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Design >> Analog Design >> Area efficient BGR
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Message started by misc on Apr 21^st, 2009, 5:43am

Title: Area efficient BGR
Post by misc on Apr 21^st, 2009, 5:43am

Dear Forumites,

I have requirement to implement a bandgap voltage reference with very small area being used. I doubt whether it is possible to implement BGR using very less doides so that we can reduce the area. Also i am worried about the accuracy with less doides. Please suggest some architectures to suit my requirement.

Thanx in advance
raags

Title: Re: Area efficient BGR
Post by vivkr on Apr 22^nd, 2009, 1:48am

Hi there,

There is of course a certain lower limit which you cannot break through. However there are ways, and some or all may be applicable depending on your technology and how well it is modelled:

1. The primary source of inaccuracy is the mismatch in the current mirrors and the amp used in the bandgap. Use chopping to eliminate the effect of this.

2. Use the smallest ratio of BJTs/diodes that gives sufficiently good performance. This way you save area.

3. Use circuit techniques that allow you to share the BJT collector. This way, you can place them all in the same well saving considerable area.

Finally, it depends on the accuracy/noise requirements and the kind of components you have available in your process, but I have used the above (even without 3) to make compact bandgaps with very good intrinsic accuracy.

Regards,

Vivek