CMOS imager for cellular applications and methods of using such

• US 7,701,497 B2
• Filed: 10/08/2003
• Issued: 04/20/2010
• Est. Priority Date: 05/29/2001
• Status: Active Grant

• Current Assignee: Transchip Israel Limited
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Antsiferov, Ilia, Voronov, German, Elmakias, Yair, Shnayder, Alexander, Furman, Ben, Fraenkel, Miriam, Galambos, Tiberiu C.
• Primary Examiner(s): Chan; Jason
• Assistant Examiner(s): Le; Tuan H
• Application Number:
  US10/474,798
• Publication Number:
  US 20050068436A1
• Time in Patent Office: 2,386 Days
• Field of Search: 348294-311, 348/241, 348/243, 348/245, 348/248, 250/208.1
• US Class Current: 348/294
• CPC Class Codes: H04N 11/20 Conversion of the manner in which the individual colour picture signal components are combined, e.g. conversion of colour television standards
• CPC Class Codes: H04N 17/002 for television cameras
• CPC Class Codes: H04N 23/70 Circuitry for compensating brightness variation in the scene
• CPC Class Codes: H04N 23/71 Circuitry for evaluating the brightness variation
• CPC Class Codes: H04N 23/73 by influencing the exposure time
• CPC Class Codes: H04N 23/745 Detection of flicker frequency or suppression of flicker wherein the flicker is caused by illumination, e.g. due to fluorescent tube illumination or pulsed LED illumination
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/67 applied to fixed-pattern noise, e.g. non-uniformity of response
• CPC Class Codes: H04N 25/745 Circuitry for generating timing or clock signals
• CPC Class Codes: H04N 25/75 Circuitry for providing, modifying or processing image signals from the pixel array
• CPC Class Codes: H04N 5/16 Circuitry for reinsertion of dc and slowly varying components of signal; Circuitry for preservation of black or white level
• CPC Class Codes: H04N 9/69 for modifying the colour signals by gamma correction controlling camera response for colour signals H04N23/83
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88

Abstract

Systems, methods and devices related to detecting and transmitting images. Imaging system and devices, as well as methods of using such that are provided herein include flicker detection and/or correction; and/or built-in self test associated with various analog circuitry in the imaging devices; and/or power reduction ability; and/or pixels with charge evacuation functionality; and/or parallel to serial conversion unit and associated serial output interface; and/or other advanced functionality.

Claims

1. A CMOS imager, wherein the CMOS imager comprises:

an image sensor;

a sub-sample control system, wherein the sub-sample control system is operable to identify one or more analog signals from the image sensor that are not processed;

a processing control system coupled to outputs of the image sensor, the sub-sample control system and a reference voltage; and

an analog processing circuit, configured to receive at least one of the reference voltage and one or more analog signals from the processing control system based on the output of the sub-sample control system, wherein the processing control system is operable to limit switching of the one or more inputs.

2. The CMOS imager of claim 1, wherein the analog processing circuit comprises a column amplifier, and wherein the one or more inputs are inputs to the column amplifier.

3. The CMOS imager of claim 1, wherein the analog processing circuit comprises a level shift circuit, and wherein the one or more inputs are inputs to the level shift circuit.

4. The CMOS imager of claim 1, wherein the analog processing circuit comprises a programmable offset circuit, and wherein the one or more inputs are inputs to the programmable offset circuit.

5. The CMOS imager of claim 1, wherein the processing control system is operable to maintain a common mode feedback loop of an amplifier associated with the analog processing circuit in an active state, while limiting switching of the one or more inputs.

6. The CMOS imager of claim 1, the CMOS imager further comprising:

a digital processing circuit, wherein the processing control system is further operable to disable the digital processing circuit.

7. A method for processing images in a power sensitive application including a CMOS imager having a pixel array and an analog processing circuit, the method comprising:

defining, by a sub-sample control system, a first portion and a second portion of the pixel array, wherein the first portion of the pixel array includes an output image area and the second portion of the pixel array includes a dropped image area;

receiving a pixel signal from the second portion of the pixel array; and

placing, by the sub-sample control system, the analog processing circuit in a standby mode when the analog pixel signal from the second portion of the pixel array is detected, wherein the analog pixel signal from the second portion of the pixel array is not processed.

