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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] He calls it "a theoretical rectification formula giving the maximum rectification", with a footnote referencing a paper by Carl Wagner , Physikalische Zeitschrift 32 , pp ...
The Shockley diode equation relates the diode current of a p-n junction diode to the diode voltage .This relationship is the diode I-V characteristic: = (), where is the saturation current or scale current of the diode (the magnitude of the current that flows for negative in excess of a few , typically 10 −12 A).
The Shockley ideal diode equation or the diode law (named after the bipolar junction transistor co-inventor William Bradford Shockley) models the exponential current–voltage (I–V) relationship of diodes in moderate forward or reverse bias. The article Shockley diode equation provides details.
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 transfer function of an ideal diode has been given at the top of this (non-linear) section. However, this formula is rarely used in network analysis, a piecewise approximation being used instead. It can be seen that the diode current rapidly diminishes to -I o as the voltage falls. This current, for most purposes, is so small it can be ignored.
An I–V curve which is a straight line through the origin with positive slope represents a linear or ohmic resistor, the most common type of resistance encountered in circuits. It obeys Ohm's law; the current is proportional to the applied voltage over a wide range. Its resistance, equal to the reciprocal of the slope of the line, is constant ...
By the Shockley diode equation, the current diverted through the diode is: = { []} [7] where I 0, reverse saturation current; n, diode ideality factor (1 for an ideal diode) q, elementary charge; k, Boltzmann constant
In low voltage converters (around 10 volts and less), the voltage drop of a diode (typically around 0.7 to 1 volt for a silicon diode at its rated current) has an adverse effect on efficiency. One classic solution replaces standard silicon diodes with Schottky diodes , which exhibit very low voltage drops (as low as 0.3 volts).