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convential Bandgap voltage ref. , need transient analysis?

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leonken

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When I simulate a convential bandgap voltage reference circuit by using Hspice, transient analysis is need or not? why? I already had a dc sweep analysis.
thank you.
 

Yes you need. To observe "the start-up condition of BG regulator", you'll have to do a transient simulation.
 

Re: convential Bandgap voltage ref. , need transient analysi

Does all convential bandgap voltage ref. have a start-up circuit?
 

most bias circuit need a start-up circuit
 

Re: convential Bandgap voltage ref. , need transient analysi

Below circuit is a banggap voltage reference.
If the current bias of the opamp derive from the gate terminal of M1 and M2, does it need a start up circuit?
 

Re: convential Bandgap voltage ref. , need transient analysi

this is a voltage reference circuit bu using peaking current source.
The author said:
In theory a start-up circuit is needed to prevent from the probably initial high voltage at the drain terminal of M2, but in practice such an initial condition is
highly unlikely in the circuit because of the ever existing leakage path.
I can not undersant the:such an initial condition is
highly unlikely in the circuit because of the ever existing leakage path.
where is the existing leakage path?
Does it dont need a start-up circuit?
 

Re: convential Bandgap voltage ref. , need transient analysi

BigBoss said:
Yes you need. To observe "the start-up condition of BG regulator", you'll have to do a transient simulation.
Click to expand...

How to do the transient simulation?
for example, to use a pwl vdd source to similate the start up period, the vdd start from 0v to 3.3V in 30ms and then check the waveforms of each nodes?
 

Re: convential Bandgap voltage ref. , need transient analysi

Ramping the vdd power for transient analysis is crucial for the start-up circuit.
Check the simulations for all the corner cases. Be aware of any parasitics you might
lost in the netlist for post-layout simulation..
 

Re: convential Bandgap voltage ref. , need transient analysi

Replace dc power with pulse power signal, then do transient simulation and plot the output wave. From the output wave,u can judge the stability of the circuit!
 

We need the transient analysis to check the start-up circuit and the final value.
 

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