Noise floor reduction in image sensors

Abstract

An image sensor array including a first plurality of unit cells coupled to a first sense amplifier, and a second plurality of unit cells coupled to a second sense amplifier, where the first plurality and the second plurality are substantially electrically isolated from each other.

What is claimed is:  
     
         1 . An image sensor array comprising: 
 a first plurality of unit cells coupled to a first sense amplifier; and    a second plurality of unit cells coupled to a second sense amplifier, wherein said first plurality and said second plurality are substantially electrically isolated from each other.    
     
     
         2 . An image sensor array according to  claim 1 , wherein: 
 each of said first and second pluralities of unit cells comprises at least one column line.    
     
     
         3 . An image sensor array according to  claim 2 , wherein: 
 said unit cells am arranged in two or more clusters of two or more of said unit cells each, and    said unit cells within each of said clusters are coupled to a cluster line which is coupled to said column line.    
     
     
         4 . An image sensor array according to  claim 3  wherein only one of said clusters is actively connected to said column line at any given time.  
     
     
         5 . An image sensor array according to  claim 1  wherein said unit cells are direct injection unit cells.  
     
     
         6 . An image sensor array according to  claim 1  wherein said first plurality and said second plurality are substantially electrically isolated from each over by at least 10M Ohms.  
     
     
         7 . An image sensor array comprising: 
 a plurality of columns, each column comprising a plurality of unit cells coupled to a column line; 
 a first sense amplifier coupled to a first plurality of said unit cells in each of said columns; and  
 a second sense amplifier coupled to a second plurality of said unit cells in each of said columns,  
 wherein said first and second pluralities of of said unit cells in each of said columns are substantially electrically isolated from each other.  
   
     
     
         8 . An image sensor array according to  claim 7  wherein each of said columns comprises a plurality of clusters, each cluster comprising two or more of said unit cells coupled to a cluster line which is coupled to said column line.  
     
     
         9 . An image sensor array according to  claim 7  wherein only one of said clusters is actively connected to said column line at any given time.  
     
     
         10 . An image sensor array according to  claim 7  wherein said unit cells are direct injection unit cells.  
     
     
         11 . An image sensor array according to  claim 7  wherein said first plurality and said second plurality are substantially electrically isolated from each other by at least 10M Ohms.  
     
     
         12 . A method for reducing noise floor in an image sensor, the method comprising: 
 sensing a first plurality of unit cells with a first sense amplifier; and    sensing a second plurality of unit cells with a second sense amplifier.    
     
     
         13 . A method according to  claim 12  wherein either of said sensing steps comprises sensing different subsets of said unit cells at different times.  
     
     
         14 . A method according to  claim 12  wherein either of said sensing steps comprises sensing mutually exclusive subsets of said unit cells at different times.  
     
     
         15 . A method according to  claim 12  wherein each of said sensing steps comprises sensing its associated plurality of unit cells in substantial electrical isolation from the other said plurality of unit cells.  
     
     
         16 . A method according to  claim 12  wherein each of said sensing steps are performed alternatingly.  
     
     
         17 . An image sensor array comprising: 
 a first plurality of unit cells coupled to a first sense amplifier; and    a second plurality of unit cells coupled to a second sense amplifier, wherein said first plurality and said second plurality are substantially electrically isolated from each other; wherein: 
 each of said first and second pluralities of unit cells comprises at least one column line.  
   
     
     
         18 . An image sensor array comprising: 
 a first plurality of unit cells coupled to a first sense amplifier; and    a second plurality of unit cells coupled to a second sense amplifier, wherein said first plurality and said second plurality are substantially electrically isolated from each other; wherein: 
 said unit cells are arranged in two or more clusters of two or more of said unit cells each, and  
 said unit cells within each of said clusters are coupled to a cluster line which is coupled to said column line.  
   
     
     
         19 . An image sensor array comprising: 
 a first plurality of unit cell means coupled to a first sense amplifier; and    a second plurality of unit cell means coupled to a second sense amplifier, wherein said first plurality and said second plurality are substantially electrically isolated from each other.    
     
     
         20 . A method for reducing noise floor in an image sensor, the method comprising: 
 sensing a first plurality of unit cells with a first sense amplifier; and    sensing a second plurality of unit cells with a second sense amplifier;    wherein each of said sensing steps comprises sensing its associated plurality of unit cells in substantial electrical isolation from the other said plurality of unit cells.    
     
     
         21 . A method for reducing noise floor in an image sensor, the method comprising: 
 sensing a first plurality of unit cells with a first sense amplifier; and    sensing a second plurality of unit cells with a second sense amplifier;    wherein said sensing steps include at least sensing different subsets of said unit cells at different times.