Re: feeding ADC with too big input swing

On Jul 28, 1:17 am, Vladimir Vassilevsky <antispam_bo...@xxxxxxxxxxx>
wrote:
BW wrote:
What's your favorite trick of feeding a differential-input ADC with a
single-ended input (0-5V) that has twice the swing that the ADC
desires (0-2.5V differential, i.e. 1.25V +/- 0.625V for each input) ?

Resistor divider in half + op-amp buffer + single->differential op-
amp ? Is it possible with less components ?

It depends. AC or DC coupling, high or low frequency,
source/drive/referrence input impedance, how many channels, noise
requirements, etc.

For the low power low frequency, the minimum solution is something like
this:

http://www.abvolt.com/misc/single_diff.jpg

Hi, thanks for the reply!

Its definitely low-power (a monochrome video-signal), but the ADC
(LTC2202)
is sampling at 10 mhz and the signal is around half of that. One
channel,
DC-drive. Noise preferably in the ~100 uV range (I know this is larger
than
the 16-bit ADC LSB). My first idea was to simply use the LT1994 which
is in
one of Linears recommended input drives for the LTC2202, when
converting
a single-ended input. It's just that my input is 0-5V which requires
some
dampening.

Both would have the ground +
single-ended as inputs at some point anyway..

No. The whole thing can be fully differential.

I guess by separating the grounds of the single-ended input-device (a
sensor)
with the ADC-system you could have a differential input, if that is
what you
mean.

Best regards,
Bjorn W
.

Relevant Pages

  • Re: feeding ADC with too big input swing
    ... What's your favorite trick of feeding a differential-input ADC with a ... single-ended input that has twice the swing that the ADC ... AC or DC coupling, high or low frequency, source/drive/referrence input impedance, how many channels, noise requirements, etc. ...
    (sci.electronics.design)
  • feeding ADC with too big input swing
    ... What's your favorite trick of feeding a differential-input ADC with a ... single-ended input that has twice the swing that the ADC ... as opposed to grounding one of the ...
    (sci.electronics.design)