Arbitrary function generator for APS injector synchrotron correction magnets

The arbitrary function generator (AFG) design is based on scanning out encoded data from a semiconductor memory, a first-in-first-out (FIFO) device. The data input consists of a maximum of 20 correction values specified within the acceleration window. Additional points between these values are then linearly interpolated to create a uniformly spaced 1000 data-point function stored in the FIFO. Each point, encoded as a 3-b value is canned out in synchronism with the injection pulse and used to clock the up/down counter driving the DAC (digital-to-analog converter). The DAC produces the analog reference voltage used to control the magnet current.<>