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Beide Seiten der vorigen Revision Vorhergehende Überarbeitung Nächste Überarbeitung | Vorhergehende Überarbeitung | ||
circuit_design:2_diodes [2023/11/26 20:00] – mexleadmin | circuit_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. | + | 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. |
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, | 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, | ||
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===== 2.3 Special diodes ===== | ===== 2.3 Special diodes ===== | ||
- | So far the silicon PN diode and the Z-diode | + | So far the silicon PN diode and the Z-diode |
- | ==== 2.3.1 Diodes for Electic | + | ==== 2.3.1 Diodes for Electric |
==== Germanium diode ==== | ==== Germanium diode ==== | ||
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<panel type=" | <panel type=" | ||
- | 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 $R2$. | ||
- | {{url> | + | {{url> |
</ | </ | ||
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====== Study Questions ====== | ====== Study Questions ====== | ||
=== For self-study === | === For self-study === | ||
- | * On a U-I diagram, draw the characteristic | + | * On a U-I diagram, draw the characteristics |
* 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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< | < | ||
P-doping produces quasi-free electrons| | P-doping produces quasi-free electrons| | ||
- | Conductivity in semiconductors happens via conduction band 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 |