I was wondering if there exist any relatively simple circuit which would have an I-V characteristic similar to that of a diode (i.e. exponential but small before the cut-in voltage) but with a higher cut-in voltage. I know I could just have several diodes in series but this quickly becomes impractical as I need the cut-in of around 5V which means around 8 diodes in series.
EDIT: Actually, what is important for me is that diode to have a smoother knee in the I-V characteristic. The more evidently exponential the thing the better.
How important is the exponential part of the I-V? As @nidhin suggested, 2 LED's in series could work. or a 5V zener.. or a 2 2.5V zeners in series.
The low voltage zeners are somewhat exponential, but not as good as diodes.
OK then try 2 LED's.