2026/06/10 03:08] (current) – mexleadmin
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 \] \]
 at a qualitative level. at a qualitative level.
-  * calculate simple diode operating points with a series resistor. 
-  * identify basic diode types such as universal diodes, Z-diodes, and LEDs. 
 </callout> </callout>
  
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 ===== Core content ===== ===== Core content =====
- 
-<callout> A nice introduction to the bipolar transistor can be found in [[http://eng.libretexts.org/Bookshelves/Materials_Science/Supplemental_Modules_(Materials_Science)/Materials_and_Devices/Bipolar_Junction_Transistor|libretexts]]. Some of the following passages, videos and pictures are taken from this introduction. </callout> 
  
 <WRAP><callout type="info" icon="true"> <WRAP><callout type="info" icon="true">
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 <WRAP> <WRAP>
 <panel type="default"> <panel type="default">
-<imgcaption sep_Res|sepcific resistance for selected conductors, semiconductors, and insulators.></imgcaption>+<imgcaption sep_Res|specific resistance for selected conductors, semiconductors, and insulators.></imgcaption>
 {{drawio>block11_specResistanceV02.svg}} {{drawio>block11_specResistanceV02.svg}}
 </panel> </panel>
Line 407: Line 403:
 ^ Symbol ^ Meaning ^ ^ Symbol ^ Meaning ^
 | \(I_{\rm S}(T)\) | reverse saturation current, strongly temperature-dependent  | | \(I_{\rm S}(T)\) | reverse saturation current, strongly temperature-dependent  |
-| \(m\) | emission coefficient, typically \(1\ldots 2\)  |+| \(m\) | emission coefficient, typically \(1\ldots 2\), material constant  |
 | \(U_{\rm T}\) | thermal voltage ($U_{\rm T}\approx 26~{\rm mV}$ at room temperature)  | | \(U_{\rm T}\) | thermal voltage ($U_{\rm T}\approx 26~{\rm mV}$ at room temperature)  |
 | \(k\) | Boltzmann constant  | | \(k\) | Boltzmann constant  |
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 \] \]
 </callout> </callout>
- 
-==== Operating point with a series resistor ==== 
- 
-A diode must usually be operated with a current-limiting element. 
- 
- 
-<WRAP> 
-<panel type="default"> 
-<imgcaption op_point_circuit|Circuit of Diode with Shunt resistor.></imgcaption> 
-{{drawio>op_point_circuit_v01.svg}} 
-</panel> 
-</WRAP> 
- 
-For the circuit in <imgref op_point_circuit> the loop equation is 
- 
-\[ 
-\begin{align*} 
-U_{\rm E} 
-= 
-U_R+U_{\rm D}. 
-\end{align*} 
-\] 
- 
-With the constant-voltage model, 
- 
-\[ 
-\begin{align*} 
-U_{\rm D}\approx U_{\rm TO}. 
-\end{align*} 
-\] 
- 
-Therefore 
- 
-\[ 
-\begin{align*} 
-I_{\rm D} 
-\approx 
-\frac{U_{\rm E}-U_{\rm TO}}{R}. 
-\end{align*} 
-\] 
- 
-<callout type="danger" icon="true"> 
-Never connect a normal diode or LED directly to an ideal voltage source in forward direction.  \\ 
-The diode current must be limited. \\ 
-The used resistor is often called **shunt resistor**. 
-</callout> 
- 
-==== Special Diodes ==== 
-=== Z-Diodes === 
- 
-If the reverse voltage of a diode becomes too large, the diode enters **breakdown**.   
-In this region, the reverse current rises strongly. 
- 
-Two physical effects can cause breakdown: 
- 
-  * **avalanche breakdown:** charge carriers gain enough energy to free additional charge carriers by collisions. 
-  * **Zener breakdown:** in strongly doped pn junctions, charge carriers can cross the barrier by a quantum-mechanical effect. 
- 
-For ordinary diodes, breakdown is usually unwanted and can destroy the diode if the current is not limited.  \\ 
-**Z-diodes** are designed to operate safely in this reverse-breakdown region at a defined voltage \(U_{\rm Z}\). 
- 
-The current must still be limited by the surrounding circuit. \\ 
-In its operating range, the diode voltage is approximately constant: 
- 
-\[ 
-\begin{align*} 
-u_{\rm Z}\approx U_{\rm Z}. 
-\end{align*} 
-\] 
- 
-The piecewise-linear model is 
- 
-\[ 
-\begin{align*} 
-u_{\rm Z} 
-\approx 
-U_{\rm Z}+r_{\rm Z} \cdot i_{\rm Z}. 
-\end{align*} 
-\] 
- 
-<panel type="info" title="Z-diode preview"> 
-  * Z-diodes are useful for voltage limitation and voltage stabilization.   
-  * Z-diodes are still conventional diodes in the forward direction.  
-</panel> 
- 
-<WRAP> 
-{{url>https://www.falstad.com/circuit/circuitjs.html?running=false&ctz=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-ccUi7ZCAAKocpCZFLTcgoLqiIMJmQQKAKe0CehEEBB6AAGggADUOQQ6NzFAR1BA1LGAD6eyjqJBQCiJbl0UsV6u23n0Gkl4h5iADtsczJ9ihiL1JGfxeNzxcdIR1PPdkuxgBan2OdfGJ-AECmwJhDWWHGa5-JIEf3QY1gAZjoAK5hVgAL2YfxmE0CpnwGapRHPOpb0keJEhfNIoJqOsCDAagkAwpFwSTaChBZRkyiZVl8kVaZcG6LY+DSaD9juXUXjOC5cCNJALXwwZoAIXBLWeN4Ph4bs+R2AhqDES8FRkXBoCgPFEIoyhfXoIQD1YcwrGYDkEkSODtTwWRA1jEMQFQ9QMGmPhRAzfc12zXT1FQ7UnQUAy13LKtNMgMc0gpPtsGstJ2xzPElKgZsu1XNJbObdpyBAKgYp7Q8OWndRcEUad2mbfyQECsRcAyOQ0G5MRa2s1oQEARMI504ktPKyAVys2cqqttMBZmYktpzylzmo7aYLgYJBqVqlBBRAd8LE0ewdE0ExjG0CJLH8OdkztIR6n68cxo8XQfD8QIjAWpa5wwAVRPINRwLG7QgmAowbEO5hFosZagA noborder}}  
-</WRAP> 
- 
-=== LEDs === 
- 
-An LED is a diode that emits light in forward direction. The required forward voltage depends on the semiconductor material and therefore on the color. 
- 
-<tabcaption tab_led_forward_voltage|Typical LED forward voltages> 
- 
-^ LED color ^ Typical \(U_{\rm TO}\) ^ 
-| infrared | \(\approx 1.3~{\rm V}\) | 
-| red | \(\approx 1.6~{\rm V}\) | 
-| yellow | \(\approx 1.7~{\rm V}\) | 
-| green | \(\approx 1.8~{\rm V}\) | 
-| blue | \(\approx 3.2~{\rm V}\) | 
- 
-<callout type="warning" icon="true"> 
-LEDs usually tolerate only small reverse voltages.   
-Do not operate an LED in reverse direction unless the datasheet explicitly allows it. 
-</callout> 
- 
-~~PAGEBREAK~~ ~~CLEARFIX~~ 
  
