Vcm is for both inputs. It pushes the signal from both sides.
Speaking regardless of the input/output demans of picture I shared; Is this what I should understood ?
We have an input signal Vi(t)=2.cos(wt)
Vcm set to 2V and Vcc=5V, gain set to 1
Output is now Vo(t)=Vi(t)+2
Signal should swing between 0-4V but since Vcm is for both inputs, output positive alternance clips/saturated at 3V (Vcc-Vcm)
To be able to get rid of negative alternance clipping I need to increase Vcm but now positive alternance may get clipped.
The solution is increasing the voltage divider (decreasing input for inamp) so I will not be affected by positive alternance clipping. Because my peak will be way under it. Putting a gain solves the decreased input.
I'll add that I don't think this necessarily calls for an inst. amp. Inst amps are good if high input impedance or economical matched resistors are needed. But you benefit from neither in this case. See the below where that could be any decent dual opamp:
LM741 dual supplied +-20Vdc output can be +-16V at tops. Slew rate is 0.7V/uS
AD623 single supplied 5Vdc output can be 0.2 to (Vdc-0.15)V. Slew rate is 0.3V/uS
I've choosen AD623 because it is fast and (output swing/supply voltage) is good. I'm sincerely open to any opamp suggestions.
If you want good matched resistors search "ACAS" on digikey.
Because of the region I live buying from digikey costs me a month or more. Also limit for tax free shopping set to zero a few days ago and shipping cost is included.
Lets say I wanted to import 2$ product with 10$ shipping fee, total cost is 12$ and it's tax is 70% and it costs me 20$ (20% + 20% +20% 3 taxes added to each other).
I need to buy from local stores and they really don't have much options.
asdf44, FvM I really thank you both. And I'm in a need of shunt resistor current measurement methods.