Amplification type solid-state image pickup device and driving method therefor

Abstract

A plurality of pixel groups X(n) each comprising a plurality of pixels are set, and switched capacitor amplification parts are provided in correspondence to the pixel groups, respectively. Each of the switched capacitor amplification parts has a charge detection node to which output terminals of the transfer transistors of a corresponding pixel group X(n) are connected in common, an amplification part, a reset transistor, a first capacitance element, and a select transistor. A load part common to the switched capacitor amplification parts is provided. The load part is combined with the amplification parts of the switched capacitor amplification parts to constitute inverting amplifiers, respectively. By means of the above constitution, it is capable of obtaining a noise-reduced, high-quality image and which allows transistor count per pixel to be cut, thus allowing the pixel size to be reduced.

1 . An amplification type solid-state image pickup device which comprises a plurality of pixels each having a photoelectric conversion element and a transfer transistor for transferring signal charge of the photoelectric conversion element, wherein signals derived from the respective pixels are amplified and outputted to a signal line common to the pixels, and wherein: 
 a plurality of pixel groups each comprising a plurality of pixels are set;    switched capacitor amplification parts are provided in correspondence to the pixel groups, respectively;    each of the switched capacitor amplification parts has a charge detection node to which output terminals of the transfer transistors of a corresponding one of the pixel groups are connected in common, an amplification part to which a signal on the charge detection node is to be inputted, a reset transistor connected between the charge detection node and an output terminal of the amplification part, a first capacitance element connected between the charge detection node and the output terminal of the amplification part, and a select transistor connected between the output terminal of the amplification part and the signal line; and    a load part common to the switched capacitor amplification parts is connected between the signal line and power supply of a specified voltage so as to be combined with the amplification parts of the switched capacitor amplification parts to make up inverting amplifiers, respectively.    
   
   
       2 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 the photoelectric conversion element is a buried photodiode.    
   
   
       3 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 the load part comprises a transistor serving as a constant-current load.    
   
   
       4 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 the load part comprises a diffusion layer in which impurities are diffused in a semiconductor.    
   
   
       5 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 a grounding terminal of each switched capacitor amplification part consists of a light-shielding interconnect pattern common to all the pixels.    
   
   
       6 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 the amplification part and the load part constitute a cascode type inverting amplifier.    
   
   
       7 . The amplification type solid-state image pickup device as claimed in  claim 1 , further comprising 
 a control part for controlling the transfer transistor and the switched capacitor amplification part so that an operation of reading a signal from the photoelectric conversion element via the transfer transistor is iterated for each of the pixels in each of the pixel groups.    
   
   
       8 . An amplification type solid-state image pickup device driving method for driving the amplification type solid-state image pickup device as defined in  claim 1 , the method comprising: 
 a first step of turning on the reset transistor of the switched capacitor amplification part to perform a reset operation;    a second step of, after the first step, turning on the select transistor and turning off the reset transistor to perform a read operation of only a reset level;    a third step of, after the second step, turning on the transfer transistor of the pixel to perform charge transfer from the pixel to the switched capacitor amplification part; and    a fourth step of, after the third step, turning off the transfer transistor and turning on the select transistor to perform a read operation of a signal level, wherein    operations of the first step to the fourth step are iterated for each of the pixels in each of the pixel groups.    
   
   
       9 . The amplification type solid-state image pickup device as claimed in  claim 1 , further comprising: 
 a second capacitance element whose one terminal is connected to the charge detection node; and    first boosting means connected to the other terminal of the second capacitance element and serving for deepening potential of the charge detection node by capacitive coupling via the second capacitance element.    
   
   
       10 . An amplification type solid-state image pickup device driving method for driving the amplification type solid-state image pickup device as defined in  claim 9 , the method comprising: 
 a first step of turning on the reset transistor of the switched capacitor amplification part to perform a reset operation;    a second step of, after the first step, turning on the select transistor and turning off the reset transistor to perform a read operation of only a reset level;    a third step of, after the second step, turning on the transfer transistor of the pixel, in a state that potential of the charge detection node has been deepened by the capacitive coupling via the second capacitance element by the first boosting means, to perform charge transfer from the pixel to the switched capacitor amplification part; and    a fourth step of, after the third step, turning off the transfer transistor and turning on the select transistor to perform a read operation of a signal level, wherein    operations of the first step to the fourth step are iterated for each of the pixels in each of the pixel groups, whereby the signal is read out from each of the photoelectric conversion elements of the pixel groups.    
   
   
       11 . The amplification type solid-state image pickup device as claimed in  claim 1 , wherein 
 terminals of the reset transistor and the first capacitance element included in the switched capacitor amplification part other than and opposite to their terminals connected to the charge detection node are connected to the signal line instead of the output terminal of the amplification part, and wherein    the amplification type solid-state image pickup device further comprises a second boosting means connected to the signal line and serving for deepening potential of the charge detection node by capacitive coupling via the first capacitance element.    
   
   
       12 . An amplification type solid-state image pickup device driving method for driving the amplification type solid-state image pickup device as defined in  claim 11 , the method comprising: 
 a first step of turning on the reset transistor of the switched capacitor amplification part to perform a reset operation;    a second step of, after the first step, turning on the select transistor and turning off the reset transistor to perform a read operation of only a reset level;    a third step of, after the second step, turning on the transfer transistor of the pixel, in a state that potential of the charge detection node has been deepened by the capacitive coupling via the first capacitance element by the second boosting means, to perform charge transfer from the pixel to the switched capacitor amplification part; and    a fourth step of, after the third step, turning off the transfer transistor and turning on the select transistor to perform a read operation of a signal level, wherein    operations of the first step to the fourth step are iterated for each of the pixels in each of the pixel groups.