Charge transfer skimming and reset circuit
AssigneeRCA Corporation
InventorsWalter Frank Kosonocky, Elliott Samuel Kohn
Life of this patent
Estimating the term…
Abstract
The portion which exceeds a given level, of a charge signal present at a radiation sensor, is passed to a storage site via the conduction path beneath a gate electrode. The remainder of the charge signal is removed to a drain through the same conduction path, the radiation sensor being reset to a reference level in the process. The use of a common conduction path for setting both the charge signal "skimming" level and the reset level, improves the uniformity of the skimming process from one sensor to another.
Claims6
In a radiation sensing array including a semiconductor substrate, in combination:
- a radiation sensor responsive to radiation for storing a charge signal;
- a gate electrode insulated from said substrate and located adjacent to said sensor;
- a charge storage location;
- means, including means for applying a voltage at a first level to said gate electrode, for conducting that portion of the charge signal stored in said sensor which exceeds a given level, via a conduction path in the substrate adjacent to said gate electrode, to said charge storage location;
- a drain region;
- and
- means, including means for applying a voltage at a second level to said gate electrode, for conducting that portion which exceeds a second given level of the remainder of said charge signal stored in said sensor to said drain region via the same conduction path in said substrate through which the portion exceeding said given level of said charge was conducted, and for resetting said radiation sensor to a reference level dependent on said second level in the process.
In a charge skimming circuit which includes a radiation sensor for storing a charge in response to the radiation it receives:
- a gate controlled device having a conduction path in a semiconductor substrate and a gate electrode, responsive to a control voltage, insulated from said substrate and located adjacent said sensor;
- a charge storage site;
- means including said conduction path of said gate controlled semiconductor device for skimming that portion over a given level of the stored charge signal and conveying said skimmed portion via said conduction path to said storage site, said skimmed portion passing under said gate electrode in the process;
- a drain;
- and
- means including the conduction path of the same semiconductor device for removing to said drain via the same conduction path, as employed for skimming, the remainder of the charge signal and for setting the radiation sensor to a reference level in the process, said remainder passing under said gate electrode in the process.
Dependencies are inferred from the claim text.