If you put up the schematic maybe we could offer suggestions - hard to help otherwise.

I haven't seen that one before and it isn't immediately obvious that R1 won't keep it from starting up reliably unless you force the operating point quite a ways from the 0 state. Basically you have to get the diodes turned on so that the delta-Vbe is greater than the I*R1 drop or the circuit won't wind up....  The problem is that the R2s steal all the current from the diodes.

You might be able to make it work with a nodeset for the PMOS gates = 0V. It might also work if you inject a small current into node "A" to make sure it isn't in the 0 state and increase Av from 1e3 to 1e5. But I think you'll need to figure out a startup circuit before you'll be able to simulate -- assuming one exists.

RobG wrote on Oct 19^th, 2013, 9:40pm:


Hi RobG you were right the nodes to apply node set are: node A and the gate of the PMOS. That's all, That band gap circuit does not have the problem of the "I" drop in the parallel resistors of the diodes because they are big, more or less 1MOhm each.

Thank so much for your help. I'm attaching the result.

RobG wrote on Oct 21^st, 2013, 7:32am:


Yes It is, It was published by Gupta student of Phillip Allen

RobG wrote on Oct 21^st, 2013, 9:29am:



I will send you and email please check it