# A question on factors affecting the offset removal of an opamp circuit

I will use a function generator module which outputs 0-1V sine-wave for frequencies of interest from 0.5Hz to 30kHz importance. So my input will be 0-1V sine wave but I want to obtain an AC sine wave with 1V amplitude and 0V offset i.e symmetric swing. I also want to achieve this not by using too complicated circuitry.

Theoretically below circuit works to eliminate such offset:

And here is the output 1V with symmetric swing:

I don't have experience with these but I have couple of questions:

1-) What component in practice should replace Voff for a better accuracy? Voff can be a voltage divider or a reference voltage; but what in practice is better for a reliable offset removal?

2-) The circuit above assumes that the incoming sine is always a 1Vpp with 0.5V offset. What if the Vin's offset varies, is there a solution for that? I mean is there a zero offset Vout solution for a possible varying offset of Vin?

I don't know what is the main issue in such circuits so these are the questions I need to figure out. Maybe some other things like power supply stability, opamp type ect. more important. It would be great to hear if some could share experience.

• The simplest "DC-offset removal" is a capacitor. Try 3.3µF capacitor and 1Meg resistor (high-pass filter) at the input of a voltage follower. Or use a voltage divider instead Voff. Connect the voltage divider between Vcc and Vee R1 = 2.2k and R2 = 3.3k
– G36
Commented Nov 13, 2018 at 17:19
• Are you sure the cap will work down to 0.1Hz input? Commented Nov 13, 2018 at 17:46
• You say 0.5Hz in your question. For 0.1Hz you need a bigger cap
– G36
Commented Nov 13, 2018 at 17:48
• Im not sure the cap will work well for such low freq. Commented Nov 13, 2018 at 17:50
• AC coupling doesnt pass DC and I might need down to 0.5Hz or even lower freq like 0.1Hz accurate way Commented Nov 13, 2018 at 17:51