VFC circuit problem - LTSpice

[raf_prze]

I've got problem with this circuit:




I mean... will it work? I suppose that transistor should work as a switch, being polarized by the negative voltage of op-amp output. But in my simulation it is in cut-off the whole time.

Can you please check it out? I attached my LTSpice simulation.

You can see, that 0.1u capicator is being loaded to the negative value by diode and polystyrene capicator.

View attachment vfc.zip

 

[crutschow]

What exactly is the circuit supposed to do? What output do you expect to see?

The transistor does momentarily conduct for about 2µs when the output pulses low.

 

[raf_prze]

Maximum emiter current is only 1uA. And the emiter-base voltage is lower then 0.6V...
Try to remove the transistor and you won't notice the difference.

 

[crutschow]

Without know how the circuit is supposed to operate it's difficult to tell you what might be wrong.

It appears to be a rather convoluted circuit. Where did it come from?