Data processing: measuring – calibrating – or testing – Calibration or correction system – Circuit tuning
Reexamination Certificate
2006-12-05
2006-12-05
Wachsman, Hal (Department: 2857)
Data processing: measuring, calibrating, or testing
Calibration or correction system
Circuit tuning
C702S086000, C702S078000, C702S079000, C341S126000, C341S120000, C341S155000
Reexamination Certificate
active
07146283
ABSTRACT:
A calibration unit and technique for calibrating A/D systems (e.g., data acquisition devices) using a pulse-width modulation (PWM) circuit to reduce nonlinearity. The calibration unit may be coupled to an analog-to-digital module (ADM) of the A/D system. The PWM circuit may generate a calibration signal with intentional ripple, which may exercise a region of a transfer curve of the ADM to reduce local nonlinearities in measurements associated with the calibration of the system. Pulse trains of varying frequency and duty cycle may be generated to sweep the PWM circuit through an ADM range and to calculate an ADM linearity correction function, which may be used to perform gain and offset correction with respect to a best-fit line through an ADM transfer curve to reduce large signal nonlinearities. The PWM circuit may include a resistor divider circuit including a plurality of taps to calibrate small input ranges.
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U.S. Appl. No. 09/665,990, filed Sep. 20, 2000, by Paul Packebush and Costa Ilic.
Daigle Clayton H.
Regier Christopher G.
Sjoboen Lauren R.
Wangsanata Antony
Hood Jeffrey C.
Lewin Mario J.
Meyerstons Hood Kivlin Kowert & Goetzel, P.C.
National Instruments Corporation
Wachsman Hal
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