Hi all,
I'm simulating a DC log amplifier (as in AofE p212 fig 4.35) with LT spice, and noticed a few problems.
Firstly my application runs off a 9V battery and therefore requires micro power op amps. I intend to use 9V and 0V for the supply rails of the op amps, and apply a virtual earth point of 0.6V to the base of the transistor, and non-inverting input of op amp. R2 of the non- inverting amplifier is also connected to this virtual earth.
Running through simulations with the micro power op amps I noticed the Chopper amplifiers LTC1047, LTC1049 allow simulation to converge within minutes (although when virtual earth is raised to 0.9V or above there is no convergence). The other op amps don't converge irrespective of virtual earth value? Is this an issue because:
1) I have effectively 2 ground points
2) The type of op amp used
3) LT spice simulator
Is there any features within LT spice that reduce accuracy but improve simulation time? Hope to hear from you soon,
Cheers,
ozzy