Dual sensitivity optical sensor
AssigneeMcDonnell Douglas Corporation
InventorsJohannes K. Notthoff, Rainer Zuleeg
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AssigneeMcDonnell Douglas Corporation
InventorsJohannes K. Notthoff, Rainer Zuleeg
Estimating the term…
A dual sensitivity photodetector comprising a central region comprising a relatively high sensitivity reach through avalanche photo diode and a surrounding region comprising a relatively lower sensitivity P-type intrinsic N-type photodiode is disclosed which possesses the advantages of a wide sensitivity range and a relative freedom from overload.
An integrated dual sensitivity photodetector implemented in a semiconductor material substrate comprising a central region comprising a relatively high sensitivity photodetector device and a surrounding region comprising a relatively lower sensitivity photodector device.
A solid state semiconductor dual sensitivity photodetector device comprising an intrinsic substrate having disposed on a first side a plurality of P+-type radial segments in an inner area substantially symmetrically surrounding a central point surrounded by a further plurality of P+-type radial segments in an outer symmetrically surrounding area, the outer area being isolated from the inner area by a moat, and having disposed on an opposite side of the device a first P-type area located directly opposite to and having substantially the same area as the inner area of the first side and a second N+-type area symmetrically located upon and completely covering the first P-type area, the N+-type area having substantially the same perimeter as the outer perimeter of the symmetrically surrounding outer area on the first side.
A solid state semiconductor dual sensitivity photodetector device comprising an intrinsic substrate having disposed on a first side a first P-type area in an inner area substantially symmetrically surrounding a central axis and a second N+-type area symmetrically located upon and completely covering the first P-type area, the effective radius of the N+-type area being greater than about 1.5 times the effective radius of the P-type area, and having disposed on an opposite side of the device a plurality of P+-type radial segments in an area symmetrically surrounding the central axis, the outer perimeter of the P+-type area being substantially the same as the outer perimeter of the N+-type area on the first side.
A photodetector circuit comprising:
A photodetector circuit comprising:
A photodetector circuit comprising:
Dependencies are inferred from the claim text.
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No related US applications are recorded in the indexed filing history.
The devices being sensitive to infrared, visible or ultraviolet radiation: the devices having only two potential barriers, e.g. bipolar…
The devices having only one potential barrier, e.g. photodiodes: the potential barrier being a PIN barrier
The devices having only one potential barrier, e.g. photodiodes: the potential barrier working in avalanche mode, e.g. avalanche photodiodes
For devices having potential barriers: for devices working in avalanche mode
Term ended 29 Sep 2000 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
This invention relates to photodetectors. Still more particularly, this invention relates to photoconductors which are composed of two different types of photodiodes.
2. Description of the Prior Art
FIG. 1 portrays the upper surface of the photodetector;
FIG. 2 is a cross-sectional view of the photodetector;
FIG. 3 is a schematic electrical diagram of one implementation of the photodetector;
As summarized above, this invention concerns an integrated photodetector comprising a high sensitivity central region surrounded by a lower sensitivity region. The integration of the two different photodetectors with different sensitivities into a single device provides the important advantages of noise reduction and adaptability to the disclosed device over single sensitivity prior art devices.
At present, the most useful high sensitivity photodetector device for utilization as the high sensitivity central region of the integrated photodetector is the reach through avalanche photodiode (RAPD). The RAPD device utilizes avalanche gain to achieve very high sensitivity. The RAPD device is located at the central region of the integrated photodetector in order to utilize its high sensitivity for initial target image acquisition and tracking for the small image sizes, typically less than 0.5 millimeters, encountered at ranges above three kilometers. The diameter of the RAPD region in this particular embodiment is approximately 1.0 millimeters.
The high sensitivity RAPD region is surrounded by a lower sensitivity photodetector region. The PIN (P-type, intrinsic, N-type) photodiode has been advantageously utilized for this purpose. As mentioned above, the lower sensitivity PIN photodetector becomes very useful at the closer target ranges below about three kilometers. As the image size impinging upon the integrated photodetector increases at the shorter ranges, the signal from the photodetector becomes dominated by the signal from the lower sensitivity PIN region and effectively overpowers any detrimental noise contributions from the high sensitivity RAPD central photodiode region. The relative contributions of the signals from the two different regions can be varied by varying the bias voltage across and RAPD region. The total width of the integrated photodetector is approximately three millimeters in this application, with the RAPD device accounting for the central one millimeter, and the PIN region accounting for the remainder of the integrated photodetector.