Active pixel sensor (APS) readout structure with amplification

• US 20050151869A1
• Filed: 12/28/2004
• Published: 07/14/2005
• Est. Priority Date: 06/15/1999
• Status: Active Grant

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Inventors: Andersson, Anders
• Granted Patent: US 7,557,844 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: H04N 25/60 Noise processing, e.g. detecting, correcting, reducing or removing noise
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

An active pixel sensor (APS) includes an array of individually addressable APS cells ad a pixel readout structure that includes an amplifier. The amplifier may have a two-branched structure and provide a gain of one or higher. Additional switches may be provided in the pixels to provide protection for pixel output transistors from voltage changes in the column line. Structure may also be provided for optional gain selection in the amplifier.

Claims

1-17. -17. (canceled)

18. A method of reading out a signal from an imager pixel in an imager device, said method comprising the acts of:

converting photo-generated charge in the pixel into a first voltage;

outputting the first voltage to a first amplifier branch; and

amplifying the first voltage in a second amplifier branch to form an amplified voltage.

19. The method of claim 18, further comprising the act of outputting the amplified voltage.

20. The method of claim 18, wherein said amplifying step applies a gain to the first voltage.

21. The method of claim 20, wherein the applied gain is a unity gain.

22. The method of claim 20, wherein the applied gain is a gain greater than one.

23. The method of claim 20, wherein said amplifying step comprises the act of switching in a gain altering element to amplify the first voltage with a second gain.

24. The method of claim 20, wherein said amplifying step comprises the act of enabling a gain altering element to amplify the first voltage with a second gain.

25. The method of claim 18 further comprising the act of substantially blocking unwanted voltage changes from being applied to an output transistor located in the first amplifier branch.

26. A method of reading out a signal from an imager pixel in an imager device, said method comprising the acts of:

converting photo-generated charge in the pixel into a first voltage;

outputting the first voltage to a first amplifier branch;

selecting a gain to be applied to the first voltage; and

applying the selected gain to first voltage in a second amplifier branch to form an amplified voltage.

27. The method of claim 26, further comprising the act of outputting the amplified voltage.

28. The method of claim 26, wherein the selected gain is a unity gain.

29. The method of claim 26, wherein the selected gain is a gain greater than one.

30. The method of claim 26, wherein said selecting step comprises the acts of:

generating a first gain; and

switching in a gain altering element to alter the first gain into a second gain.

31. The method of claim 26, wherein said selecting step comprises the acts of:

generating a first gain; and

enabling a gain altering element to alter the first gain into a second gain.

32. The method of claim 26 further comprising the act of substantially blocking unwanted voltage changes from being applied to an output transistor located in the first amplifier branch.