TABLE OF CONTENTS Reference circuits and linear regulators actually have much in common. In fact, the latter could be functionally described as a reference circuit, but with greater current (or power) output. Accordingly, almost all of the specifications of the two circuit types have great commonality (even though the performance of references is usually tighter with regard to drift, accuracy, etc.). In many cases today the support circuitry is included in the converter package. This is advantageous to the designer since it simplifies the design process and guarantees performance of the system.
Voltage references have a major impact on the performance and accuracy of analog systems. A 5 mV tolerance on a 5 V reference corresponds to 0.1% absolute accuracy which is only 10-bit accuracy. For a 12-bit system, choosing a reference that has a 1 mV tolerance may be far more cost effective than performing manual calibration, while both high initial accuracy and calibration will be necessary in a system making absolute 16-bit measurements. Note that many systems make relative measurements rather than absolute ones, and in such cases the absolute accuracy of the reference is not as important, although noise and short-term stability may be.
Temperature drift or drift due to aging may be an even greater problem than absolute accuracy. The initial error can always be trimmed, but compensating for drift is difficult. Where possible, references should be chosen for temperature coefficient and aging characteristics which preserve adequate accuracy over...
