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- Biasing of LM3900 op amp
September 16, 2009, 10:53 am
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I have a supply of LM3900 single supply quad op-amps and want to use one as
a 3 stage audio band pass filter.
I can not seem to sort out the biasing of the +ve input.
Some application notes show it tied to the positive rail via a 1M to 10M
resistor and other application notes 75 k ohms. Wide variation here!
Can someone please give me some guidance on this?
From what I can gather the usual way of biasing the +ve input to half rail
does not apply to this device.
- petrus bitbyter
September 16, 2009, 11:59 am
Re: Biasing of LM3900 op amp
Have you looked at the data sheet yet? ... plenty of description and
Quoting: 'Operation of this amplifier can be best understood by noticing
that input currents are differenced at the inverting-input terminal and this
difference current then flows through the external feedback resistor to
produce the output voltage'. etc. It's all there.