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Old 11th August 2006, 06:09 PM   #1
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Question Have to calculate gain for typical small JFET preamplifier

I would like to made small and simple JFET preamplifier with 6 dB gain.

I found simple circuit like this below, but I can not find out how to recalcultate required gain. Source resistor is key to go, but ...

If anybody here got some experience with JFETs please help


Thanks
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Old 11th August 2006, 07:31 PM   #2
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Vg=R(1)/{R(2)+1/Gm} or R(1)/R(2) approximately
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Old 11th August 2006, 09:53 PM   #3
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Thanks

Is Gm transductance?
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Old 11th August 2006, 09:59 PM   #4
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yes
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Old 11th August 2006, 11:22 PM   #5
Tim__x is offline Tim__x  Canada
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It should noted that Gm is very inconsistent from batch to batch, so if you need precise gain it'll need trimming.
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