Biasing with a diode?

[raulgrell]

Hey
Would there be any advantage to bias a transistor (BJT/JFET/MOSFET) using a diode? I figure the result of doing so would set a given voltage supply to the transistor, but one could control the amount of current that reaches it... What would the effects of that be (if any)?

Are there any circuits that employ this technique already?
Input?

Cheers

[R.G.]

All biasing methods establish a more-or-less constant voltage from which you derive the stable working operation of the circuit. Mostly this is done with resistors, but using a diode, LED, zener, etc. may offer some advantage in that the diode voltage is more fixed over a wider range of currents than a resistor string. There are situations where this is an advantage, but there's no good across-the-board generalization to be made about it, other than what I just did.