Active pixel sensor having intra-pixel charge transfer with analog-to-digital converter

An imaging device, comprising:

• a semiconductor substrate defining a plurality of pixel cell areas, and a signal handling area;
• each said pixel cell area comprising:
• a) a photogate;
• and
• b) a coupling section formed on said substrate adjacent said photogate, having a sensing node connected to receive a signal indicative of photogenerated charge from said photogate and at least one coupling stage, operating to transfer charge from said underlying portion of said substrate to said sensing node;
• d) a buffer transistor, operating to buffer signal from said sensing node, and a selection transistor, having a gate, operated to select said pixel;
• and
• e) an output node which receives signal only when said selection transistor is operated.

An imaging device comprising a focal plane array of pixel cells, each of said pixel cells including a monolithic semiconductor integrated circuit substrate, each of said pixel cells comprising:

• a) a photogate overlying a first portion of said substrate and operating to accumulate photo-generated charge in a first portion of said substrate that underlies said photogate;
• b) a charge transfer section, formed in said substrate adjacent said photogate, having a sensing node adjacent said photogate and at least one charge coupling stage, operating to transfer charge from said first portion of said substrate to said sensing node;
• c) an output node;
• and
• d) a transistor which selectively connects said sensing node to said output node,
• and further comprising a plurality of A/D converters, connected to said output nodes of a plurality of said pixel cells, but less than all of said pixel cells, so that less than all of said pixel cells are attached to said A/D converter.

A method of forming and using an imaging device, comprising:

• defining a plurality of pixel areas, each said pixel area covering a specified area of a charge accumulating substrate;
• configuring each of said plurality of pixel areas as a portion of said substrate,
• providing a photogate controlling a characteristic of each said portion of said charge accumulating substrate;
• providing a sensing node which senses charge in said portion of said charge accumulating substrate;
• selectively passing a value in said sensing node to an output node associating an A/D converter circuit with each of a plurality of unit groups of said output nodes of each pixel areas;
• and
• connecting each output node within each said unit group to each other and passing only one output therefrom to said A/D converter to thereby read a plurality of said unit groups in parallel.