Patent ID: 7460045
Filing Date: 2008-12-02
Classification: H03M

Abstract:
1. A calibration method for a multi-stage analog to digital (A/D) converter, each stage having an analog input, a digital output, an analog residue and a digital residue, a histogram of digital residue codes being used to correct a transfer characteristic of the stage for a given digital output, the method comprising: estimating a bound for a current histogram associated with a current digital output code, the estimated bound being used to estimate a discontinuity in the transfer characteristic; in response to a determination that a current digital residue occurs in the current histogram: comparing the estimated bound with a gross lock-up detection value and a fine lock-up detection characteristics; detecting whether a gross lock-up condition exists based on the comparison of the estimated bound with the gross lock-up detection value; restarting calibration in response to detection of the gross lock-up condition; in response to detection that there is no gross lock-up condition, detecting whether a fine lock-up condition exists by determining whether the current digital residue satisfies fine lock-up detection characteristics; in response to detection that there is no fine lock-up condition, modifying the estimated bound based on a comparison of the current digital residue with a fast lock value and a bound window; and removing the discontinuity in the transfer characteristic of the A/D converter based on the estimated bound.