Tool/software:
Hi,
I have uni-polar signal (0-2V) inserted to FDA (INP) to drive the ADS4122.
The ADC have Differential input voltage of 2 Vpp and VCM of 0.95V.
from the data sheet:
The analog input consists of a switched-capacitor-based, differential, sample-and-hold architecture. This
differential topology results in very good ac performance even for high input frequencies at high sampling rates.
The INP and INM pins must be externally biased around a common-mode voltage of 0.95 V, available on the
VCM pin. For a full-scale differential input, each input INP and INM pin must swing symmetrically between (VCM
+ 0.5 V) and (VCM – 0.5 V), resulting in a 2-VPP differential input swing.
My question is:
what constant value I need to insert to INN input of the FDA?
is this value is the 1V which is half of the input voltage ?
in the application guide from TI I see, the VCM have the value of half of the input voltage so it's also inserted to the INN. This is no this case!!
pls. advise
regards
Zeev Gerber
