2.5 Voltage bandgap reference

[jerry.tran007]

Dear all,

I am doing my project about delta sigma modulation, it is needed a bandgap reference circuit for 2.5 voltage (because when changing VDD, my output is changed).

Is it possible for 2.5V bandgap circuit ? (my VDD is 3.3, using 0.13um tech).

Please help me.

 

[agreatstar]

Why dont u simply use a reverse biased zener?

 

[kam1787]

there are also ICs that provide a voltage reference.................

 

[Teddy]

I think in this case you would be better off with LDO-like structure. So make nice flat bgap and feed it as reference to ldo - this way you will have flat voltage over temp. You can generate 2.5V directly if you dump current reference to resistors - but I would think you will have a bit problem to compensate it over temp.

 

[kam1787]

If the supply voltage is very stable, then using a resistor divider to get the reference voltage is feasible. Using Metal Film Resistors would alleviate much of the temperature drift.

 

[jerry.tran007]

because I design using CMOS transistor, I cant use another IC. my VDD is requred about 3 to 3.6V, so I cant use resistor divided too.

Dear Mr Teddy,
do you have any idea about LDO circuit or any paper for beginner? I never design bandgap circuit before.

 

[kam1787]

because I design using CMOS transistor, I cant use another IC. my VDD is requred about 3 to 3.6V, so I cant use resistor divided too.

I do not understand your reply at all.

 

[betwixt]

I think this reference voltage is needed "on chip", it sounds like the post should really be in the "Analog IC Design and Layout" section.

Brian.