Demand for higher performance in mixed-signal circuits requires ever-better voltage references. But the highest-performance references of yesterday aren’t suitable, as they are generally simple products with few additional features. With the development of high-performance bandgap references, plus improvements in process technology, we can design IC products that have unprecedented performance as well as a host of features, including low dropout, wide supply range, excellent line and load regulation, high output current capability, low noise and low drift. In addition, they may have self-protection features such as current and thermal limiting, as well as fault-protection like reverse-supply protection. LT6654 is an example of a high performance voltage reference that has many of these features, but its performance is moderate, at 10ppm/C. Alternatively, LTC6655 has ultra-high performance, with 2ppm/C drift and 0.25ppm noise, the best of any voltage reference. LT6657 pushes the stability of LTC6655 ever further, with 1.5ppm/C drift, plus adds the features of LT6654, and a few of its own.