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How to do the noise analysis about Bandgap circuit?

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holddreams

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bandgap noise

How to do the noise analysis about Bandgap circuit?
Only measure the PSRR?
Thanks.
 

paulux

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bandgap noise analysis

For PSRR, just add ac signal on top of DC supply voltage.
For noise simulation, use .noise in Hspice simulation.
 

montage2000

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bandgap noise simulation

simulation is easy but abalysis is complex
 

edajason

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noise bandgap

I think you should also give a ac source when performing the noise analysis, where?

paulux said:
For PSRR, just add ac signal on top of DC supply voltage.
For noise simulation, use .noise in Hspice simulation.
 

jcpu

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eldo noise simulation of bandgap

BGR with OPamp looks like closed loop system,
as shown in attachment "BGR_sch.jpg".
I was also wondering about its noise performance,
and posted relevant topic.

Some answer was :
Break the loop, insert noise source, and do .noise simulation

which I did not quite understand it's relation to my original purpose:
Evaluate closed loop BGR noise performance
 

sina25

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ldo band gap noise analysis

jcpu, if the temperature changes, the difference between V+ and V- change?, and why?

thanks
 

montage2000

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noise and bandgap

use small signal snalysisy
 

orley

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bandgap noise

if your bandgap include OPA,you must insert noise source in the loop of the bandgap system;but your bandgap only used transistors , you may refer to analysis of noise in transistor at chp.7 of design of analog CMOS integrated circuits by Razavi.

Regards!
 

jcpu

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noise analysis for bandgap reference

sina25 said
jcpu, if the temperature changes, the difference between V+ and V- change?, and why?

If case of schematic attached by me, voltage between v- and v+ could be different by <40mV for comercial temperature range, and
YES the opamp gain (20+dB) does looks too low to me.
Silicon results is 1.17V+/- 40mV for 50 samples, and temperture curvature to be measured.
I'll keep you posted for furthur temperature results.
 

edajason

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noise simulation bandgap

The simple way to get the noise volt in rms: put a ac source at the vcc, and do noise analysis, get output voltage noise spectral density, and take the rms value (from low freq to 100kHz should be enough). This way you can simply get the output noise in rms (in certain bandwidth).

orley said:
if your bandgap include OPA,you must insert noise source in the loop of the bandgap system;but your bandgap only used transistors , you may refer to analysis of noise in transistor at chp.7 of design of analog CMOS integrated circuits by Razavi.

Regards!
 

alok_ky

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output noise of bandgap

i think, adding sine/ square wave on hte top of dc supply voltage and finding PSRR should be sufficient.

Also, stability analysis is a must.
 

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