TINA/Spice/OPA209: OPA209

See below and attached file for recommended circuit.  If you do not have a mid-supply reference voltage available I can recommend an op amp buffer circuit that can generate it.

TLV7031.TSC

Dear Tim, thank you for your answer and the circuit. Actually I prefer not to use any reference voltage as far as possible.  I wonder that if there is possible way to remove offset from the circuit I added and work properly. And could you tell me the reason of offset? 

There is -40mV offset from the source (VG1). When I simulate the circuit with offset ( adding dc source valued 40mV), I cant get the proper results. Could you advise another solution to handle with offset and get square wave at output  ?

There is a gaussmeter system. It generates sine wave signal. There is a -40mV offset of output of gaussmeter A1 and A2 signal. The signal is 10mV and 0.2Hz AC signal. My aim is to turn the sine wave signal to square wave signal. But offset of output of gaussmeter cannot allow to generate square wave by using comparator or zero cross detector. I try to build schmitt trigger circuit but result is same. How can I remove offset to get square wave ? COuld you offer a circuit to achieve that and remove offset ?

Hi Yildirim,

if the offset voltage is constant then this circuit could do what you want:

Kai

Hi Yildirim,

here's the file:

yildirim.TSC

I have put the -40mV offset already into the voltage source.

Kai

Thank you for your solution. Could you suggest any TI IC to achieve that for quick solution ? or any alternative? Because I cannot find  LMP7701 in local area.

Hi Yildirim,

in order to achieve a symmetrical output signal I have taken a OPAmp with a low offset voltage. And in order to achieve a full output swing I have taken a OPAmp with output rail to rail ability.

For experimenting you can use the TLC277 or even TLC272. To achieve symmetrical output signal the TLC272 should be selected for minimum offset voltage. Or you can adjust the -40mV reference voltage.

By the way, you can shift the output signal to any desired logic level by the use of a simple transistor inverting stage.

Kai