Current Sources and Voltage References

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Buried-zener voltage references

the LTZ1000. This was designed by Bob Dobkin, who had invented the buried-zener

topology in the first place. It provides a 7-volt output with less than 2 µV pk-pk noise, a

low drift of 0.05 ppm/°C, and a long-term stability of 2 ppm per month. These are

exotic specifications that have lasted two decades, but have yet to be matched by any

semiconductor maker anywhere. Even Xicor’s fabulous x60008B-50 FGA reference

(0.01% initial accuracy; 1 ppm/°C tempco; 10 ppm/month typical stability; and less

than 30 µV pk-pk low-frequency noise voltage) does not yet match the LTZ1000’s out-

standing specs.

Burr-Brown’s REF102 was another ...