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US 8,941,528 B2Granted
Analog to digital conversion circuit, image sensing device having the same and method of driving image sensing device
AssigneeSK hynix Inc.
InventorGun-Hee Yun
Life of this patent
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Abstract
An analog-to-digital conversion circuit includes a reference current generating unit suitable for generating a reference current varied by a given level in a sampling stage, a ramp voltage generating unit suitable for generating a ramp voltage corresponding to the reference current, and a comparison unit suitable for comparing the ramp voltage with a voltage level of a pixel signal to output a comparison signal.
Claims19
An analog-to-digital conversion circuit comprising:
- a plurality of current sources sequentially activated in a plurality of sampling stages, each current source suitable for generating a reference current which is adjusted upward or downward by a different level in a corresponding sampling stage;
- a ramp voltage generating unit suitable for generating a ramp voltage corresponding to the reference current;
- and
- a comparison unit suitable for comparing the ramp voltage with a voltage level of a pixel signal to output a comparison signal,
- wherein the current source generates the reference current which is adjusted from a coarse level to a fine level according as the number of the sampling stage increases, and reflects a current level of the reference current corresponding a sampling result in a previous sampling stage on a next sampling stage.
2 more elements
An analog-to-digital conversion circuit comprising:
- a plurality of sinking units coupled between a ground voltage terminal and a reference node in parallel, each sinking unit suitable for generating a reference current corresponding to a bias signal at the reference node, in a corresponding sampling stage;
- a plurality of switching units suitable for selectively transferring the bias signal to one of the sinking units in response to a plurality of switching signals;
- at least one storage unit coupled to a node between the switching units and the sinking units, suitable for storing a voltage level of the bias signal;
- a ramp voltage generating unit coupled between a supply voltage terminal and the reference node, suitable for generating a ramp voltage corresponding to the reference current;
- a comparison unit suitable for comparing the ramp voltage with a voltage level of a pixel signal to output a comparison signal;
- and
- a control unit suitable for generating the switching signals in response to a plurality of step signals, which are sequentially activated at the sampling stages, and the comparison signal.
4 more elements
An image sensing device comprising:
- a pixel unit suitable for outputting a pixel signal with a level corresponding to incident light;
- a digital-to-analog converter suitable for generating a sampling current which is used in a sampling stage, and adjusted upward or downward in the sampling stage;
- and
- an analog-to-digital converter suitable for generating a digital signal corresponding to the pixel signal based on a reference current generated by mirroring the sampling current,
- wherein the analog-to-digital converter generates the reference current which is adjusted from a coarse level to a fine level according as a number of the sampling stage increases, and reflects a current level of the reference current corresponding a sampling result in a previous sampling stage on a next sampling stage.
2 more elements
An image sensing device comprising:
- a pixel unit suitable for outputting a pixel signal with a level corresponding to incident light;
- a first current mirroring unit suitable for mirroring a source current to generate a sampling current which is used in a sampling stage and adjusted upward or downward in the sampling stage in response to a control code;
- a second current mirroring unit suitable for generating a bias signal corresponding to the sampling current;
- a plurality of sinking units coupled between a ground voltage terminal and a reference node in parallel, each sinking unit suitable for generating a reference current corresponding to the bias signal at the reference node, in a corresponding sampling stage;
- a plurality of switching units suitable for selectively transferring the bias signal to one of the sinking units in response to a plurality of switching signals;
- at least one storage unit coupled to a node between the switching units and the sinking units, suitable for storing a voltage level of the bias signal;
- a ramp voltage generating unit coupled between a supply voltage terminal and the reference node, suitable for generating a ramp voltage corresponding to the reference current;
- a comparison unit suitable for comparing the ramp voltage with the pixel signal to output a comparison signal;
- and
- a control unit suitable for generating the switching signals in response to a plurality of step signals, which are sequentially activated at the corresponding sampling stage, and the comparison signal.
7 more elements
A method for driving an image sensing device, comprising:
- in a first sampling step, mirroring a source current to generate a sampling current which is adjusted downward by a first level in response to a control code, generating a ramp voltage corresponding to a reference current by mirroring the sampling current, and sampling a pixel signal outputted from a pixel based on the ramp voltage;
- and
- in a second sampling step, mirroring the source current to generate the sampling current which is adjusted upward by a second level in response to the control code, generating the ramp voltage corresponding to the reference current by mirroring the sampling current, and sampling the pixel signal based on the ramp voltage.
Dependencies are inferred from the claim text.