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 Title: |
US5693968:
Bi-directional, fast-timing, charge coupled device
[ Derwent Title ]
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| Country: |
US United States of America
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| Inventor: |
Cherry, Michael L.; Baton Rouge, LA
Ellison, Steven B.; Baton Rouge, LA
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| Assignee: |
Board of Supervisors of Louisiana State University and Agricultural and Mechanical College, Baton Rouge, LA
other patents from LOUISIANA STATE UNIVERSITY (343025) (approx. 62)
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| Published / Filed: |
1997-12-02
/ 1996-07-10
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| Application Number: |
US1996000677825
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| IPC Code: |
Advanced:
H01L 27/148;
Core:
more...
IPC-7:
H01L 27/148;
H01L 29/768;
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| ECLA Code: |
H01L27/148C;
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| U.S. Class: |
Current:
257/231;
257/239;
257/240;
257/241;
257/E27.154;
Original:
257/231;
257/239;
257/240;
257/241;
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| Field of Search: |
257/231,239,240,241
365/183
348/300,301,303
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| Government Interest: |
The development of this invention was partially supported by the Government under grant number NAGW-3744 awarded by the National Aeronautics and Space Administration, and under contract number NASA/LEQSF(1994-97)-IMP-02 from the Louisiana Board of Regents. The Government has certain rights in this invention.
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| Priority Number: |
| 1996-07-10 |
US1996000677825 |
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| Abstract: |
A fast-timing bi-directional charge coupled device ("CCD") is disclosed. The CCD operates at a much faster overall rate than conventional CCD's, while paradoxically slowing down the readout rate of the pixels. Lower power consumption is required, less heat is generated, thermal noise is lower, and digital noise is lower. The novel CCD is capable of 10-25 µsec timing resolution (or even faster). The configuration entirely eliminates the (formerly) rate-determining step of transferring data "horizontally" from the "top" of the CCD columns. Instead, the charges on columns are transferred either "up" or "down" in an alternating manner. For example, the charges in odd-numbered columns might be transferred one row "up" with each clock cycle, and charges in even-numbered columns might be transferred "down." This alternating charge transfer architecture is termed "bi-directional." There is no "horizontal" transfer of data off the chip; rather, each column outputs to a separate amplifier, preferably located on-chip. There is no need for a shutter in a low flux setting, although a shutter could be used for a high flux application. Without a shutter, the readout from each column is continual, without interruption; i.e., there is no "dead time" when light is not being detected. Assuming that light impinges on adjacent pixels in at least two different columns, the position and time of incoming light is reconstructed from the readouts of adjacent columns. The position of the impinging light is determined as the midpoint of readouts from adjacent columns; and the time of light arrival is proportional to the difference in readout from the adjacent columns. Unlike a conventional CCD, in a fast-timing, bi-directional CCD the clock time equals the time resolution of the overall image. Thus a relatively slow clock time of 10 µsec provides a very fast image time resolution of 10 µsec. In comparison to the 30 msec time resolution that is characteristic of conventional CCD's, the fast-timing bi-directional CCD can have a time resolution at least three orders of magnitude faster. The need for fast horizontal clocking is eliminated, as is the need for cooling. The fastest existing conventional CCD's can have a readout rate of about 106 pixels per second. The novel fast-timing CCD's can have a readout rate of 107 pixels per second, or even higher. Although the readout architecture of the novel fast-timing bi-directional CCD's is new, no new fabrication technologies are needed to construct the novel CCD's.
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| Attorney, Agent or Firm: |
Runnels, John H. ;
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| Primary / Asst. Examiners: |
Ngo, Ngan V.;
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| Maintenance Status: |
E2 Expired Check current status
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| INPADOC Legal Status: |
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| Family: |
None
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First Claim:
Show all 16 claims |
We claim:
1. A charge coupled device for converting photons or charged particles that impinge on said device into a signal; said device comprising a plurality of columns of semiconductor pixels, and a plurality of amplifiers, wherein:
- (a) each column of said pixels outputs to one of said amplifiers;
- (b) each said amplifier receives output from one or more columns of said pixels;
- (c) each said pixel is capable of producing a free charge in response to impinging photons or charged particles;
- (d) each said pixel is capable, in response to a clock signal generated either internally in said device or externally to said device, of transferring any free charge on said pixel to a selected neighboring element, wherein a neighboring element is an adjacent pixel in the same column, or is said amplifier corresponding to said column for a pixel that is at the end of said column nearer to said column's amplifier;
- (e) each pixel is capable of receiving a free charge from a neighboring pixel in the same column and storing that charge until a clock signal to transfer the free charge is received; except that this limitation (e) need not be satisfied by a pixel that is on the end of a column that is most distant from said column's amplifier;
- (f) the free charges within each column are all transferred in the same direction in response to a clock signal; and the free charges in adjacent columns are transferred in opposite directions relative to one another; so that if the free charges in column n are transferred "up," the free charges in column n+1 are transferred "down," wherein n is a positive integer less than the total number of columns;
- (g) said amplifier corresponding to each of said columns is connected to the pixel at the end of said column that is in the direction in which the free charges are transferred; so that said amplifier is connected to the "top" pixel in a column in which the free charges are transferred "up"; and said amplifier is connected to the "bottom" pixel in a column in which the free charges are transferred "down"; and wherein said amplifier amplifies the free charges transferred to said amplifier from the pixel to which said amplifier is connected, to output a signal;
whereby the position and timing of photons or charged particles impinging on said device may be determined by correlating the signals from adjacent columns; and whereby the time resolution of said device is equal to the time resolution of the clock signal.
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| Background / Summary: |
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| Drawing Descriptions: |
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| Description: |
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| Forward References: |
Show 7 U.S. patent(s) that reference this one
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| Foreign References: |
None
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| Other Abstract Info: |
DERABS G98-031870
DERG98-031870
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| Other References: |
J. Janesick et al., "History and Advancements of Large Area Array Scientific CCD Imagers," pp. 1-67 in S. Howell (ed.), Astronomical CCD Observing and Reduction Techniques, ASP Conf. Series, vol. 23 (1992).
M. Cherry et al., "Charge Coupled Devices with Fast Timing for Space Physics," pp.261-274 in MASS/AIRWATCH, Huntsville Workshop Report(Huntsville, Alabama Aug. 7-8, 1995).
P.Suni, "Custom Photodetector Arrays Meet Design Challenges," Laser Focus World(Apr. 1994).
Loral CCD442A Specification Sheet (1993).
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