A High Precision Waveform Generator

The microprocessor controlled waveform generator produces a piece-wise linear time dependent analog reference (± 10 VFS) for the Fermilab Saver Higher Order Correction Element power supplies. Up to 32 major linear segments can be programmed with end point amplitude resolution of 305 ¿V and time resolution of 6.5 ms. Major segments can be subdivided in up to 32 subsegments to achieve smoother slope transitions. The output of a high precision 16-bit D/A converter having 305 ¿V steps is further smoothed with circuitry whose output is an analog integrator that follows the centerline of these steps. Typical ripple (smoothness) errors are such that ¿V/VFS < 10-5/f, and for frequencies less than 1 KHz, output noise is less than 10 ¿Vp-p. Typical DC linearity over a 25°C temperature range is ±150 ¿V. Measured gain errors were 0.7 PPM/°C and zero stability was 2 ¿V/°C. The overall absolute accuracy of the generator is ±0.005% FS (± 500 ¿V).