Page 1 of 1

Unipolar (0-2V) Fast ADC Operation

Posted: Wed Mar 30, 2022 1:56 am
by rjw
Hi All,
There's some documentation available for the fast DAC describing how voltage bias is added to the fast DAC output to shift its level from unipolar 0-2V to the standard -1 to +1V range. By removing some resistors you can remove this and turn the DAC in to a unipolar, 0-2V output (https://ln1985blog.wordpress.com/2016/0 ... rformance/)
Is there any equivalent modification possible for the fast ADCs that would change the LV range to 0-2V? I have been looking for information on the "Amplifier & filter" frontend block for the ADC, but I guess this falls in the secret sauce portion of the hardware schematics. Additionally the reference designs in the ADC datasheet (LTC2145-14) are all for AC coupled signals.
Any thoughts on this would be greatly appreciated!

Re: Unipolar (0-2V) Fast ADC Operation

Posted: Thu Jun 02, 2022 8:29 am
by redpitaya
Unfortunately we do not have an example of that, however, a most simple way would be to change the input range from +-1 to +-2V would be by changing the values of input stage divider resistors or adding -1V offset to the signal with some external circuit.