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When more accuracy is desired in modelling the diode's turn-on characteristic, the model can be enhanced by doubling-up the standard PWL-model. This model uses two piecewise-linear diodes in parallel, as a way to model a single diode more accurately. PWL Diode model with 2 branches. The top branch has a lower forward-voltage and a higher ...
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.
In VHDL-AMS, a design consists at a minimum of an entity which describes the interface and an architecture which contains the actual implementation. In addition, most designs import library modules. Some designs also contain multiple architectures and configurations. A simple ideal diode in VHDL-AMS would look something like this:
A von Neumann architecture scheme. The von Neumann architecture—also known as the von Neumann model or Princeton architecture—is a computer architecture based on the First Draft of a Report on the EDVAC, [1] written by John von Neumann in 1945, describing designs discussed with John Mauchly and J. Presper Eckert at the University of Pennsylvania's Moore School of Electrical Engineering.
James Pomerene working on the IAS machine. The IAS machine was the first electronic computer built at the Institute for Advanced Study (IAS) in Princeton, New Jersey.It is sometimes called the von Neumann machine, since the paper describing its design was edited by John von Neumann, a mathematics professor at both Princeton University and IAS.
Figure 5: Small-signal circuit to determine output resistance of mirror; transistor Q 2 is replaced with its hybrid-pi model; a test current I X at the output generates a voltage V X, and the output resistance is R out = V X / I X. An idealized treatment of output resistance is given in the footnote.
The Shockley equation doesn't model this, but adding a resistance in series will. The reverse breakdown region (particularly of interest for Zener diodes) is not modeled by the Shockley equation. The Shockley equation doesn't model noise (such as Johnson–Nyquist noise from the internal resistance, or shot noise).
At high frequencies, the PIN diode appears as a resistor whose resistance is an inverse function of its forward current. Consequently, PIN diode can be used in some variable attenuator designs as amplitude modulators or output leveling circuits. PIN diodes might be used, for example, as the bridge and shunt resistors in a bridged-T attenuator.