Patent ID: 6998834
Filing Date: 2006-02-14
Classification: G01R

Abstract:
1. A method for reducing drift in a step stimulus provided to a sampling system comprising the steps of: a) setting a calibration repetition rate; b) acquiring step stimulus waveform samples at a first sample interval and determining a mid-crossing point in a step stimulus edge correlated in time; c) setting a baseline acquisition window, acquiring step stimulus waveform samples and determining a base line mean over the baseline acquisition window; d) setting a step stimulus edge acquisition window centered on the mid-crossing point in the step stimulus edge correlated in time, acquiring step stimulus waveform samples at a second sample interval smaller than the first sample interval, and determining a mid-crossing point in a step stimulus edge correlated in time and a rise time of the step stimulus edge over a selected portion of the step stimulus edge; e) setting a step stimulus edge acquisition window based on the rise time of the step stimulus edge, acquiring step stimulus waveform samples at a third sample interval smaller than the second sample interval, and determining a mid-crossing point in a step stimulus edge within the acquisition window correlated in time; f) storing the mid-crossing point in a step stimulus edge in step d) as the reference mid-crossing point and the current mid-crossing point; g) adjusting an initial strobe delay interval in the sampling system using the difference between the reference mid-crossing time and the current mid-crossing time; h) acquiring acquisition cycles of TDR/TDT waveform samples equal to the repetition rate using the adjusted initial strobe delay interval; i) performing a further step stimulus stabilization calibration on a new set of acquired step stimulus waveform samples using steps b), c), d), e) and f) to generate a new current mid-crossing time; and j) repeating steps g), h), and i).