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US RE43,639 E1Granted
Correcting charge transfer inefficiency in a charge coupled analog to digital converter
AssigneeKenet, Inc.
InventorsJeffrey D. Kurtze, Michael P. Anthony
Life of this patent
Estimating the term…
Abstract
A technique for correcting charge transfer inefficiencies in a Charge Coupled Device (CCD). The basic approach is to estimate the charge entering at a given stage in a CCD pipeline, and to then determine an estimate of the error introduced by the accumulated leftover charge that will be present at a second point, farther down the pipeline. The error is then corrected by injecting a correcting charge at a third point, farther still down the CCD pipeline. The invention is used, in one embodiment, to correct the output of a charge to digital converter, although principals of the invention may be used for other types of circuits.
Claims36
A method comprising:
- (a) estimating an amount of charge entering at a first selected stage in a multiple stage charge transfer pipeline;
- (b) determining an estimate of an accumulative error introduced at a second selected stage, the second selected stage further along the charge pipeline than the first selected stage;
- and
- (c) injecting a correction charge in the pipeline to adjust for the accumulative error, and
- wherein the step of (b) determining an estimate of the accumulative error further comprises estimating the accumulative error as a function of a per stage transfer efficiency error and the number of stages between the first selected stage and the second selected stage.
2 more elements
A method comprising:
- (a) estimating an amount of charge entering at a first selected stage in a multiple stage charge transfer pipeline;
- (b) determining an estimate of an accumulative error introduced at a second selected stage, the second selected stage further along the charge pipeline than the first selected stage;
- and
- (c) injecting a correction charge in the pipeline to adjust for the accumulative error, and
- wherein the size of the correction charge is fixed depending upon an expected charge transfer efficiency.
2 more elements
A method comprising:
- (a) estimating an amount of charge entering at a first selected stage in a multiple stage charge transfer pipeline;
- (b) determining an estimate of an accumulative error introduced at a second selected stage, the second selected stage further along the charge pipeline than the first selected stage;
- and
- (c) injecting a correction charge in the pipeline to adjust for the accumulative error, and
- wherein the step of determining the accumulative error additionally comprises:
- applying a predetermined calibration input charge to the first selected stage;
- determining an ideal expected charge that should occur at the second selected stage;
- measuring an actual measured charge at the second selected stage;
- and
- determining a difference between the ideal expected charge and the actual measured charge.
7 more elements
An apparatus comprising:
- (a) a first stage charge detector for determining an amount of charge entering at a first selected stage in the a multiple stage charge pipeline;
- (b) an accumulative charge error estimator, for estimating an accumulative charge error introduced at a second selected stage in the charge pipeline, the second selected stage further along the charge pipeline than the first selected stage;
- and
- (c) a correction charge injector, for injecting a correction charge in the multiple stage charge pipeline to adjust the accumulative charge error for charge transfer inefficiency;
- wherein the accumulative charge error estimator produces an accumulative charge error that is a function of a per stage transfer efficiency error and the number of stages between the first selected stage and the second selected stage.
2 more elements
An apparatus comprising:
- (a) a first stage charge detector for determining an amount of charge entering at a first selected stage in the a multiple stage charge pipeline;
- (b) an accumulative charge error estimator, for estimating an accumulative charge error introduced at a second selected stage in the charge pipeline, the second selected stage further along the multiple stage charge pipeline than the first selected stage;
- and
- (c) a correction charge injector, for injecting a correction charge in the charge pipeline to adjust the accumulative charge error for charge transfer inefficiency wherein the size of the correction charge is fixed depending upon the expected charge transfer efficiency.
1 more element
An apparatus comprising:
- (a) a first stage charge detector for determining an amount of charge entering at a first selected stage in the a multiple stage charge pipeline;
- (b) an accumulative charge error estimator, for estimating an accumulative charge error introduced at a second selected stage in the multiple stage charge pipeline, the second selected stage further along the charge pipeline than the first selected stage;
- and
- (c) a correction charge injector, for injecting a correction charge in the multiple stage charge pipeline to adjust the accumulative charge error for charge transfer inefficiency,
- wherein the accumulative error estimator further comprises:
- a calibration input circuit, arranged to couple a predetermined calibration input charge to the first selected stage;
- a detector, for measuring an actual measured charge at the second selected stage;
- and
- a difference detector, for determine a difference between an ideal expected charge and the actual measured charge.
6 more elements
A method comprising:
- (a) providing an input charge to a first selected stage of a multiple stage charge pipeline;
- (b) determining an estimate of an accumulative error in the multiple stage charge pipeline, the estimate being of an accumulative error introduced at a second selected stage in the pipeline, the second selected stage further along the charge pipeline than the first selected stage of the pipeline;
- and
- (c) injecting a correction charge in the pipeline to adjust for the accumulative error, and
- wherein the step of determining the accumulative error additionally comprises:
- applying a predetermined calibration input charge to the first selected stage;
- determining an ideal expected charge that should occur at the second selected stage;
- measuring an actual measured charge at the second selected stage;
- and
- determining a difference between the ideal expected charge and the actual measured charge.
7 more elements
An apparatus comprising:
- (a) a multiple stage charge pipeline having at least a first selected stage and a second selected stage further along the charge pipeline than the first selected stage;
- (b) an accumulative charge error estimator, for estimating an accumulative charge error introduced at the second selected stage in the charge pipeline;
- and
- (c) a correction charge injector, for injecting a correction charge in the pipeline to adjust the accumulative charge error for charge transfer inefficiency,
- wherein the accumulative error estimator further comprises:
- a calibration input circuit, arranged to couple a predetermined calibration input charge to the first selected stage;
- a detector, for measuring an actual measured charge at the second selected stage;
- and
- a difference detector, for determine a difference between an ideal expected charge and the actual measured charge.
6 more elements
An apparatus as in claim 36 wherein the charge to digital converter is a differential charge to digital converter that has a positive “p” side pipeline and a minus “m” side pipeline.
A method comprising:
- (a) providing an input charge to a first selected stage of a multiple stage charge pipeline;
- (b) determining an estimate of an accumulative error in the multiple stage charge pipeline, the estimate being of an accumulative error introduced at a second selected stage in the pipeline, the second selected stage further along the charge pipeline than the first selected stage of the pipeline;
- and
- (c) injecting a correction charge in the pipeline to adjust for the accumulative error, and
- wherein the step of determining an estimate of the accumulative error additionally comprises estimating the accumulative error as a function of a per stage transfer efficiency error and the number of stages between the first selected stage and the second selected stage.
2 more elements
An apparatus comprising:
- (a) a multiple stage charge pipeline, connected to receive a charge;
- (b) a charge detector for determining an amount of charge entering at a selected stage in the multiple stage charge pipeline;
- (c) a charge corrector, for providing a correction charge to the multiple stage charge pipeline at a stage which is further along the pipeline than the selected stage, the correction charge adjusting for a charge transfer inefficiency, and wherein the size of the correction charge is fixed depending upon an expected charge transfer efficiency across multiple stages of the charge pipeline.
Dependencies are inferred from the claim text.