how to do stability analysis for bandgap circuit?
Generally U shouldn’t check phase margin in bandgap (and other biasing circuits), because result of AC simulation may be deceiving. But always check stability during transient analisys with slow and fast supply voltage ramp. I cite http://www.edaboard.com/viewtopic.php?t=261515&highlight=ivanov+operational: ” Verification of the biasing circuit has to be done by transient simulation, with slow ramping of the supply voltage first, followed by switching of the load current and supply voltage. AC small-signal simulations may be deceiving. For example, it is interesting to notice that AC simulations of the phase margin in the voltage regulators provide results that would be unacceptable in the OpAmps (5o phase margin, for example). Yet, the simulations of step-response transient or experimental verification of this response on the silicon chip show quite sufficient excess stability. Also, the start-up problems in biasing circuits are likely to cause conditional instability, and AC simulati