8. The method of claim 7, wherein placing the analog processing circuit in the standby mode comprises:

limiting switching of one or more inputs to the analog processing circuit.

9. The method of claim 7, wherein placing the analog processing circuit in the standby mode comprises:

electrically coupling one or more inputs of the analog processing circuit to a static voltage, wherein switching of the analog processing circuit is reduced.

10. The method of claim 7, wherein placing the analog processing circuit in the standby mode comprises:

electrically coupling one or more inputs of the analog processing circuit to a static voltage, while maintaining switching associated with a common mode feedback loop of one or more amplifiers associated with the analog processing circuit, wherein switching of the analog processing circuit is reduced, and bias currents are reduced while maintaining the one or more amplifiers at its inertial state.

11. The method of claim 7, the method further comprising:

receiving a analog pixel signal from the first portion of the pixel array; and

placing the analog processing circuit in an operational mode, wherein the analog pixel signal from the first portion of the pixel array is processed.

12. The method of claim 11, wherein the CMOS imager further comprises a digital processing circuit, the method further comprising:

enabling the digital processing circuit, wherein the analog pixel signal from the first portion of the pixel array is processed.

13. The method of claim 7, wherein the power sensitive application comprises video transmission via a cellular telephone.

14. The method of claim 7, wherein the power sensitive application comprises image detection and processing using a mobile device.

15. The method of claim 14, wherein the mobile device is selected from a group consisting of a cellular telephone, a personal digital assistant, and a laptop computer.

16. The method of claim 7, wherein the CMOS imager further comprises a digital processing circuit, the method further comprising:

disabling the digital processing circuit, wherein the analog pixel signal from the second portion of the pixel array is not processed.

17. The method of claim 16, wherein disabling the digital processing circuit comprises:

gating at least one clock driving the digital processing circuit.

18. The method of claim 16, wherein the digital processing circuit includes a translation unit.

19. The method of claim 7, wherein the analog processing circuit comprises:

a column amplifier; and

a level shift circuit.

20. The method of claim 18, wherein the analog processing circuit further comprises:

a black level offset;

a programmable gain amplifier; and

an ADC.

21. A method for reducing power consumption in an imaging device having an image sensor and an analog processing circuit, the method comprising:

sub-sampling the image sensor, by a sub-sample control system, wherein a first portion of the image sensor is not processed;

receiving, by a processing control system, an analog image signal from the first portion of the image sensor; and

placing, by the sub-sample control system, the analog processing circuit in a standby state when the analog image signal from the first portion of the pixel array is detected, wherein the analog image signal from the first portion is not processed.

22. The method of claim 21, wherein placing the analog processing circuit in a standby state comprises:

limiting switching of one or more inputs to the analog processing circuit.

23. The method of claim 22, wherein the analog processing circuit comprises:

a level shift circuit;

a programmable offset circuit; and

a programmable gain amplifier.

24. The method of claim 23, wherein placing the analog processing circuit in a standby state comprises:

electrically coupling one or more inputs of the analog processing circuit to a static voltage, wherein switching of the analog processing circuit is reduced.

25. The method of claim 24, wherein placing the analog processing circuit in a standby state further comprises:

maintaining switching associated with a common mode feedback loop of one or more amplifiers associated with the analog processing circuit,

wherein the one or more amplifiers are maintained in an inertial state, and a bias current associated with the amplifiers is reduced.

26. The method of claim 21, wherein sub-sampling the image sensor is done to create a bandwidth matched image output from the imaging device.

27. The method of claim 21, the method further comprising:

receiving an analog image signal from a second portion of the image sensor, wherein the second portion the image sensor is processed; and

placing the analog processing circuit in an operational mode, wherein the analog image signal from the second portion is processed.

28. The method of claim 27, wherein placing the analog processing circuit in an operational mode comprises electrically coupling one or more inputs of the analog processing circuit to the analog image signal from the second portion.

29. The method of claim 21, wherein the imaging device further comprises a digital processing circuit, the method further comprising:

disabling the digital processing circuit.