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Design >> Analog Design >> Multiple bandgap reference in IC
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Message started by chase.ng on Apr 9^th, 2007, 5:00pm

Title: Multiple bandgap reference in IC
Post by chase.ng on Apr 9^th, 2007, 5:00pm

Hello all,

Is it better to have only 1 centralized bandgap reference circuit and use current mirror to bias other circuits on the chip? Or is it better to have separate reference for separate circuits on the chip?

There are some arguments regarding trade-off between reliability and power. Some argue that by using multiple bandgap, I will get better reliability becuase in case one of the bandgap fail, only one part of the IC will fail.

But how often do these bandgap references fail? Anyone encounter any problem with a bandgap reference before?

Thanks and Regards,
chase.

Title: Re: Multiple bandgap reference in IC
Post by ywguo on Apr 9^th, 2007, 7:09pm

Hi, Chase,

I prefer a single bandgap which generate all required voltages and currents. The bandgap output is often an indication that the chip functions when we test in lab or test for mass production.

Now bandgap design is very mature and reliable. So don't worry. Furthermore, a product cannot be deliver to customers if only one part of the IC fails. So separate bandgap reference on a chip makes nonsense.

Thanks
Yawei

Title: Re: Multiple bandgap reference in IC
Post by loose-electron on Apr 12^th, 2007, 8:50pm

One bandgap and current distribution of bias - total agreement here.

Also Power up and power down are more predictable if it is all under the control of one bias box.

The only exception here - some RF type chips where noise in the bias distribution system is critical.

Ergo, ae you fighting thermal noise in bias currents? Hopefully not, because current source are very noisy things in the LNA-Mixer corner of the world.