NNTP-Posting-Date: Mon, 13 Jan 2003 07:14:36 -0600
From: "john walton"
Subject: Re: How do you amplify DC voltage?
Date: Mon, 13 Jan 2003 08:13:01 -0500
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I use a chopper amp from TI in a pH meter. A good source to check is Analog
Devices or Texas Instruments (which now owns Burr-Brown.) In particular,
ADI has an application note on "finding the needle in a haystack".
Other things to consider -- at small, very small voltages, every node
potentially picks up radio frequency interference, computer noise etc -- you
want top and bottom ground planes, decoupling of the power supply, isolation
of digital and analog grounds etc. -- again see the apnotes at TI on ADC
selection since the info there will speed your quest.
"Jason Hsu" wrote in message
> What do you use to amplify small DC voltages?
> The trouble with amplifying DC voltage is the interference from DC
> offsets in the amplifier. While you can use a high-pass filter to
> remove the DC offset for an amplifier in the audio or higher
> frequencies, this is not an option for DC, as this would attenuate the
> DC signal as much as the DC offset.
> Jason Hsu, AG4DG