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Forward Voltage Drop(VF) of a Diode
Aug 27, 2018

The most important feature of diodes is unilateral conductivity. In the circuit, the current flows from the positive pole of the diode to the negative pole. The following is a simple experiment to illustrate the forward and reverse characteristics of the diode. 1. forward characteristic. In an electronic circuit, the diode is connected to the positive electrode at the high potential and the negative electrode at the low potential, and the diode is turned on. This connection is called positive bias. It must be noted that when the forward voltage applied to both ends of the diode is very small, the diode still cannot be turned on, and the forward current flowing through the diode is very weak. Only when the forward voltage reaches a certain value (this value is called the threshold voltage), germanium tube is about 0.2V, silicon tube is about 0.6V), the diode can be directly on. After conduction, the voltage at both ends of the diode remains basically unchanged (germanium tube is about 0.3V, silicon tube is about 0.7V), which is called the forward voltage drop of the diode. 2. reverse characteristics. In an electronic circuit, the positive electrode of the diode is connected to the low potential end and the negative electrode is connected to the high potential end. At this time, almost no current flows through the diode. At this time, the diode is in a cut-off state. This connection is called reverse bias. When the diode is in reverse bias, there will still be a weak reverse current flowing through the diode, called leakage current. When the reverse voltage at both ends of the diode increases to a certain value, the reverse current will increase sharply, and the diode will lose its unilateral conductivity. This state is called diode breakdown.