circuit_cook
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Hi, all:
I designed a bandgap, which is the Kunjit type circuit. I have doubt about the startup. I know there is positive and negative feedback in the bandgap. And at start up, I need to gurantee that negative feedback is larger than the postive feedback, so the overall is negative feedback, but I don't know how in this case. I ran two power supply ramping up simulations with a ramping time of 10u and 1s, the output is attached. va is the node of negative feedback, and vb is the node of positive feedback. The waveform shows sometimes the vb is larger than va, but it doesn't show any oscillation, the circuit seems to start up fine. Does the simulation shows the real scenario, or could there be problems, how can I gurantee the corret startup. The startup circuit is an inverter type that compares a reference current to generated IPTAT, and pulls the PMOS. Also the OTA biasing is a current mirror to MP1, so self biased, does this make it harder to startup?
Thanks. Judy
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