High resolution column-based analog-to-digital converter with wide input voltage range for dental X-ray CMOS image sensor

A method of implementing an imaging system comprising:

• sampling a first analog pixel signal representative of a first pixel on a first capacitor;
• sampling a second analog pixel signal representative of the first pixel on a second capacitor, wherein the second analog pixel signal is transmitted from a first input of a comparator to a second input of the comparator;
• and then
• coupling the first capacitor to the first input of the comparator, and to a first control voltage having a value representative of a dark pixel value;
• coupling the second capacitor to the second input of the comparator, and to a second control voltage having a value representative of the dark pixel value;
• and then
• decreasing the second control voltage by an initial voltage drop;
• then
• increasing the second control voltage through a first voltage range until the comparator operates in a linear manner.

A method of implementing an imaging system comprising:

• generating a first analog signal representative of a dark pixel level of the imaging system;
• applying the first analog signal to a plurality of column-parallel analog-to-digital converters (ADCs) along a first signal path;
• generating a second analog signal that increases with a single-slope during a pixel measuring phase of the imaging system;
• and
• applying a second analog signal to the plurality of column-parallel ADCs along a second signal path, which extends adjacent to the first signal path.