Optoelectronic sensor

• US 6,452,153 B1
• Filed: 11/17/2000
• Issued: 09/17/2002
• Est. Priority Date: 11/19/1999
• Status: Expired due to Fees

• Current Assignee: CSEM Centre Suisse D'Electronique et de Microtechnique SA
• Original Assignee: CSEM Centre Suisse D'Electronique et de Microtechnique SA
• Inventors: Waeny, Martin, Lauxtermann, Stefan
• Primary Examiner(s): ALLEN, STEPHONE B
• Application Number:
  US09/716,168
• Time in Patent Office: 669 Days
• Field of Search: 250/208.1, 250/208.2, 348/294, 348/302, 348/303, 348/300, 348/301, 348/308, 348/317
• US Class Current: 250/208.1
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H04N 25/46 by combining or binning pixels
• CPC Class Codes: H04N 25/778 comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself

Abstract

The optoelectronic sensor comprises at least two pixels (1.11, 1.12, 1.21, 1.22), each pixel (1.11, 1.12, 1.21, 1.22) comprising a photodiode (2), and means for electrically connecting at least two pixels, the connecting means comprising FETs (6) for switching the connection on or off. The pixels (1.11, 1.12, 1.21, 1.22) are designed in such a way that if, e.g., four pixels (1.11, 1.12, 1.21, 1.22) are connected the photocharges generated in the connected pixels (1.11, 1.12, 1.21, 1.22) are combined in one of the connected pixels (1.22), whereby the spatial resolution of the sensor is reduced. A skimming FET (3) arranged between the photodiode (2) and a charge detection circuit (4) offers a floating source and floating drain in each pixel (1.11, 1.12, 1.21, 1.22). Thus the sensor can be manufactured in CMOS technology and is suited for photocharge binning. The invention makes it possible to vary the spatial resolution, the light sensitivity and/or the readout velocity by purely electronic means. This has the advantage of an increased light sensitivity, and, moreover, of being offset free. The power consumption of the sensor is reduced at a constant frame frequency if the spatial resolution is reduced.

Claims

1. An optoelectronic sensor comprising:

at least two pixels, each pixel comprising a diode-based photodetector for generating an electric photocharge as a function of incident electromagnetic radiation, and

means for electrically connecting said at least two pixels to each other to define at least two connected pixels,

wherein said connecting means comprises switching means for clearing and completing the electrical connection between said at least two connected pixels such that photocharges generated in said at least two connected pixels are combined in one of said at least two connected pixels, whereby a spatial resolution of the sensor is reducable.

2. The sensor according to claim 1, wherein each pixel further comprises a reset switch for resetting a sensing node of said pixel.

3. The sensor according to claim 1, wherein said switching means are designed as transistor structures and said photodetectors are, or overlap with, drain and source terminals of said transistor structures.

4. The sensor according to claim 1, further comprising means for addressing said switching means in one of two dimensions so as to form square fields with 2²ⁿ connected pixels, where n is an integer.

5. The sensor according to claim 1, further comprising means for addressing said switching means in two dimensions so as to form rectangular fields with pxq pixels, where p and q are integers.

6. The sensor according to claim 1, wherein said sensor is manufactured using a standard CMOS process.

7. The sensor according to claim 1, wherein each pixel comprises a charge detection circuit and a skimming transistor arranged between said photodetector and said charge detection circuit, said skimming transistor having a floating source and floating drain.

8. The sensor according to claim 7, wherein said skimming transistor is a field effect transistor.

9. The sensor according to claim 1, wherein said photodetectors are separated from each other by depleted channel zones of field-effect-transistor structures.

10. The sensor according to claim 9, wherein said reset switch is a field effect transistor.

11. A method for detecting electromagnetic radiation using the optoelectronic sensor according to claim 1, comprising the steps of:

generating electric photocharges as functions of incident electromagnetic radiation,

electrically connecting at least two pixels to each other to define at least two connected pixels, and

combining the photocharges generated in said at least two connected pixels in one of said at least two connected pixels, whereby the spatial resolution of the sensor is reduced.

12. The method according to claim 11, wherein a gate of a skimming transistor, which is a field-effect-transistor, is set to a DC potential, the absolute value of which is below an absolute value of a reset voltage.

13. The method according to claim 11, wherein pixels of a two-dimensional sensor are connected in one of two dimensions so as to form square fields with 2²ⁿ connected pixels, where n is an integer.

14. The method according to claim 11, wherein pixels of a two-dimensional sensor are connected in two dimensions so as to form rectangular fields with p×

q pixels, where p and q are integers.