Fast BICMOS active-pixel sensor cell with fast NPN emitter-follower readout

• US 6,297,492 B1
• Filed: 01/06/1998
• Issued: 10/02/2001
• Est. Priority Date: 01/06/1998
• Status: Expired due to Fees

• Current Assignee: Intel Corporation
• Original Assignee: Intel Corporation
• Inventors: Clark, Lawrence T.
• Primary Examiner(s): Le, Que T.
• Assistant Examiner(s): Luu, Thanh X.
• Application Number:
  US09/003,477
• Time in Patent Office: 1,365 Days
• Field of Search: 250/214.R, 250/208.1, 250/214.1, 377/60, 257/292, 257/293, 348/301-304
• US Class Current: 250/214.00R
• 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 25/535 by dynamic region selection
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion
• CPC Class Codes: H04N 3/155 Control of the image-sensor operation, e.g. image processing within the image-sensor

Abstract

A read out circuit is provided. The read out circuit includes an emitter follower circuit (EFC) that receives information indicative of an intensity of light detected by a pixel of an active pixel sensor array. The EFC drives a value related to the information to a read out device when the pixel is accessed.

Claims

1. A read out circuit comprising:

an emitter follower circuit (EFC) to receive information indicative of an intensity of light detected by a pixel of an active pixel sensor array and to drive a value related to said information to a read out device when said pixel is accessed;

a first signal asserted to a pixel access device;

a second device to cut off said EFC when a second signal is asserted to said second device; and

the second signal is 180°

degrees in opposition of phase in relation to said first signal.

2. The read out circuit of claim 1, wherein the pixel access device is coupled to said pixel and to said EFC to pass said information from said pixel to said EFC when said pixel is accessed.

3. The circuit of claim 1, wherein the second device is adapted to cut off the EFC when said pixel is not accessed.

4. The circuit of claim 1, further including a reset circuit coupled to the read out device, the reset circuit is adapted to reset said read out device prior to access to said pixel.

5. The circuit of claim 1, said read out device is a capacitive device.

6. The circuit of claim 5, further comprising:

a circuit to reset said read out device which includes a third device to discharge said capacitive device and a control circuit to permit said third device to discharge said capacitive device prior to access to said pixel.

7. The read out circuit of claim 1, said second signal derived from said first signal.

8. A read out circuit comprising:

a row switch device (RSD) to receive, from a pixel of a row of an active pixel sensor array, information indicative of an intensity of light detected by said pixel;

emitter follower circuit (EFC), coupled to said RSD, said RSD configured to drive said information to said EFC, said EFC configured to drive a value related to said information to a read out device when said row of pixels is accessed;

a first signal asserted to a pixel access device; and

a second device to cut off said EFC when a second signal is asserted to said second device, the second signal is 180°

degrees in opposition of phase in relation to said first signal.

9. In an active pixel sensor array a read out circuit comprising:

a row switch device (RSD) to receive from one pixel of a row of pixels of said active pixel sensor array information indicative of an intensity of light detected by said pixel;

BJT circuit coupled to said RSD, said RSD configured to pass said information to said BJT circuit, said BJT circuit configured to drive a value related to said information to a read out device when said row of pixels is accessed;

a first signal asserted to a pixel access device; and

a device to cut off said BJT when a second signal is asserted to said device to cut off said BJT wherein the second signal is 180°

degrees in opposition of phase in relation to said first signal.

10. The active pixel sensor array of claim 9, said read out circuit wherein the device is adapted to cut off the BJT when said pixel is not accessed.

11. The active pixel sensor array of claim 9, said read out circuit coupled to the read out device, the reset circuit is adapted to reset said read out device prior to access to said pixel.

12. The active pixel sensor array of claim 9, said read out device is a capacitive device.

13. The active pixel sensor array of claim 12, further including:

a reset circuit coupled to the read out device, the reset circuit is adapted to reset the read out circuit which includes a device to discharge said capacitive device and a control circuit to permit said device to discharge said capacitive device prior to access to said pixel.

14. The active pixel sensor array of claim 9, said RSD configured to pass said information to said read out device when the first signal is asserted to said RSD.

15. The active pixel sensor array of claim 9, said second signal derived from said first signal.

16. An imaging system comprising:

a control device;

an active pixel sensor array, coupled to said control device, said active pixel sensor array including an emitter follower circuit (EFC) to receive information indicative of an intensity of light detected by a pixel of an active pixel sensor array and to drive a value related to said information to a read out device when said pixel is accessed;

a post processing device coupled to said control device and to said active pixel sensor array;

a pixel access device coupled to said EFC to pass information from said pixel to said EFC when a first signal asserted to said pixel access device; and

a second device to cut off said EFC when a second signal is asserted to the second device, the second signal is 180°

degrees in opposition of phase in relation to the first signal.

17. The imaging system of claim 16, further including a pixel access device (PAD) coupled to said pixel and to said control device to pass said information to said EFC when said control device enables said PAD.

18. The imaging system of claim 16, wherein the second device is adapted to cut off the EFC when said pixel is not accessed.

19. The imaging system of claim 16, further including a reset circuit coupled to the read out device, the reset circuit is adapted to reset said read out device prior to access to said pixel.

20. The imaging system of claim 16, said read out device includes a capacitive device.

21. The imaging system of claim 20, said reset circuit includes a device to discharge said capacitive device and a control circuit to permit said device to discharge said capacitive device prior to access to said pixel.

22. The imaging system of claim 16, said second signal derived from said first signal.

23. A read out circuit comprising:

emitter follower circuit (EFC) to receive information indicative of an intensity of light detected by a pixel of an active pixel sensor array and to drive a value related to said information to a read out device when said pixel is accessed;

a pixel access device coupled to said EFC to pass information from said pixel to said EFC when a first signal asserted to said pixel access device; and

a device to cut off said EFC when a second signal is asserted to said device, said second signal is 180 degrees in opposition of phase in relation to said first signal.

24. The read out circuit of claim 23, said second signal derived from said first signal.

25. An imaging system comprising:

a control device;

an active pixel sensor array, coupled to said contol device, said active pixel sensor array including an emitter follower circuit (EFC) to receive information indicative of an intensity of light detected by a pixel of an active pixel sensor array and to drive a value related to said information to a read out device when said pixel is accessed;

post processing device coupled to said control device and to said active pixel sensor array;

a pixel access device coupled to said EFC to pass information from said pixel to said EFC when a first signal asserted to said pixel access device; and

a device to cut off said EFC when a second signal is asserted to said device to cut off, said second signal 180°

degrees in opposition of phase in relation to said first signal.

26. The imaging system of claim 25, said second signal derived from said first signal.