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Old 6th December 2007, 10:07 PM   #1
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Default LED bias and differential pairs

Have been considering using an LED to bias my Raven linestage. Normally, I see either a common cathode resistor to bias the diff pair, or a CCS. Would an LED be just as good an option?

I will require a 2V, 40 mA bias node, so I was planning on paralleling two red LED's. Yes, no ?

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Old 6th December 2007, 10:20 PM   #2
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An LED is exactly the opposite of what you need. It's an excellent voltage source (i.e., low source impedance) whereas what you need for a diff amp is an excellent current source/sink (i.e., high source Z).
And while they may not be as strong as apes, don't lock eyes with 'em, don't do it. Puts 'em on edge. They might go into berzerker mode; come at you like a whirling dervish, all fists and elbows.
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Old 6th December 2007, 11:06 PM   #3
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Suspected such. We shall stick with the resistor for now.
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