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Old 26th August 2006, 07:06 AM   #1
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Question LM3875 at low gain

Has anybody tried using one of these chips at low or even unity gain? Are they stable? Any thoughts or advice?

I would like to use a SRPP preamp/driver stage but the gain will be too high normally, but at low gain it should work very well -- if the chip is stable.

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Old 26th August 2006, 08:22 AM   #2
Nuuk is offline Nuuk  United Kingdom
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No they are not stable at low gain. If you want a low gain GC, use something like the OPA541/549.
The truth need not be veiled, for it veils itself from the eyes of the ignorant.
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Old 26th August 2006, 09:40 AM   #3
ash_dac is offline ash_dac  United Kingdom
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In the LM3875 datasheet figure 2 they show additional compensation capacitance to reduce HF ac gain. I assume the LM3875 is compensated for gains greater than 10.

Can the LM3875 be compensated for lower gains ?

I was thinking about a LM3875 regulated-LM3875 amplifier...

edit:- never realised how sensitive these chips are...picking up fluorescent noise!
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