Digital imaging circuit and method

• US 6,734,897 B1
• Filed: 08/10/1999
• Issued: 05/11/2004
• Est. Priority Date: 08/10/1999
• Status: Expired due to Term

• Current Assignee: Aptina Imaging Corporation (ON Semiconductor Corporation)
• Original Assignee: Agilent Technologies, Inc.
• Inventors: Mentzer, Ray A.
• Primary Examiner(s): Garber, Wendy R.
• Assistant Examiner(s): Tillery, Rashawn N.
• Application Number:
  US09/371,745
• Time in Patent Office: 1,736 Days
• Field of Search: 348/181, 348/180, 348/175, 348/308, 348/302, 348/187, 250/208.1
• US Class Current: 348/180
• CPC Class Codes: H04N 17/002 for television cameras
• CPC Class Codes: H04N 25/617 for reducing electromagnetic interference, e.g. clocking noise
• CPC Class Codes: H04N 25/76 Addressed sensors, e.g. MOS or CMOS sensors

Abstract

An active pixel sensor (APS) circuit which provides enhanced test and signal processing capabilities. APSs usually include pixel cells arranged in an array of rows and columns. Selectably enableable coupling conductors are provided between principal conductors in the array to permit a signal on one principal conductors to propagate to another principal conductors. The principal conductors include row, reset and column conductors. Signal propagation for testing purposes and for normal mode operation are disclosed.

Claims

1. An active pixel sensor circuit, comprising:

a substrate;

a plurality of active pixel cells each cell including a photodiode provided on said substrate and arranged in at least a plurality of rows;

a plurality of first signal conductors each associated with a given row and coupled to the active pixel cells of that row; and

a plurality of selectably enableable coupling conductors, one provided between each of said plurality of first signal conductors, and each providing selectable coupling of the first signal conductor of one row to that of another.

2. The circuit of claim 1, wherein said selectably enableable coupling conductors are provided at alternating ends of said plurality of first signal conductors such that when said coupling conductors are enabled to conduct, a signal input to a first of said first signal conductors propagates in a generally serpentine manner through the remainder of the plurality of first signal conductors.

3. The circuit of claim 1, wherein said selectably enableable coupling conductors are provided at alternating ends of said plurality of first signal conductors such that a signal input to a first of said first signal conductors propagates in a first direction on that first of said first signal conductors, in a second direction on a second of said first signal conductors that is generally opposite of said first direction and in said first direction again on a third of said first signal conductors.

4. The circuit of claim 1, wherein at least some of said selectably enableable coupling conductors each include combinational logic and a test enable input, receipt of a correct polarity signal at said test enable input causing a signal on a preceding first signal conductor to be passed through said combinational logic to a subsequent first signal conductor.

5. The circuit of claim 1, wherein at least some of said selectably enableable coupling conductors include tri-state logic and a test enable input, receipt of a correct polarity signal at said test enable input causing a signal on a preceding first signal conductor to be passed through said tri-state logic to a subsequent first signal conductor.

6. The circuit of claim 1, wherein said first signal conductors are one of the group of signal conductors including reset signal conductors and row signal conductors.

7. The circuit of claim 1, comprising a plurality of second signal conductors each associated with a given row and coupled to the active pixel cells of that row;

and

a plurality of second selectably enableable coupling conductors, one provided between each of said plurality of second signal conductors, and each providing selectable coupling of the second signal conductor of one row to that of another.

8. The circuit of claim 7, wherein said first signal conductors are one of the group of signal conductors including reset signal conductors and row signal conductors, and said second signal conductors are the other of that group.

9. The circuit of claim 8, further comprising test logic coupled to said reset signal conductors and said row signal conductors, said test logic generating test data for one of the reset and row signal conductors that is the complement of test data for the other of the reset and row conductors.

10. The circuit of claim 1, wherein said first signal conductors are reset signal conductors and said circuit further includes reset signal enable logic coupled to said reset signal conductors that enables said selectably enableable coupling conductors and initiates a reset signal to start integration of input image data.

11. The circuit of claim 1, wherein said first signal conductors and said selectably enableable coupling conductors are arranged such that when a signal is input to a first of said first signal conductors and said coupling conductors are enabled, the input signal is sequentially propagated to the remaining first signal conductors in such a manner that a delay is realized before receipt of that input signal at each subsequent one of said first signal conductors.

12. The circuit of claim 11, wherein said delay is primarily a function of parasitic characteristics of the first signal conductors.

13. The circuit of claim 11, wherein said delay is less than approximately 25 ns per row.

14. The circuit of claim 11, wherein said delay is analog.

15. The circuit of claim 1, wherein said plurality of active pixel cells are further arranged in a plurality of columns and said circuit further includes:

a plurality of column conductors each associated with one of said pixel columns and coupled to the active pixel cells of that pixel column; and

a plurality of selectably enableable coupling circuits, at least one provided between each of said column conductors such that a signal on one column conductor is sensed on a subsequent column conductor when the intervening coupling circuit is enabled.

16. The circuit of claim 15, wherein when said plurality of selectably enableable coupling circuits are enabled, a signal on a first of said column conductors is sensed in a substantially serpentine manner through the remainder of said columns.

17. An active pixel sensor circuit comprising:

a substrate;

a plurality of active pixel cells each cell including a photodiode provided on said substrate and arranged in at least a plurality of rows;

a selectably enableable continuous conductor that is coupled to each of said active pixel cells and arranged such that a signal input to said selectably enableable continuous conductor when enabled is propagated in a substantially serpentine manner to said plurality of active pixel cells.

18. The circuit of claim 17, wherein said selectably enableable continuous conductor includes one of the group of conductors including reset signal conductors and row signal conductors.

19. An active pixel sensor (APS) circuit, comprising:

a substrate;

a plurality of active pixel cells each cell including a photodiode provided on said substrate and arranged in at least a plurality of columns;

a plurality of column conductors each associated with one of said pixel columns and coupled to the active pixel cells of that pixel column; and

a plurality of selectably enableable coupling circuits, at least one provided between each of said column conductors such that a signal on one column conductor is sensed on a subsequent column conductor when the intervening coupling circuit is enabled.

20. The APS circuit of claim 19, wherein when said plurality of selectably enableable coupling circuits are enabled, a signal on said first of said column conductors is sensed in a substantially serpentine manner through the remainder of said columns.

21. The APS circuit of claim 19, wherein each of said selectably enableable coupling circuits includes an active device.

22. The APS circuit of claim 19, further including a current source coupled to each column conductor.

23. A method of processing for an active pixel sensor circuit, comprising the steps of:

providing a plurality of active pixel cells each cell including a photodiode on a substrate that are arranged in at least a plurality of rows;

providing a plurality of first signal conductors each associated with a given row and coupled to the active pixel cells of that row; and

selectably enabling coupling conductors between each of said plurality of first signal conductors such that a signal on one first signal conductor is propagated to the subsequent first signal conductor.

24. The method of claim 23, further comprising the steps of:

providing said selectably enableable coupling conductors at alternating ends of said plurality of first signal conductors;

enabling said selectably enableable coupling conductors; and

progating a signal through said first signal conductors and said enabled coupling conductors in a substantially serpentine manner.