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Winfield Hill wrote:
No, it means its a better diode at low currents. See my curves again, http://www.picovolt.com/win/elec/com...de-curves.html Note the 1n458 and the JFET diodes, which follow the theoretical 60mV/decade rule down to very low currents. As for Roy Lewallen's "ratio of reverse to forward current" argument, there is no reverse current for these fine fellows, at least for DC and reasonably low frequencies. Sure there is. All diodes have reverse current. It's the very crummy gold-doped 1n4148 that falls over. Awwkk! The gold doping is done to dramatically reduce charge storage time. Without it, the voltage across a diode continues to be in the forward direction for some time after you reverse the current through it. While a non-gold-doped diode might look good in DC tests, it makes a lousy rectifier of RF. In the extreme case, it acts like a PIN diode (which is simply a diode designed intentionally to have a long charge storage, or reverse recovery, time). Alas, life is full of tradeoffs. Roy Lewallen, W7EL |