As I am not very skilled with analog design I would like to get some pointers to what to look for/avoid common pitfalls.

I have a signal generator that outputs a sine wave. I want to center this sine wave at a specific voltage (V+/2). So the circuit I am designing is shown in the picture below.

What are the most important parameters to approach the ideal op. amp. in this case?

Other information that might be useful:

  • It is to be used on a battery-driven devices so low power consumption is positive.

  • Rail-to-Rail Input / Output.

  • 3.3V op. amp. preferred.


enter image description here

  • 1
    \$\begingroup\$ It doesn't need to be rail to rail input in an inverting configuration and you are aware that rail to rail outputs are never quite what they say they are. Output load is important too. \$\endgroup\$
    – Andy aka
    Commented Dec 1, 2013 at 19:55
  • \$\begingroup\$ @Andyaka: I was not aware of the inverting rail to rail fact so I will check that out (to learn why). In my case this output is connected to yet another op. amp. This will basically mean that the min/max output = power supply voltage? \$\endgroup\$ Commented Dec 1, 2013 at 20:03
  • 1
    \$\begingroup\$ Bandwidth is an important consideration and if you are feeding the above circuit into another op-amp why bother with the above circuit - it's unity gain so you are only adding noise by using this extra "do-nothing-much" stage. \$\endgroup\$
    – Andy aka
    Commented Dec 1, 2013 at 21:26

1 Answer 1


If you are looking for a specific OpAmp chip I'm sorry, I'm not familiar with any 3.5 V ones.

About other things, if it will be a battery driven device make sure the input impedance is high ( to consume less current ). Usually (extra) high input impedance OpAmps are doing worse with noise characteristics, but if that's not of terrible importance the trade off is good ( of course, you can also find OpAmps with many good characteristics, but it will be costly ). Also about noise, I assume this part of scheme will be a power stage, so I assume you will do some filtering at the output anyway. Also don't forget to check about the input bias currents, you want to keep them minimal - usually this comes at a cost of input current offset, but again, if precision is not at steak it is ok.

Oh and by the way, putting op-amp ( or the like ) tag would really help you get more potential good answers to your question ;)

  • \$\begingroup\$ Thank you for your inputs. This is actually not the power stage, but a small signal (50mV) sine wave. Adding the op amp tag ;) \$\endgroup\$ Commented Dec 5, 2013 at 12:13

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