How Does Switching Diode Working

When a semiconductor diode is turned on, it is equivalent to a switch being closed (the circuit being turned on), and when it is turned off, it is equivalent to a switch being turned on (the circuit being turned off). Therefore, the diode can be used as a switch, and the commonly used model is 1N4148.". Due to the unidirectional conductivity of semiconductor diodes, the PN junction is conductive at a positive bias voltage, and the resistance in the conductive state is very small, ranging from tens to hundreds of ohms; Under reverse bias voltage, it is in a cut-off state, with a high resistance. Generally, the silicon diode is at 10 Μ Above Ω, germanium tubes can also range from tens to hundreds of kiloohms. Using this characteristic, the diode will play a role in controlling the current on or off in the circuit, making it an ideal electronic switch.

The above description is actually applicable to any ordinary diode, or the principle of the diode itself. However, for switching diodes, the most important feature is their performance at high frequencies.

At high frequencies, the barrier capacitance of the diode exhibits extremely low impedance and is connected in parallel with the diode. When the capacitance of the barrier capacitor itself reaches a certain level, it will seriously affect the switching performance of the diode. Under extreme conditions, the diode will be short-circuited, and high-frequency current will no longer pass through the diode, but directly bypass the potential barrier capacitor, causing the diode to fail. The barrier capacitance of switching diodes is generally very small, which is equivalent to blocking the path of barrier capacitance, achieving the effect of maintaining good unidirectional conductivity under high-frequency conditions.