Comparator, solid-state imaging device, electronic apparatus, and driving method

Abstract

A solid-state imaging device that outputs a pixel signal having a signal level corresponding to charges generated by a photoelectric conversion includes a comparator. The comparator has a first amplifying unit with first and second transistors configured as a differential pair and provides a signal output by amplifying a difference of signals input to the gate electrodes of the first and second transistors. It also has a second amplifying unit that amplifies the signal output, a first condenser disposed between the gate electrode of the first transistor and a reference signal supply, a second condenser disposed between the gate electrode of the second transistor and pixel signal wiring that reads out the pixel signal, and a switching circuit that connects the reference signal supply to the pixel signal wiring.

What is claimed is: 
     
         1 . A solid-state imaging device comprising:
 a pixel that outputs a pixel signal having a signal level corresponding to charges generated by a photoelectric conversion;   a pixel signal wiring that reads out the pixel signal; and   a comparator including:
 a first amplifying unit that includes first and second transistors configured as a differential pair, and amplifies a difference of signals input to each of the gate electrodes of the first and second transistors to provide a signal output; 
 a second amplifying unit that amplifies the signal output from the first amplifying unit; 
 a first condenser that is disposed between the gate electrode of the first transistor and a reference signal supply unit which supplies a reference signal; 
 a second condenser that is disposed between the gate electrode of the second transistor and the pixel signal wiring which reads out the pixel signal; 
 a switching circuit that connects the reference signal supply unit to the pixel signal wiring. 
   
     
     
         2 . The solid-state imaging device according to  claim 1 , wherein the first amplifying unit includes a third transistor that is connected between the gate electrode of the first transistor and the drain of the first transistor. 
     
     
         3 . The solid-state imaging device according to  claim 2 , wherein the first amplifying unit includes a fourth transistor that is connected between the gate electrode of the second transistor and the drain of the second transistor. 
     
     
         4 . The solid-state imaging device according to  claim 3 , wherein the second amplifying unit includes a fifth transistor whose gate electrode is connected to the first amplifying unit. 
     
     
         5 . The solid-state imaging device according to  claim 4 , wherein the second amplifying unit includes a sixth transistor whose drain is connected to a drain of the fifth transistor and a source is connected to a predetermined voltage. 
     
     
         6 . The solid-state imaging device according to  claim 5 , wherein the second amplifying unit includes a seventh transistor that is connected between a gate electrode of the sixth transistor and the drain of the sixth transistor. 
     
     
         7 . The solid-state imaging device according to  claim 6 , wherein the second amplifying unit includes a third condenser that is connected a connection point of the gate electrode of the sixth transistor and a source of seventh transistor to the predetermined voltage. 
     
     
         8 . An electronic apparatus comprising:
 a solid-state imaging device including:   a pixel that outputs a pixel signal having a signal level corresponding to charges generated by a photoelectric conversion,   a pixel signal wiring that reads out the pixel signal, and   a comparator, the comparator including:
 a first amplifying unit that includes first and second transistors configured as a differential pair, and amplifies a difference of signals input to each of the gate electrodes of the first and second transistors to provide a signal output; 
 a second amplifying unit that amplifies the signal output from the first amplifying unit; 
 a first condenser that is disposed between the gate electrode of the first transistor and a reference signal supply unit which supplies a reference signal; 
 a second condenser that is disposed between the gate electrode of the second transistor and the pixel signal wiring which reads out the pixel signal; and 
 a switching circuit that connects the reference signal supply unit to the pixel signal wiring. 
   
     
     
         9 . The electronic apparatus according to  claim 8 , wherein the first amplifying unit includes a third transistor that is connected between the gate electrode of the first transistor and the drain of the first transistor. 
     
     
         10 . The electronic apparatus according to  claim 9 , wherein the first amplifying unit includes a fourth transistor that is connected between the gate electrode of the second transistor and the drain of the second transistor. 
     
     
         11 . The electronic apparatus according to  claim 10 , wherein the second amplifying unit includes a fifth transistor whose gate electrode is connected to the first amplifying unit. 
     
     
         12 . The electronic apparatus according to  claim 11 , wherein the second amplifying unit includes a sixth transistor whose drain is connected to a drain of the fifth transistor and a source is connected to a predetermined voltage. 
     
     
         13 . The electronic apparatus according to  claim 12 , wherein the second amplifying unit includes a seventh transistor that is connected between a gate electrode of the sixth transistor and the drain of the sixth transistor. 
     
     
         14 . The electronic apparatus according to  claim 13 , wherein the second amplifying unit includes a third condenser that is connected a connection point of the gate electrode of the sixth transistor and a source of seventh transistor to the predetermined voltage.