Multi-photodetector unit cell

Abstract

A multi-cell cluster which includes a plurality of light-detecting unit cells and a single charge-integration and readout circuitry. Typically, each of the cells produces charge representative of the detected light. The circuit may be shared by the plurality of unit cells, and used to read-out the charge in real-time. The cluster may also include a switch associated with each unit cell, such that each switch connects its associated unit cell to the circuit. The switch may also be controlled in a time-multiplexing manner. Each unit cell may include a photodetector, a photodiode, or a photogate. The circuit may include a shared storage device, a shared reset circuit, or a readout circuit. Typically, the shared storage device may be for accumulating the charge in the focal plane. The here-above described apparatus facilitates either static or dynamic, either local or global image resolution/sensitivity tradeoffs.

1 . A multi-cell cluster comprising: 
 a plurality of light detecting unit cells, each said cell producing charge representative of said detected light; and    a circuit shared by said plurality of unit cells, said circuit for reading-out said charge in generally real-time.    
     
     
         2 . A cluster according to  claim 1 , and also comprising a switch associated with each said unit cell, each said switch connecting its associated unit cell to said circuit, each said switch being controlled in a time-multiplexing manner.  
     
     
         3 . A cluster according to  claim 1 , wherein each said unit cell comprises one of the following: a photodetector, a photodiode, or a photogate.  
     
     
         4 . A cluster according to  claim 1 , wherein said circuit comprises a shared storage device for accumulating said charge in the focal plane.  
     
     
         5 . A cluster according to  claim 1 , wherein said circuit also comprises a shared reset circuit.  
     
     
         6 . A cluster according to  claim 1 , wherein said circuit also comprises a shared readout circuit.  
     
     
         7 . A sensing array comprising: 
 a multiplicity of clusters, said clusters comprising: 
 a plurality of unit cells for detecting light and producing charge representative of said light; and  
 a circuit shared by said unit cells for controlling the operation of said unit cells and accumulating said charge;  
 sampling lines each connected to a row of clusters for sampling said accumulated charge in said row; and  
 sensing lines each connected to a column of clusters for sensing said sampled charge present in said columns.  
   
     
     
         8 . An array according to  claim 7 , wherein said lines carry programming signals for controlling said plurality of unit cells.  
     
     
         9 . A method for operating an image sensor, the method comprising the steps of: 
 integrating charge from one or more unit cells of a cluster;    during said step of integrating, summing charge in a focal plane, said charge being from said at least one of unit cell; and    reading out said summed charge.    
     
     
         10 . A method according to  claim 9 , wherein said one or more unit cells are preprogrammed unit cells.  
     
     
         11 . A method according to  claim 9 , wherein the step of reading out comprises reading out said summed charge in real time.  
     
     
         12 . A method according to  claim 9 , wherein the step of integrating comprises the step of integrating in a time-multiplexing manner.  
     
     
         13 . A method according to  claim 9 , wherein said step of integrating comprises the step of integrating charge from each said unit cell separately.  
     
     
         14 . A method according to  claim 9 , wherein said step of integrating comprises the step of substantially simultaneously integrating charge from two or more of said unit cells.  
     
     
         15 . A method according to  claim 9 , wherein said step of integrating comprises the step of substantially simultaneously integrating charge from all of said unit cells in said cluster.  
     
     
         16 . A method according to  claim 9 , further comprising the step of combining said readout into a single image.  
     
     
         17 . A method according to  claim 9 , further comprising the step of dynamically controlling selection of the number of said one or more unit cells for said step of charge integrating.  
     
     
         18 . A method according to  claim 17 , wherein said step of dynamically controlling comprises the step of selecting said number of one or more unit cells depending on light conditions.  
     
     
         19 . A method according to  claim 17 , and wherein all of said steps are performed in generally real-time  
     
     
         20 . A method according to  claim 9 , further comprising the step of: 
 improving the signal to noise ratio of said image sensor by increasing the number of said one or more cells in said step of integrating.    
     
     
         21 . A method according to  claim 9 , further comprising the step of: 
 improving the resolution of said image sensor by decreasing the number of said one or more cells in said step of integrating; and    reading said cell separately in a time-multiplexing manner.