Photodiode active pixel sensor with shared reset signal row select

• US 6,218,656 B1
• Filed: 12/30/1998
• Issued: 04/17/2001
• Est. Priority Date: 12/30/1998
• Status: Expired due to Term

• Current Assignee: Omnivision Technologies Incorporated (Will Semiconductor Co., Ltd. Shanghai)
• Original Assignee: Eastman Kodak Company
• Inventors: Guidash, Robert M.
• Primary Examiner(s): Lee, John R.
• Assistant Examiner(s): PYO, KEVIN K
• Application Number:
  US09/223,608
• Time in Patent Office: 839 Days
• Field of Search: 250/208.1, 250/214.1, 257/291, 257/292, 257/443, 257/444, 257/431, 257/448, 348/300, 348/301, 348/308
• US Class Current: 250/208.1
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 25/766 comprising control or output lines used for a plurality of functions, e.g. for pixel output, driving, reset or power

Abstract

An active pixel sensor having a plurality of pixels arranged in rows and columns that are read out of the active pixel sensor in a sequential order of rows with each of the pixels having a photodiode as the photodetecting element. The row that is currently being read has an amplifier within each of the pixel in that row operatively connected to a column signal bus by a reset transistor configuration. A floating diffusion within each pixel is operatively connected to the reset transistor within the pixel such that the reset gate on the reset transistor for the row of photodetectors that is currently being read is also connected to the drain of the next row of pixels to be read resulting in a configuration that allows selection and deselection of rows via the reset busses. During selection of a particular row the amplifiers within each pixel of that row are operatively connected to the column signal bus while the amplifiers of the remaining rows are deselected and not connected to the column signal bus.

Claims

1. An active pixel sensor having a plurality of pixels arranged in rows and columns that are read out of the active pixel sensor in a sequential order of rows with at least a plurality of the pixels comprising:

a photodiode photodetector in the row currently being read that is operatively connected to a charge to voltage conversion node;

a reset transistor associated with the same pixel as the photodiode photodetector that has a source that is connected to the charge to voltage conversion node;

a reset gate on the reset transistor connected to a present reset control buss and a drain on the reset transistor connected to a prior reset control buss of the row previously read;

an amplifier operatively connected to the charge to voltage conversion node.

2. The invention of claim 1 wherein the source of the reset transistor is also the voltage conversion node.

3. The invention of claim 1 wherein the charge to voltage conversion node is a floating diffusion.

4. The invention of claim 1 wherein the amplifier is a source follower amplifier.

5. The invention of claim 1 wherein application of a first predetermined signal to the prior reset control buss connected to the present reset drain and, and a second predetermined signal to the present reset control buss resets the charge to voltage conversion nodes of the row presently being read.

6. The invention of claim 5 wherein the process of resetting the charge to voltage conversion node also selects the row presently being read.

7. The invention of claim 5 further comprising:

an output signal column buss for each of the columns that is operatively connected to the amplifiers for photodetectors in that column; and

the application of the first and second predetermined signals connects the amplifiers of the row currently being read to the output signal column buss.

8. The invention of claim 1 wherein application of a first predetermined signal to the prior reset control buss connected to the present reset drain and, and a second predetermined signal to the present reset control buss sets the charge to voltage conversion node to a predetermined potential that disables the amplifiers of the row previously read.

9. The invention of claim 8 wherein the process of disabling the row previously read deselects the row previously read.

10. The invention of claim 8 further comprising:

an output signal column buss for each of the columns that is operatively connected to the amplifiers for photodetectors in that column; and

the application of the first and second predetermined signals disconnects the amplifier of the row previously read from the output signal column buss.

11. A method of forming an active pixel sensor comprising the steps of:

providing a semiconductor substrate having a plurality of pixels arranged in rows and columns such that the rows can be read out sequentially; and

creating at least a portion of the pixels such that there is a present reset buss and a prior reset buss that are associated with at least one designated row within the portion and are operative in a first combination to reset the pixels in the designated row which results in selection of the designated row to be read and operative in a second combination to deselect the pixels in the designated row subsequent to the designated row being read.

12. The method of claim 11 wherein the step of creating further comprises:

creating the portion wherein each of the pixels in the designated row have an amplifier that as a first result of the first combination the amplifier is connected to a column buss; and

as a second result of the second combination the pixels in the designated row do not have their amplifiers connected to the column buss.