11.1 : The Ideal Diode

A diode is a semiconductor device that allows current to flow in one direction only, making it a crucial component in electronic circuits for controlling the direction of current flow. An ideal diode is a simplified version of a real diode used to understand how diodes work in circuits. It possesses two terminals: the positive anode and the cathode, which is negative. When a positive voltage is applied to the anode relative to the cathode, the diode is in a forward-biased state, allowing current to flow through. In contrast, when the cathode is at a higher potential than the anode, the diode is reverse-biased. It inhibits current flow, functioning as an open switch.

The behavior of an ideal diode is depicted through piecewise linear I-V (current-voltage) characteristics, comprising two segments: a vertical line that illustrates current flow under forward bias and a horizontal line that signifies no current flow in the reverse-biased condition. This model showcases a sharp transition between conduction and non-conduction states, eliminating the gradual curve in real diodes.

While real diodes have some voltage drop when forward-biased and a tiny leakage current when reverse-biased, the ideal diode model ignores these aspects to simplify circuit analysis. This model is significant in rectifier circuits that convert AC into DC. During positive cycles of AC, the ideal diode conducts, making the output voltage equal to the input. In negative cycles, it blocks current, leading to zero output voltage. This process results in a DC output, essential for many electronic devices that require stable and continuous power.