Could anyone simulate these circuits in LTSpice?

[atferrari]

Around a year ago I simulated several precision rectifiers in LTSpice and they seemed to have a reasonable output.

Lately I repeated the simulation and found that the output is not like in the past: minimums take, alternatively, values of +0.2V and -0.4V. Maximum always 1.5 V.

I went to the LTSpice group where I was told that my circuit worked "out of the box". But I am still having the mentioned Vout.

Could anyone simulate the three attached circuits and tell the outcome? I did with three consecutive updated versions of LTSpice, so I do not think the problem comes from there.

I am asking this, because from the eight different circuit tested, all have a similarly flawed Vout.

Thanks for any help here.

 

[MikeMl]

All three simulated. 1&2 pretty fast completion. Cursory look at the waveform at the output looks cycle-by-cycle like the output of a full wave rectifier. 3 took much longer to complete. Looks like it is a filtered version of the full-wave rectifier with a long time constant.

Attached is a zoomed in view of #1

 

[atferrari]

Vout, as you get it from the simulation, is it acceptable? I recall getting a beter one in past simulations.

I recall using a different opamp (but do not know which one). I wonder if it was from LT at all...

 

[MikeMl]

The 1077 is a micropower 250KHz GBW Low voltage opamp. It is way too slow to follow your 2.5KHz waveform. Your circuit is GIGO. You will need an OpAmp with a GBW of at least 3MHz.