resistor trimming in voltage reference

[liuyonggen_1]

1: could someone show me what the variation for worst case is about the output of the voltage reference without resistance trimming? That is, in general, how about the temperature coefficiency of the voltage reference without trimming?

2: if using trimming, does transistor also need trimming technology?

3: how many kinds of trimming techniques for resistance often are used in practice?

thanks a lot!

 

[mdanaie]

about 100ppm/ C refer to bandgap reference circuits