Proportional step size tracking analog-to-digital converter

A new type of tracking analog-to-digital converter, which is capable of responding quickly to step changes in the input voltage, has been developed. The device produces an error signal which indicates the difference between the converter's state and the input signal level. This error signal is used to modify the converter's slew rate in such a way as to optimize convergence back to the tracking condition (i.e., the condition at which the converter's state accurately tracks the input signal). This error signal is also used to generate an accuracy code which indicates if the converter is accurately tracking the input signal, or if the converter is out of track, how many bits of the encoded data are actually significant. An eight-bit transient recorder was developed using the converter described above. The instrument was found to be capable of recording data at rates up to 10(6) points/s, and was observed to respond to step voltage changes within eight datum points.