Self-calibrating adaptive ranging apparatus and method

Abstract

Apparatus and method for calibrating an adaptive ranging A/D converter wherein a noise having known statistical properties is deliberately superposed on the reference DC signals used to calibrate the gain-ranging amplifier. The amplitude of the noise is chosen to be greater than at least one, and preferably several, least significant digits of the A/D converter at the lowest anticipated gain, yet preferably less than half the counting range of the converter at the highest gain. The reference DC signal levels are chosen to be spaced from the minimum and maximum count of the A/D at the lowest and highest anticipated gains by better than half the noise amplitude. A time average of a series of measurements of the noisy reference signals as amplified and digitized by the system are obtained. The statistical properties of the noise generator permits the system output corresponding to the reference signals to be determined to a greater accuracy than the resolution of the A/D, thereby allowing the gain and offset of the gain-ranging amplifier to be determined with greater precision than is possible by injecting noiseless DC signals alone.

Inventors:
Abrams; David (Somerville, MA), Curbelo; Raul (Lexington, MA), Turner; R. Brough (Newton, MA)

Order No: 
4,616,329
Patent Date: 
Tue, 10/07/1986