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The real diode now can be replaced with the combined ideal diode, voltage source and resistor and the circuit then is modelled using just linear elements. If the sloped-line segment is tangent to the real diode curve at the Q-point, this approximate circuit has the same small-signal circuit at the Q-point as the real diode.
Shockley derives an equation for the voltage across a p-n junction in a long article published in 1949. [2] Later he gives a corresponding equation for current as a function of voltage under additional assumptions, which is the equation we call the Shockley ideal diode equation. [3]
In certain real-world cases it is important to consider the losses that are incurred by this non-ideal diode effect. [35] However, when the slew rate of the current is not so severe (e.g. Line frequency) the effect can be safely ignored. For most applications, the effect is also negligible for Schottky diodes.
For simplicity, diodes may sometimes be assumed to have no voltage drop or resistance when forward-biased and infinite resistance when reverse-biased. But real diodes are better approximated by the Shockley diode equation, which has an more complicated exponential current–voltage relationship called the diode law.
The circuit is treated as a completely linear network of ideal diodes. Every time a diode switches from on to off or vice versa, the configuration of the linear network changes. Adding more detail to the approximation of equations increases the accuracy of the simulation, but also increases its running time.
The precision rectifier, sometimes called a super diode, is an operational amplifier (opamp) circuit configuration that behaves like an ideal diode and rectifier. [ 1 ] The op-amp-based precision rectifier should not be confused with the power MOSFET-based active rectification ideal diode.
Using these ideal diodes rather than standard diodes for solar electric panel bypass, reverse-battery protection, or bridge rectifiers reduces the amount of power dissipated in the diodes, improving efficiency and reducing the size of the circuit board and the weight of the heat sink required to deal with the power dissipation.
An ideal diode should have the following characteristics: When forward-biased, the voltage across the end terminals of the diode should be zero, no matter the current that flows through it (on-state). When reverse-biased, the leakage current should be zero, no matter the voltage (off-state).
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