Signal processing apparatus having an analog/digital conversion function

• US 6,518,910 B2
• Filed: 02/13/2001
• Issued: 02/11/2003
• Est. Priority Date: 02/14/2000
• Status: Expired due to Term

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Yamashita, Yuichiro, Hashimoto, Seiji, Sakuragi, Takamasa
• Primary Examiner(s): WAMSLEY, PATRICK G
• Application Number:
  US09/781,165
• Publication Number:
  US 20010020909A1
• Time in Patent Office: 728 Days
• Field of Search: 341/122, 341/155, 341/162, 341/118, 341/161, 341/169, 250/300.07, 348/222, 348/227, 348/229, 348/265, 382/124
• US Class Current: 341/162
• CPC Class Codes: H03M 1/1225 using time-division multiplexing
• CPC Class Codes: H03M 1/56 Input signal compared with linear ramp
• 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 25/78 Readout circuits for addressed sensors, e.g. output amplifiers or A/D converters

Abstract

A signal processing apparatus having: a plurality of circuit blocks each circuit block including a signal source and an output transistor adapted to receive a signal generated by the signal source at a control electrode region and output a corresponding signal from a main electrode region; and an analog/digital converter circuit adapted to sequentially process the signal from each of the plurality of circuit blocks, wherein the analog/digital converter circuit includes a reference transistor for receiving a reference level at a control electrode region and outputting a corresponding signal from a main electrode region and a digital output circuit for outputting a digital signal in accordance with a signal output from the output transistor and a signal output from the reference transistor, and wherein the output transistor and reference transistor constitute an input unit of a differential amplifier circuit including the output transistor and reference transistor.

Claims

1. A signal processing apparatus comprising:

a plurality of circuit blocks, each circuit block including a signal source and an output transistor adapted to receive a signal generated by said signal source at a control electrode region and output a corresponding signal from a main electrode region; and

an analog/digital converter circuit adapted to sequentially process the signal from each of said plurality of circuit blocks,

wherein said analog/digital converter circuit comprises a reference transistor adapted to receive a reference level at a control electrode region and output a corresponding signal from a main electrode region and a digital output circuit adapted to output a digital signal,

wherein said output transistor included in the selected circuit block and the reference transistor are an input unit constituting a part of a differential amplifier circuit, and

wherein said digital output circuit outputs said digital signal in accordance with an output from said differential amplifier circuit.

2. A signal processing apparatus according to claim 1, wherein said signal source of said circuit block is a pixel including a photoelectric conversion unit.

3. A signal processing apparatus according to claim 2, wherein said pixels are arranged two-dimensionally and a plurality of said analog/digital converter circuits are arranged for sequentially processing signals from pixels of one column.

4. A signal processing apparatus according to claim 3, wherein said analog/digital converter circuit includes a counter which is controlled in accordance with a signal output from said output transistor and a signal output from said reference transistor, and the reference level is changed in accordance with a signal output from said counter.

5. A signal processing apparatus according to claim 2, further comprising:

an optical system adapted to focus light upon said pixel; and

a signal processing circuit adapted to process a signal output from said analog/digital converter circuit.

6. A signal processing apparatus according to claim 1, wherein said analog/digital converter circuit performs a comparison operation by changing, within variable range, levels of signals output from said output transistor and reference transistor, and outputs the digital signal in accordance with a comparison result, and the signal processing apparatus further comprises a control circuit for changing the variable range.

7. A signal processing apparatus according to claim 6, wherein said control circuit changes the variable range in accordance with exposure data.

8. A signal processing apparatus according to claim 6, wherein said control circuit changes the variable range in accordance with white balance data.

9. A signal processing apparatus according to claim 1, wherein said output transistor and reference transistor are field effect transistors of a same conductivity type and have approximately a same gate size.

10. A signal processing circuit comprising:

a circuit block including a signal source and an output transistor adapted to receive a signal from said signal source at a control electrode region and output a corresponding signal from a first main electrode region; and

an analog/digital converter circuit adapted to compare the signal output from the first main electrode region with a reference signal, control a level of a signal output from the first main electrode region of said output transistor in accordance with a comparison result, and output a digital signal in accordance with the comparison result.

11. A signal processing apparatus according to claim 10, wherein said analog/digital converter circuit controls a potential at a second main electrode region of said output transistor in accordance with the comparison result to thereby control the level of the signal output from the first main electrode region of said output transistor.

12. A signal processing apparatus according to claim 11, wherein the pixels are arranged two-dimensionally and a plurality of said analog/digital converter circuits are arranged for sequentially processing signals from pixels of one column.

13. A signal processing apparatus according to claim 10, wherein said signal source of said circuit block is a pixel including a photoelectric conversion unit.

14. A signal processing apparatus according to claim 13, further comprising:

an optical system adapted to focus light upon the pixel; and

a signal processing circuit adapted to process a signal output from said analog/digital converter circuit.

15. A signal processing apparatus according to claim 10, wherein said analog/digital converter circuit performs a comparison operation by changing, within a variable range, levels of signals output from said output transistor and reference transistor, and outputs the digital signal in accordance with a comparison result, and the signal processing apparatus further comprises a control circuit adapted to change the variable range.

16. A signal processing apparatus according to claim 15, wherein said control circuit changes the variable range in accordance with exposure data.

17. A signal processing apparatus according to claim 15, wherein said control circuit changes the variable range in accordance with white balance data.

18. A signal processing apparatus according to claim 10, wherein said analog/digital converter circuit includes a counter which is controlled in accordance with a signal output from said output transistor and a signal output from said reference transistor, and a level of the signal output from the first main electrode region of said output transistor is controlled in accordance with a signal output from the counter.

19. A signal processing apparatus comprising:

a plurality of pixels; and

an analog/digital converter circuit adapted to output a digital signal in accordance with a comparison result between a level of a pixel signal from each of said pixels and a comparison reference level,

wherein said analog/digital converter circuit includes a first control circuit which effects control so as to compare the level of the pixel signal with the comparison reference level while relatively changing the level of the pixel signal and the comparison level, and a second control circuit which changes a range of the relative change of the level of the pixel signal and the comparison reference level.

20. A signal processing apparatus according to claim 19, wherein said pixel includes a photoelectric conversion element and an output transistor adapted to amplify a signal from the photoelectric conversion element and output the signal as the pixel signal, the output transistor having a main electrode region for changing an output level of the pixel signal,

wherein the pixel signal level is changed by changing a control voltage applied to the main electrode region.

21. A signal processing apparatus according to claim 20, wherein the control voltage is output from the digital/analog converter circuit.

22. A signal processing apparatus according to claim 19, wherein said first control circuit changes, within the range, the comparison reference level and said second control circuit changes the range of the comparison reference level, and the comparison reference level is controlled by an output of a digital/analog converter circuit.

23. A signal processing apparatus according to claim 19, wherein the range is changed exposure data.

24. A signal processing apparatus according to claim 19, wherein the range is changed with white balance data.