Semiconductor & Computer Engineering
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== Overview == | == Overview == | ||
| − | A diode is a two-[[terminal]] [[electronic device]] that allows [[current]] to flow in just one direction. When flowing in the | + | A diode is a two-[[terminal]] [[electronic device]] that allows [[current]] to flow in just one direction. When flowing in the ''forward-biased direction'', the diode acts as a [[wire]] with very low [[resistance]], creating a short-like condition. Attempting flow in the ''reverse-biased direction'' will result in a very high resistance, prohibiting the flow of current, creating an open circuit condition. |
| + | |||
| + | == Ideal Diode == | ||
| + | The [[current-voltage characteristic]] of an '''[[ideal device|ideal]] diode''' is shown below. | ||
| + | |||
| + | :[[File:ideal diode i-v.svg|400px]] | ||
| + | |||
| + | The forward resistance (<math>R_f</math>) of the ideal diode can be obtained through [[Ohm's law]] where the forward voltage (<math>V_f</math>) across the diode is 0 (given from the I-V curve above) and the forward current (<math>I_f</math>) is any amount of current. | ||
| + | |||
| + | |||
| + | :<math>R_f = \frac{V_f}{I_f} = \frac{0 \text{V}}{\text{Any positive current (e.g., 5 mA)}} = 0 \Omega</math> | ||
| + | |||
| + | |||
| + | When conducting, an ideal diode acts as a wire with 0 Ω of [[resistance]]. In other words, in the forward-biased direction, an ideal diode is a [[short circuit]]. | ||
| + | |||
| + | :[[File:ideal diode forward biased.svg|300px]] | ||
| + | |||
| + | For the reverse-biased resistance (<math>R_f</math>), the reverse voltage (<math>V_r</math>) across the diode is any negative value and the reverse current (<math>I_r</math>) is 0. | ||
| + | |||
| + | |||
| + | :<math>R_r = \frac{V_r}{I_r} = \frac{\text{Any negative voltage (e.g., -1.5 V)}}{0 \text{mA}} = \infty \Omega</math> | ||
| + | |||
| + | When resisting, an ideal diode acts as a wire with ∞ Ω of [[resistance]]. In other words, in the reverse-biased direction, an ideal diode is an [[open circuit]]. | ||
| + | |||
| + | :[[File:ideal diode reverse biased.svg|300px]] | ||
| + | |||
| + | The above can be expressed as a step function. | ||
| + | |||
| + | :<math> | ||
| + | I_D = | ||
| + | \begin{cases} | ||
| + | 0, & V_D\leq 0 \\ | ||
| + | \infty, & V_D> 0 | ||
| + | \end{cases} | ||
| + | </math> | ||
| + | |||
{{stub}} | {{stub}} | ||
[[Category:electronic components]] | [[Category:electronic components]] | ||
Latest revision as of 01:39, 6 August 2018
A diode is a two-terminal electronic device that permits the flow of current primarily in one direction.
Overview[edit]
A diode is a two-terminal electronic device that allows current to flow in just one direction. When flowing in the forward-biased direction, the diode acts as a wire with very low resistance, creating a short-like condition. Attempting flow in the reverse-biased direction will result in a very high resistance, prohibiting the flow of current, creating an open circuit condition.
Ideal Diode[edit]
The current-voltage characteristic of an ideal diode is shown below.
The forward resistance () of the ideal diode can be obtained through Ohm's law where the forward voltage () across the diode is 0 (given from the I-V curve above) and the forward current () is any amount of current.
When conducting, an ideal diode acts as a wire with 0 Ω of resistance. In other words, in the forward-biased direction, an ideal diode is a short circuit.
For the reverse-biased resistance (), the reverse voltage () across the diode is any negative value and the reverse current () is 0.
When resisting, an ideal diode acts as a wire with ∞ Ω of resistance. In other words, in the reverse-biased direction, an ideal diode is an open circuit.
The above can be expressed as a step function.
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