Image sensing device comprising dummy pixel row and active pixel rows coupled to read-out column line, and using a high speed active pixel row read-out method that reduces settling time by precharging the column line during a dummy pixel row selection time between active pixel row selection times
An image sensing device includes a pixel suitable for outputting a pixel signal through a read-out line during a read-out section and a precharge block suitable for precharging the read-out line to a voltage level corresponding to an initial voltage level of the pixel signal during a row non-selection section adjacent to the read-out section.
1. A read-out method of an image sending device, comprising:
reading out a first pixel signal corresponding to a voltage level charged in a floating diffusion node of a first active pixel through a column line during a first row selection section;
precharging, by using a dummy pixel, a column line to a voltage level corresponding to a reset level of pixel signals during a dummy row selection section;
charging a floating diffusion node of a second active pixel with a predetermined voltage in advance during the dummy row selection section; and
reading out a second pixel signal corresponding to a voltage level charged in a floating diffusion node of the second active pixel through the column line during a second row selection section,
wherein the precharging of the column line includes:
charging a dummy floating diffusion node of the dummy pixel with the predetermined voltage; and
precharging the column line to the reset level of the pixel signals corresponding to a voltage level charged in the dummy floating diffusion node, and
wherein the charging of the dummy floating diffusion node of the dummy pixel is carried out from a latter portion of the dummy row selection section until an initial portion of the second row selection section.
2. A read-out method of an image sending device, comprising:
reading out a first pixel signal of a first active pixel of a plurality of active pixels coupled to a first row and a column line, through the column line during a first row selection time,
wherein the first row selection time includes a time from when a first selection control signal is enabled until the first selection control signal is disabled;
precharging the column line to a voltage level corresponding to a voltage level of a reset signal which is read out from the first active pixel, by using a dummy pixel having a same structure as an active pixel of the plurality of active pixels and which is coupled to the column line, while the first active pixel and a second active pixel are electrically disconnected during a section between the first row selection time and a second row selection time;
enabling a reset control signal ahead of a second selection control signal for a second active pixel such that a portion of an enabling section of the reset control signal overlaps a latter portion of an enabling section of a dummy selection control signal, and another portion of an enabling section of the reset control signal overlaps an initial portion of an enabling section of the second selection control signal; and
reading out a second pixel signal of the second active pixel coupled to a second row and the column line during the second row selection time, through the column line which is precharged to the voltage level of the reset signal which is read out from the first active pixel,
wherein the second row selection time includes a time from when the second selection control signal is enabled until the second selection control signal is disabled.