 ===== Exercises ===== ===== Exercises =====
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 \[ \[
 \begin{align*} \begin{align*}
-U_{\rm E}=5.0~{\rm V},+U_{\rm I}=5.0~{\rm V},
 \qquad \qquad
 R=1.0~{\rm k}\Omega. R=1.0~{\rm k}\Omega.
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 U_R U_R
 = =
-U_{\rm E}-U_{\rm D}+U_{\rm I}-U_{\rm D}
 = =
 5.0~{\rm V}-0.7~{\rm V} 5.0~{\rm V}-0.7~{\rm V}
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 \[ \[
 \begin{align*} \begin{align*}
-U_{\rm E}=12~{\rm V},+U_{\rm I}=12~{\rm V},
 \qquad \qquad
 R=560~\Omega. R=560~\Omega.
Line 831: Line 719:
 \[ \[
 \begin{align*} \begin{align*}
-U_{\rm E}+U_{\rm I}
 = =
 RI_{\rm D} RI_{\rm D}
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 \[ \[
 \begin{align*} \begin{align*}
-U_{\rm E}+U_{\rm I}
 = =
 RI_{\rm D} RI_{\rm D}
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 I_{\rm D} I_{\rm D}
 = =
-\frac{U_{\rm E}-U_{\rm TO}}{R+r_{\rm F}}.+\frac{U_{\rm I}-U_{\rm TO}}{R+r_{\rm F}}.
 \end{align*} \end{align*}
 \] \]
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 ===== Embedded resources ===== ===== Embedded resources =====
- 
-<WRAP group> 
-<WRAP column half> 
-<panel type="info" title="PhET: Semiconductors"> 
-Use this simulation to explore doping and the formation of a diode. 
- 
-{{url>https://phet.colorado.edu/en/simulations/semiconductor 700,500 noborder}} 
-</panel> 
-</WRAP> 
- 
-<WRAP column half> 
-<panel type="info" title="Falstad: Diode I/V curve"> 
-Use this simulation to compare a resistor characteristic with the nonlinear diode characteristic. 
- 
-{{url>https://www.falstad.com/circuit/e-diodecurve.html 700,500 noborder}} 
-</panel> 
-</WRAP> 
-</WRAP> 
  
 ~~PAGEBREAK~~ ~~CLEARFIX~~ ~~PAGEBREAK~~ ~~CLEARFIX~~