Patent ID: 6891487
Filing Date: 2005-05-10
Classification: H03M

Abstract:
1. A method for calibrating a switched capacitor array in a SAR data converter, which capacitor array includes a plurality of primary capacitors each having a common node plate interfaced to a common node and a switched plate interfaced to a switch that is operable to be switched between first and second reference voltages, comprising the steps of: providing a comparator having an input connected to the common node and a reference input connected to a comparator reference node for receiving a comparator reference voltage; in a first calibration step for calibrating a select one of the primary capacitors: in a second calibration step: providing a plurality of trim capacitors; and if, in the second calibration step, it was determined that the voltage on the common node was greater than the first voltage, then disposing one of the trim capacitors in parallel with the select one of the primary capacitors and then repeating the first and second calibrating steps.