I am trying to figure out a simple application/ circuit that would allow me to shift the voltage a little bit. Lets say we have an input voltage of range from 0 to 1 V. I need an output voltage of 0.2 to 1.2 V. This is just an example but I am looking for a generic solution. There is no negative voltage available in the circuit.
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\$\begingroup\$ @le_top: No, that won't work at all. Draw it out on paper and maybe you'll see why. \$\endgroup\$ – Dave Tweed Oct 12 '19 at 20:01
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\$\begingroup\$ Ok, maybe I wrote it out wrong - so I'll delete my comment as your drawing is what I meant to describe. \$\endgroup\$ – le_top Oct 12 '19 at 21:02
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The classic 4-resistor difference amplifier will do what you want:
simulate this circuit – Schematic created using CircuitLab
This circuit keeps the difference between Vout and Vref equal to the difference between V+ and V-, effectively adding Vref to V+ if V- is grounded.
The opamp tries to keep its two input terminals at the same potential using negative feedback:
$$ \frac{V_{out} + V_-}{2} = \frac{V_{ref} + V_+}{2}$$
Multiply both sides by 2 and rearrange the terms to get:
$$V_{out} - V_{ref} = V_+ - V_-$$
answered Oct 12 '19 at 20:11
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\$\begingroup\$ Yes, I messed up the terminals. I think its the simplest way, thanks. \$\endgroup\$ – Łukasz Przeniosło Oct 12 '19 at 20:24
