You may use three internal OpAmps of the PSoC4 with external resistors to adjust the gain. Do not use a too high gain, the specs for cmrr and offset are not the best, Take care that under all circumstances the inputs are in the range 0V to VDDA
My inputs is differential (+/- ) not single ended so need connect different voltages.
May be pavloven can help with example schematic ?
Perhaps you only need to provide the offset signal as an example
You can pick up the offset and gain for the scheme on the attached picture (AC only)
I have similar requirement. Pavlolen, can you please explain the circuit you have posted for offset. Thanks in advance!!!
This is a classic instrumentation amplifier.
The only problem is that it has unipolar power.
Therefore, a small positive bias must be present at the inputs + of the operational amplifiers.
A variable 47 kΩ resistor aligns this offset to provide maximum common-mode rejection.
Thanks Pavlov.. I understand there has to be same offset for both the inputs. Right?? Can we apply this offset with internal reference voltage available with psoc?? Is it necessary to find right offset with variable resistance 47K. Also what the arrow near 47k indicates?? Does it have any relation with ground?? Sorry for putting so many questions.. thanks for your support!!!
Yes, the bias voltage for both inputs can be any in a wide range (about 0.5 to 3 volts).
The main thing is that the bias + signal is within the operating range. (No signal limit at the output)
You can use the internal / Vref PSoC, but always with the repeater on OPamp. I prefer the IDAC + resistor.
A simple way to properly set the potentiometer:
Connect both amplifier inputs together (InR and INL) and apply a sine (50-500 Hz, 0.5-2V)
Set the potentiometer to a position where the amplitude at the amplifier output is minimal.
(common-mode rejection = max)