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Linear regulator operating point over input DC Sweep

Johanny Saenz

Hi all.

I'm sweeping the linear regulator input voltage on DC from 0V to maximum expected Vin. However, as the OTA that makes part of LDO is internally supplied by the output voltage, the simulation will never turn on the OTA and it will find a very stable point of operation in 0V. it is like the dilemma of chicken and egg. 

How I could force to start the OTA and calculate the minimim input voltage?

Thanks

  • Andrew Beckett

    Probably you need to set an initial condition (in ADE using Simulation->Convergence Aids) to force a voltage onto a node in the circuit to allow it to start. Of course, you should ask yourself is this really a simulation artefact and will the actual circuit start in real life too?

    Regards,

    Andrew.

  • Johanny Saenz

    When I run a DC sweep from higher to lower values, the simulation converge to the desired value in a certain interval. However, there is a remaining and non desirable stable point at the beginning of the sweep (upper values),which can be easily tackled using a nodeset statement set to the regulator output voltage.

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