how can i simulate the phase margin of this bandgap?

[newbie_1]

bandgap phase margin

how can i setup and do the ac simulation?

thanks

 

[sunking]

add large idea inductor in the loop(such as A and B), and add a small signal at it, then simulate the PM

 

[marshel]

simulate like this

 

[nuiscet]

why the small signal is added to the output of O.P.AMP ? not the input of it?

 

[zenisle]

first, create the open loop.
second, simulation phase margin

 

[suria3]

Hi,

In the loop, no matter which point u break to find the open loop gain, you will be getting the same gain and PM. The method shown to measure the PM is called the "Middlrbrook". The AC is actually given at the input of the gate (high input impedance) while the output is measured the the output of opamp (low output impedance)

Suria3.

 

[cliffj]

Try " stability" simulation in spectre.

 

[huojinsi]

To cliffj

How to simulate stability in spectre?

 

[bsrivastava]

I have tried for Inductor for stability analysis of Bandgap, but it didn't work for me.
We need to pick very large value of indictor (100 kilo henery) or so..
I am attaching the other testbench and hopefully it should work. For Phase Margin the difference of PM at point A to point B will be PM of bandgap.
The AC sources are out of phase to each other.

Any comments on the fundamentals is highly appreciated.

thanks

 

[arsenal]

hi bsrivastava,
your setup seems right,
btw, how can you setup to do the noise simulation of the bandgap? eg, i wanna simulate the equivalent output noise,
thx

 

[bsrivastava]

hi arsenal,
If I am getting your question correctly, is it PSRR?

If so I will connect AC noise source to Vcc, Vss separately and then 0.5 V AC to Vcc and Vss but out of phase so that the Vcc-Vss should be 1.0V AC.

Let me know if I answered your question.

thanx

 

[arsenal]

hi bsrivastava,
i just wanna simulate the equivalent output thermal and flicker noise,
thx