In electronic circuits, diodes, as a basic semiconductor device, play a key role in rectification, switching, voltage regulation, signal modulation and other functions with their unique unidirectional conductivity. Among them, the cathode-connected diode, also known as the voltage regulator diode, is a special type of diode, and its cathode plays a particularly unique and important role in the circuit. This article will explore in depth the role of the cathode of the cathode-connected diode, and analyze its working principle, application scenarios and advantages.

1. The structure and working principle of the cathode-connected diode
Compared with ordinary diodes, the biggest difference between the cathode-connected diode and the ordinary diode is that it has a special silicon wafer structure. Two P-N junctions on the silicon wafer are connected to form a special doping area. This structure enables the cathode-connected diode to conduct current under a specific reverse voltage and maintain a relatively stable voltage drop when it is turned on.

When the positive pole (anode) of the cathode-connected diode is connected to the low potential end of the power supply and the negative pole (cathode) is connected to the high potential end of the power supply, it is in a reverse biased state. Before the reverse voltage reaches the breakdown voltage, almost no current flows through the diode and it is in a cut-off state. However, when the reverse voltage exceeds the breakdown voltage, a breakdown effect occurs inside the diode, generating an inverted current, i.e., a negative current. At this time, the diode begins to play a voltage stabilizing role.

2. The role of the negative pole connected to the negative pole of the diode
The main role of the negative pole connected to the negative pole of the diode in the circuit is to adjust and control the voltage of the circuit to ensure that the circuit can maintain a stable output voltage when the load changes. Specifically, the negative pole of the negative pole connected to the diode, as the control terminal, undertakes the following important roles:

Voltage stabilization: In the reverse breakdown state, the reverse breakdown voltage of the negative pole connected to the diode is constant. By connecting a current limiting resistor in series, it can be ensured that the current after breakdown does not exceed the allowable value, thereby maintaining a stable breakdown state for a long time. This feature makes the negative pole connected to the diode an ideal voltage stabilizing element in the circuit.

Protection circuit: In the circuit, the negative pole connected to the diode can reduce circuit noise and electromagnetic interference, protect the circuit from voltage fluctuations and overvoltage shocks, and improve the reliability and stability of the circuit.

Signal stability: In the high-power signal amplification circuit, the use of the negative pole connected to the diode can ensure the stability of the signal, improve the accuracy of the signal, and avoid signal distortion caused by voltage fluctuations.

3. Application scenarios of cathode-connected diodes
Due to their unique voltage-stabilizing performance, cathode-connected diodes have been widely used in electronic circuits. The following are some typical application scenarios:

Power regulator: A voltage regulator with cathode-connected diodes as the core can keep the voltage in the circuit within a stable range and is suitable for various electronic devices that require stable voltage power supply.

Protection circuit: Adding cathode-connected diodes at the power input or key circuit nodes can effectively prevent voltage fluctuations and overvoltage shocks from damaging the circuit.