Bandgap design???????

[letan]

bandgap stability

I want to design a Bandgap, and how determine my bandgap is good? I must do what simulation. And if I want to simulate frequency response for my bandgap, I must compose my netlist? Please help me?
Thanks.

 

[rficdesigner]

bandgap design

Bandgap reference circuit: the function of this circuit is to generate a Reference Volatage or Current which is independent of PTV and supply.
Thus, what you need is to check whether Voltage or current reference is independent of of PTV and supply?

 

[letan]

design bandgap

Thanks for your reply. But if I need consider my bandgap's stability, what must i do?

 

[jecyhale]

bandgap stability analysis

Band gap can only generate a reference voltage independent PVT.

But if you want generate a reference current independent PVT, you need do more.

Three perfromance should be simulated with PVT

DC sweep with temperature for check the Vref
Tran for check the satblity and start up time.
AC for check PSRR.

 

[fmgay]

For bandgap or other references, you need do this:
1. do .op analysis to ensure the devices been properly biased.

2. do DC sweep to check output voltage vs. power, temperature. process.

3. do ac ayalysis to the the loop stable.

4. check psrr.

 

[svraj]

Another important bandgap analysis is to ramp-up the power supply for at least 1us in Transient analysis and check if the Bandgap settles to its desired value. You will have to include a start-up circuit for your bandgap to ensure this.

For DC analysis, sweep temperature and view the bandgap output versus temperature graph. You should see a parabolic curve to indicate that your bandgap is functioning.

As for stability check, do u have any negative feedbacks in your circuit? (Eg: error amplifier to maintain equal voltages at the PTAT branch) If you do then you will need to run AC analysis to check for the phase margin and loop gain of the feedback.

Hope this helps

Rgds,
svraj

 

[letan]

Hi all,
When you design a bandgap reference, PSRR is large or small is good. And why?

Thanks,

Regards,

 

[sar_vm]

You should probably do Monte Carlo simulation as well to check whether you meet the given accuracy requirements

 

[ashish_chauhan]

Hi

A high psrr is definitly good... to reject noise on the BGR output.
b'coz this noise will directly effect the performance of the circuit which uses the reference voltage( ADC DAC Voltage regulators).

For AC analysis( stability purpose) refer to the figure attached.

Hope this HELPS!!!!