We use AD9245 to sample the signal detect single end amplifier with output voltage from 0 to 2 volts. We connect this output to Vin+. My question is that should we connect the Vin- to ground or to a voltage reference of 1 volt. If we connect the Vin- to ground, the differential input of AD9245 will be from 0 to 2 volts. If we connect the Vin- to 1 volt reference, the differential input of AD9245 will be from -1 to 1 volt. Could you please tell us which solution is right or both are right?
If you run AD9245 at 1V internal reference by connecting SENSE pint to ground and bias VIN- with 1V VREF, you shouldn't need 1K ohm to ground on VIN- side. The source impedance on each inputs should be well matched in order to achieve the best possible performance.
Questions are : When you say " change target half", what does that mean? Does it mean to set VIN+=0.5V = 1/2 VIN- ?
How do you set the output common mode voltage on AMP output(=VIN+ of AD9245)?
The digital code "0" covers within +/- 1/2 LSB (61uV here) and offset error of AD9245 on datasheet is typically +/-0.3% and Max +/-1.2% FSR @ 1.0V internal reference. Offset error at Max 1.2% case is 2V_FS*1.2*0.01=24mV. So it doesn't explain 60mV fully here. Please let me know if there is any change without 1K ohm on VIN- side.