Approximate analytical expression for the tersminal voltage in multi-exponential diode models

• Many real diodes need to be modeled by two or more ideal diodes in parallel.
• For this case, the voltage cannot be expressed rigorously as an explicit function of the current.
• We propose a simple approximate solution for the voltage as an explicit function of the current.
• This approximate solution is more computationally efficient than rigorous iterative solutions.
• This solution makes direct analytic differentiation and integration possible.

We propose a simple approximate solution for the terminal voltage as an explicit function of the terminal current for diodes which need to be modeled by two or more ideal diodes in parallel. As a result, this solution is better suited for repetitive simulation applications than conventional implicit equations because of its inherently higher computational efficiency. Its explicit nature also makes direct analytic differentiation and integration possible. The approximate solution’s applicability has been assessed by parameter extraction and subsequent playback using measured I–V characteristics of lateral thin-film SOI PIN diodes and also using synthetic I–V characteristics of a solar cell.

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