| 摘要 |
In a variable delay circuit calibrating method in which the state of connection of M delay stages connected in cascade through multiplexers and weighted differently is controlled by a control signal value to generate a calibrated amount of delay corresponding to a nominal amount of delay Ds which varies in a predetermined minimum nominal delay step ds, the method comprises the steps of: dividing an amount of delay Di measured for each given control signal value CCi by the minimum nominal delay step ds of a variable delay circuit; calculating first and second errors, Rk=Di-dsk and Rk+1=ds-Rk, between the value k of an integral part of the resulting quotient and two adjoining nominal amounts of delay Dsk and Dsk+1; making a check to determine if the first error Rk is smaller than an error held in a k-th row of a calibration table in correspondence with a nominal set signal value CS=k; if so, writing the first error Rk and the corresponding control signal value CCi over the existing values in the column of the k-th row of the calibration table; making a check to determine if the second error Rk+1 is smaller than an error held in a (k+1)-th row of the calibration table in correspondence with a nominal setting signal value CS=k+1; and, if so, writing the second error Rk+1 and the corresponding control signal value CCi over the existing values in the column of the (k+1)-th row of the calibration table. By repeatedly executing these steps for i=0 to i=2M-1, control signal values, which minimize errors between delay times of the variable delay circuit and the nominal amounts of delay, are generated in O-th to K-th rows of the calibration table in correspondence with the respective nominal setting signal values CS.
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