Difference between Normal and Ideal Silicon Diode
Normal Silicon Diode
A "normal" silicon diode typically refers to the behavior of a real diode, which deviates from ideal diode behavior. Here are some characteristics of a normal silicon diode:
-
Forward Voltage Drop : When a normal silicon diode is forward-biased (anode voltage is greater than cathode voltage), it exhibits a finite forward voltage drop, typically around 0.6 to 0.7 volts for silicon diodes. This means that a voltage of at least 0.6-0.7 volts is required to turn on the diode and allow current to flow in the forward direction.
-
Reverse Leakage Current: In the reverse-biased condition (cathode voltage is greater than anode voltage), normal silicon diodes still allow a small amount of current to flow in the reverse direction. This is called the reverse leakage current. The magnitude of this current depends on the diode's specifications.
-
Recovery Time: When transitioning from forward-biased to reverse-biased conditions, normal diodes exhibit a certain amount of delay, known as the reverse recovery time. During this time, the diode continues to conduct in the forward direction. Ideal diodes do not have this delay.
-
Temperature Dependence: The characteristics of normal silicon diodes can vary with temperature, affecting their voltage drop and other parameters.
Ideal Diode
An "ideal" diode is a theoretical concept used for simplifying circuit analysis. An ideal diode has the following characteristics:
-
Zero Forward Voltage Drop: An ideal diode has no voltage drop when forward-biased, meaning it allows current to flow with zero voltage applied.
-
Infinite Reverse Resistance: An ideal diode has infinite resistance in the reverse-biased condition, meaning no reverse current flows through it.
-
Zero Reverse Recovery Time: An ideal diode switches instantaneously from the conducting (forward-biased) state to the non-conducting (reverse-biased) state without any delay.
-
Temperature Independence: The characteristics of an ideal diode are not affected by temperature changes.
In practice, real diodes exhibit behavior that deviates from these ideal characteristics, and the extent of deviation varies among different types of diodes. However, the concept of an ideal diode is useful for simplifying circuit analysis and understanding the basic behavior of diodes.
For specific applications, such as rectification (converting AC to DC), power regulation, or signal clipping, engineers select real diodes based on their specifications and characteristics. These diodes are considered "normal" silicon diodes.